Monosodiumoxyorganoalkoxysilanes: Synthesis and properties

Heteroatom Chemistry

Volume 17, Number 6, 2006

Monosodiumoxyorganoalkoxysilanes:

Synthesis and Properties

E. A. Rebrov and A. M. Muzafarov

Enikolopov Institute of Synthetic Polymeric Materials, Russian Academy of Sciences,

ul. Profsoyuznaya 70, Moscow 117393, Russia

Received 14 November 2005; revised 14 February 2006

INTRODUCTION

ABSTRACT: The reaction of organoalkoxysilanes

with sodium hydroxide was studied in detail. Stud-

ies indicate that this reaction involves more than one

stage and involves rather complex multistep process,

which leads to the formation of both monosodiu-

moxyorganoalkoxysilanes (MSOAS) and several sec-

ondary products. Analysis of experimental evidence

makes it possible to advance the mechanism behind

this phenomenon and to deﬁne the optimum condi-

tions for the preparation of pure MSOAS with high

yields. Different MSOAS were synthesized and their ba-

sic physicochemical properties were studied. MSOAS

are shown to constitute multifunctional reagents with

chemically independent functional groups, and their

reaction with trimethylchlorosilane selectively pro-

ceeds via ONa groups, whereas their interaction with

triethylesilanol and higher alcohols proceeds exclu-

sively via OAlk groups. Exchange interaction be-

tween MSOAS and organoalkoxysilanes via ONa

and OAlk groups was found and studied in de-

tail. Temperature corresponding to the onset of ther-

mal degradation of MSOAS was estimated to be

Monosodium salts of oxyorganoalkoxysilanols

(MSOAS) constitute new promising reagents for

the controlled synthesis of various functional

organosiloxanes with different structures. Earlier

[1,2] promising advantages of such reagents have

been vividly demonstrated for the most intricate

case such as the synthesis of organosiloxane den-

drimers. However, properties of MSOAS and pro-

cedure of their synthesis have eluded the atten-

tion of authors, and only scarce information on

this topic has occasionally appeared. This unfor-

tunate scenario had its sad consequences because

until now the above reagents have been considered

to be quite exotic, hard to get, and rather unstable

compounds.

This skeptic approach seemed to be valid and

even well justiﬁed when considering various his-

torical aspects concerning the general development

of the chemistry of alkali metal silanolates and

their use as starting reagents for the synthesis

of organosiloxanes (instead of the corresponding

silanols and siloxanols) [3–24]. Attractive features

of this approach are its relative simplicity and its

well-deﬁned mechanism of the reaction between

SiONa and SiCl groups, which leads to the for-

mation of a siloxane bond. In classical version, sim-

ilar reaction of hydroxyl-containing reagents neces-

sarily requires the involvement of third components

as acceptors of hydrogen chloride. Further-

more, as compared with the corresponding labile

silanols, sodiumoxy derivatives are known to be

rather stable compounds. Pioneering experimental

data concerning the application of less exclusive

equal to ∼180−190^◦C.

2006 Wiley Periodicals, Inc.

ꢀ

C

Heteroatom Chem 17:514–541, 2006; Published online

in Wiley InterScience (www.interscience.wiley.com). DOI

10.1002/hc.20280

Correspondence to: E. A. Rebrov; e-mail: rebrov@ispm.ru.

2006 Wiley Periodicals, Inc.

c

ꢀ

514

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 515

triorganosilanolates and organosiloxanolates con-

taining a single sodiumoxy group led to rather

encouraging results [3–5]. In addition, evident ad-

vances in this direction have triggered the devel-

opment of simple and reliable methods of the

preparation of sodiumsilanolate reagents with more

complex structures. One of the most reasonable and

widely used methods involved an interaction of bi-

functional and trifunctional organosilanes, usually

organoalkoxysilane [6–8], or diorganocyclosiloxanes

[9–12], and organosilsesquioxanes [13–20], which

were prepared by hydrolytic polycondensation of

organoalkoxysilanes with sodium hydroxide in aque-

ous alcohol solutions. However, even the ﬁrst ex-

perimental trials proved that controlled monitor-

ing over structure and composition of the formed

sodiumoxyorganosiloxanes (by varying feed ratio of

initial reagents or by changing such parameters as

type of solvent and temperature conditions) was

not feasible. Due to the speciﬁc character of chem-

ical interactions in the reaction system, this pro-

cess is totally independent of any variations in the

above parameters and entails the formation of a set

of the most stable and thermodynamically stable

sodiumsilanolates. Molecules of sodiumsilanolates

contain speciﬁed number of sodiumoxy groups and

organosiloxy fragments [12–13,15,19,20]. Further-

more, in many cases, this process leads to the forma-

tion of nonseparable mixtures of sodium-containing

homologs. It is important to note that the lower indi-

vidual representatives of this homological series are

virtually insoluble in all known aprotic organic sol-

vents. Therefore, the total replacement of hydroxyl-

containing reagents by their sodiumoxy derivatives

is baseless and unsound. Taking into account this

unfortunate historical scenario, many scientists in-

volved in the synthesis have lost their interest in such

reagents. Evidently, this is the reason why rather

scarce publications are devoted to the use of or-

ganic sodiumsilanolates for the synthesis of individ-

ual functional organosiloxanes and organopolysilox-

anes, and all results of the above works did not meet

the stated objectives [15,18,19,21,22].

methods, such as X-ray analysis, was triggered

by stored knowledge on the chemical nature of

organosilanolates and improved methods of their

synthesis. As a result, general strategy for the prepa-

ration of sodium oxyorganosilanolates has been

changed. Presently, all efforts are being focused not

on overcoming the natural barriers but also on the

development of proper favorable conditions that

assist the formation of particular sodium-containing

homologs from available compounds directly in

the course of synthesis. Evident progress in this

direction concerns the preparation of reagents with

cyclic structure; their molecules contain one ONa

group at each silicon atom, and the dimensions

of siloxane cycles may be appreciably different

[30–33]. A stereochemical aspect of this approach

also deserves a special interest: most of the synthe-

sized compounds are virtually pure cis-isomers.

It should be emphasized that the above-

mentioned classical methods were initially directed

to take full advantages offered by the functional

potential of silicon atoms in the molecules of

raw compounds, which are involved in the forma-

tion of SiONa groups and siloxane bonds in the

molecules of resultant sodiumorganosilanolates at

desired proportions. Therefore, they cannot be di-

rectly used for the synthesis of such compounds as

monosodiumoxyorganoalkoxysilanes (1) (MSOAS),

whose molecules contain a single silicon atom

with attached sodiumoxy and alkoxy fragments

(Fig. 1).

According to formal hallmarks, MSOAS belong

to a family of sodium salts of the corresponding

organosilanols. However, by their molecular design,

chemical behavior, and synthetic potential, they

may be classiﬁed as speciﬁc compounds, which are

conditionally referred to as “reagents with chemi-

cally independent functional groups.” In addition

to MSOAS, this small group of compounds in-

cludes organoalkoxysilanols (2) [34–43], organohy-

dride silanolates of alkali metals (3) [44–47], lithium

organoﬂuorosilanolates (4) [48], and lithium salts of

organophenylsilanolates (5) [49,50] (Fig. 2).

However, many publications have addressed

the synthesis of various poly(organometal-

losiloxanes) from the mixtures of the above-

mentioned reagents [13,17–19,25–29]. During the

early stages, the authors were likely to be pretty

satisﬁed with the characteristics of newly synthe-

sized compounds. Unfortunately, the problems

related to the structure and composition of initial

sodium silanolates have escaped their attention.

However, snowballing development of this chal-

lenging and promising direction of chemistry as

well as application of powerful modern physical

Organoalkoxysilanols (Fig. 2, 2) are known to be

direct structural precursors of MSOAS. In principle,

the above reagents and a well-known procedure

FIGURE 1 Monosodiumoxyorganoalkoxysilanes (MSOAS):

R: organic radicals; R¹, R²: organic radicals or alkoxy groups.

Heteroatom Chemistry DOI 10.1002/hc

516 Rebrov and Muzafarov

FIGURE 3 Composition of resulting products from the reac-

tion between tetraethoxysilane and potassium hydroxide.

FIGURE 2 Reagents with “chemically independent func-

tional groups”. Organoalkoxysilanols (2), Organohydridsi-

lanolates of alkali metals (3), Lithium organoﬂuorinesi-

lanolates (4), Lithium organophenylsilanolates (5). R¹, R²:

organic radicals.

This method of preparation of sodium and

potassium-containing

oxyorganoalkoxysilanes

seems to be rather attractive, and its advantages

over the other methods are as follows: (i) it involves

no stage of preliminary synthesis and the forma-

tion of organoalkoxysilanols; and (ii) alkali metal

hydroxide, rather than alkali metal by itself, is used

for the formation of the SiOM group. However,

analysis of this reaction (Scheme 3) leads to rather

conﬂicting results. For example, as was shown in

[54], structure and composition of the products re-

sulting from the reaction between tetraethoxysilane

and potassium hydroxide in tetrahydrofuran are

primarily controlled by the feed ratio between initial

components: Si(OEt)₄and KOH. When this ratio

is 1:1, potassiumoxytriethoxysilane (8) is formed;

when ratio is 1:2, dipotassiumoxydiethoxysilane

(9) is obtained; at 1:3, an insoluble compound of

uncertain composition is produced (Fig. 3).

Similar results were obtained when studying

the interaction of tetraethoxysilane with sodium

hydroxide [55,56]. When Si(OEt)₄:NaOH ratio

is 1:2, the reaction mixture contains unreacted

sodium hydroxide (no quantitative data are pre-

sented). Evidently, in this case, in addition to dis-

odium oxydiethoxysilane (NaO)₂Si(OEt)₂, reaction

products contain monosodium oxytriethoxysilane

NaOSi(OEt)₃.

of their synthesis [34–40] may be independently

used for the preparation of individual functional

organosiloxanes—for example, in the reactions with

SiCl groups in the presence of HCl acceptors

[35,39–41] or without any acceptors in the reac-

tions with SiNH₂groups [42,43]. Furthermore,

organoalkoxysilanols are rather mobile compounds,

which are capable of self-condensation [38,39].

Therefore, as in the above-mentioned classical case,

the best scenario involves the use of sodium salts

(such as MSOAS) for synthetic purposes.

The simplest method for the transformation

of organoalkoxysilanols into the corresponding

silanolate derivatives includes their interaction with

alkali metals (in particular, with sodium). This

procedure has been applied for the pioneering

synthesis of MSOAS, which is sodiumoxytris-(tert-

butoxysilane) (6) with bulky inert tert-butoxy groups

(Scheme 1) [51]. Its structure was conﬁrmed by

the recovery of disiloxane (7) with a yield of ∼80%

(Scheme 2).

(1)

Potassium and sodium oxytriethoxysilanes were

synthesized directly in the course of the reaction be-

tween tetraethoxysilane and sodium or potassium

hydroxides when feed ratio between (Si(OEt)₄and

MOH) is ∼2.25:1 [57–59]. The reaction products

were deliberately used as reagents for the synthe-

sis of functional aluminum silicates via their reac-

tion with AlBr₃and with aluminum diethoxy or di-

isobutylbromides. Analysis of thermal behavior of

potassium oxytriethoxysilane shows that its ther-

mal degradation commences at temperatures above

80^◦C [57]. Volatile products of thermal degrada-

tion include tetraethoxysilane (92%), ethanol (5.3%),

and ethylene (2.7%). This process is assumed

to be accompanied by the disproportionation of

potassium oxytriethoxysilane into tetraethoxysilane

and dipotassiumoxydiethoxysilane [(KO)₂Si(OEt)₂].

However, this assumption was not proved by the

analysis of solid residue after thermal degrada-

tion. It was found that the structure of degradation

(2)

However, the above methods are virtually used

to illustrate the feasibility of MSOAS synthesis,

rather than being justiﬁed as reliable procedures for

their preparation because they involve multistage

synthesis of initial organoalkoxysilanols, some of

which (especially, with methoxy and ethoxy groups)

are known to be rather unstable compounds.

In the literature, certain information concern-

ing the formation of compounds with SiOM groups

via the interaction of alkoxysilanes with sodium and

potassium hydroxides are available [26,32–38]. For-

mally, the scheme of their preparation may be pre-

sented as the reaction of nucleophilic substitution

(Scheme 3):

(3)

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 517

product appears to be far more complex and rather

uncertain.

ratio between components was equal to 2:1.

(6)

However, quite opposite results were presented

in the literature [60,61]. As was shown, sodium and

potassium hydroxides react with tetramethoxysi-

lane (under threefold excess of tetramethoxysilane)

to produce the adducts with the following com-

position: (MO)₂Si(OMe)₂·xSi(OMe)₄[60]. When the

above adducts are heated at ∼155–230^◦C in vac-

uum (20 Torr), they were decomposed into the

following components: disodium oxydimethoxysi-

lane, dipotassium oxydimethoxysilane, and tetram-

ethoxysilane. As was reported in [61], this approach

has been applied to obtain the following compounds:

(RO)₂Si(OM)₂, where R = Et, Pr, Bu; M = Na, K. Pos-

sible formation of monosodium and monopotassiu-

moxytrialkoxysilanes was not discussed.

Interesting results were reported in a brief

communication [62], but unfortunately they did

not receive any proper attention. Interaction of

dimethylcyclosilazanes with methanol solution of

potassium hydroxide was shown to produce potas-

siumoxydimethylmethoxysilane (10) (Scheme 4).

When n= 3, yield of compound 10 is equal to 88.5%;

at n= 4, the yield is 72.3%.

The formation of potassium oxydimethyl-

methoxysilane was also conﬁrmed by the prepara-

tion of the corresponding trimethylsilyl derivative

(11) (Scheme 7).

(7)

The above examples vividly demonstrate that a

systematic analysis using the literature as a data

source proves that no reliable and approved meth-

ods for the preparation of the above compounds

are available. In this connection, the objective of

this work concerns the development of straightfor-

ward and convenient method for the synthesis of

sodium salts of oxyorganoalkoxysilanes and charac-

terization of their properties.

RESULTS AND DISCUSSION

General Background

Conﬂicting literature data concerning the forma-

tion of organoalkoxysilanolates suggest that no sys-

tematic research in this direction has been con-

ducted, and the mechanism of this reaction is

still vague (Scheme 3). However, the reaction of

organoalkoxysilanes with sodium or potassium hy-

droxides for the preparation of monoderivatives

seems to be rather attractive. Without going into the

details behind this process [63], this reaction is as-

sumed to present a typical nucleophilic substitution

at the silicon atom. In this case, the hydroxyl ion

serves as the primary nucleophilic particle for at-

tacking the silicon atom. Substitution of one alkoxyl

group in the molecules of initial organoalkoxysilanes

(4)

Reaction of 1,3-dimethoxytetramethyldisiloazane

with the same reagent at 100^◦C also leads to the

formation of compound 10 with a yield of 65%

(Scheme 5).

ᮎ

by MO group, which, in turn, presents a rather

strong nucleophilic site, decreases the sensitivity of

ᮎ

the silicon atoms to the attacks from another HO

ion due to electron density redistribution and, as a

result, to the inhibition of further substitution of re-

maining alkoxyl groups by OM groups (Fig. 4).

Therefore, a thorough investigation of this re-

action and the speciﬁc features of the interaction

between the components of the reaction may al-

low one to select the conditions, which provide high

yields of pure organoalkoxysilanolates containing

(5)

It seems interesting that the resulting potassi-

umoxydimethylmethoxysilane (10) exists in the

medium, which does not contain any active

hydroxyl-containing products. This is the reason

why dimethylsilazanes were used as starting silicon-

containing components. However, as was shown,

compound 10 may be obtained with a yield of

∼86.9% directly from dimethyldimethoxysilane and

potassium hydroxide (Scheme 6). This reaction was

carried out without any solvents at 100^◦C, and feed

FIGURE 4 Electronic effects in MSOAS molecules.

Heteroatom Chemistry DOI 10.1002/hc

518 Rebrov and Muzafarov

only one OM group. In turn, the preferable route is

to synthesize monosodiumoxyorganoalkoxysilanes

from their potassium analogs. This approach may

be justiﬁed by the fact that potassium hydroxide con-

tains ∼15 wt% of water or 1 mol of water per each

1.8 mol of potassium hydroxide. One may hardly ex-

clude the possibility that this factor may exert its

negative effect on the yields and purity of potassi-

umoxyorganoalkoxysilanes and related organosilox-

anes. It is worth mentioning that sodium hydrox-

ide of the same chemical grade is free of this draw-

back. We also take into account the fact that thermal

degradation of potassiumoxytriethoxysilane com-

mences at 80^◦C [57].

polar organic solvents (n-alkanes, aromatic hydro-

carbons). Such conditions allow one to prevent any

exchange interaction between alkoxyl and chlorosi-

lyl groups (Scheme 9) and, hence, preclude the for-

mation of any by-products, which are not typical of

the main reaction (Scheme 9).

(9)

In addition to instrumental control, trimethylsi-

lylation reaction presents the simplest model for

studying the applicability of MSOAS as reagents

with “chemically independent” functional groups.

The obtained data appeared to be very helpful for se-

lecting the optimum conditions for the synthesis of

organosiloxanes with far more complex structures.

Preliminary studies showed that the reaction

of NaOH with organoalkoxysilanes is accompanied

by the formation of the corresponding alcohol

and sodium-containing products. Under certain

Interaction of Organoalkoxysilanes with

Sodium Hydroxide. Synthesis of

Monosodiumoxyorganoalkoxysilanes

Interaction between alkoxysilanes and NaOH takes

place in the presence of organic solvents or in the

presence of excessive amounts of alkoxysilane at

temperatures ranging from −30 to +100^◦C. The end

of this reaction was ﬁxed at the point of total homog-

enization of the system. In all cases, this reaction is

accompanied by an evident exothermic effect and

leads to the formation of the corresponding alcohol.

The separation of individual salt-containing

products from the reaction mixture and their analy-

sis present a rather complicated and inefﬁcient pro-

cedure. Therefore, yields and purity of ﬁnal products

were indirectly controlled by their trimethylsilyl (12)

derivatives prepared according to Scheme 8.

conditions,

monosodiumoxyorganoalkoxysilanes

(MSOAS) dominate. Along with this, analysis of

the resulting trimethylsilyl derivatives as well as

salt-free volatile liquid compounds makes it possible

to reveal several secondary concurrent processes.

It was also found that the intensity and conversion

of the above processes are controlled by external

conditions (temperature, feed ratio between starting

reagents, solvent, and duration of reaction) as well

as the molecular structure of initial organoalkoxysi-

lanes (number and type of alkoxyl groups and

organic radicals at silicon atoms).

Information listed in Table 2 shows the composi-

tion and structure of by-products, which lead to sev-

eral conclusions concerning the mechanism of their

formation. This character of by-products containing

more than one silicon atom unequivocally demon-

strates the occurrence of condensation processes in

the systems. It seems reasonable to speculate that

such processes are related to the presence of mobile

hydrogen atoms in the composition of reactive alco-

hol in the reaction volume. In this case, the primary

event giving rise to the whole cascade of secondary

processes is likely to be related to the transforma-

tion of alcohol into silanol hydroxyl according to

Schemes 10–12.

(8)

Trimethylsilyl derivatives (12) are liquids, which

may be readily isolated as individual compounds

by rectiﬁcation or trivial distillation (Table 1). Con-

stants of several compounds (12) prepared by other

methods were listed in Ref. 64.

Purity of the resulting compounds was proved

by the GLC method; this parameter was not less

than ∼99%; the structure of the above compounds

was conﬁrmed by the ¹H NMR spectroscopy and

elemental analysis. As an example, Fig. 5 presents

(10)

(11)

1

the H NMR spectra of initial dimethyldiethoxysi-

lane (I), sodiumoxydimethylethoxysilane (II), and

its trimethylsilyl derivative, 1,1,1,3,3-pentamethyl-3-

ethoxydisiloxane (III).

To avoid any additional problems and to prepare

the exact copies of sodium-containing products, re-

action (8) was carried out from −30 to −40^◦C in non-

(12)

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 519

TABLE 1 Properties of Trimethylsilyl Derivatives of MSOAS

Elemental Composition

Trimethylsilyl

Derivative

Starting

Reagent

No.

1

bp ( ^◦C)

132

n_D²⁰

Si

C

H

1.3825

2

154

177

146

175

247

230

118

134

172

151

145

1.3865

1.3867

1.4037

1.4022

1.4746

1.4721

1.3805

1.3841

1.3938

1.3891

1.3889

3

27.65

27.27

47.28

47.01

9.92

9.86

4

5

19.58

19.74

54.51

54.58

8.42

8.50

6

21.83

22.07

56.39

56.34

56.39

56.64

7

8

28.92

28.89

36.87

37.08

9.37

9.33

9

10

11

12

27.43

27.21

46.39

46.54

10.68

10.74

22.27

22.42

47.75

47.95

10.40

10.46

13

14

15

174

153

194

1.3911

1.3847

1.3896

16

17

231

245

1.3973

1.3910

25.60

26.07

39.98

39.04

8.87

8.69

Continued

Heteroatom Chemistry DOI 10.1002/hc

520 Rebrov and Muzafarov

TABLE 1 Continued

Trimethylsilyl

Elemental Composition

C H

Starting

Reagent

No.

Derivative

bp ( ^◦C)

150/10

n_D²⁰

Si

28.23

28.45

48.44

48.67

10.26

10.72

18

1.4271

19

20

135/6

168

1.4940

1.3841

31.48

31.60

40.35

40.56

9.80

9.83

Experimental and calculated values are given in nominator and denominator, respectively.

Compound numbers 4, 6, 7, 9, 12, 13, 17, 18, and 20 were synthesized for the ﬁrst time.

Initiation according to Scheme 10 should dominate

at the ﬁnal stages of the main reaction when initial

sodium hydroxide is virtually absent. In the opposite

case, at the early stages and with excessive amounts

of NaOH, processes (11) and (12) seem to be more

probable.

One may hardly exclude homocondensation be-

tween silanol intermediates (Scheme 14).

(14)

Silanol intermediates 13 and 14 may be in-

volved in further condensation reactions with initial

alkoxysilane and formed sodium oxyorganoalkoxysi-

lane, which lead to the formation of siloxane frag-

ments ( Si O Si ) and regeneration of alcohol as

exhausted at stages (10) and (11) (Scheme 13).

Due to the occurrence of thermody-

namically favorable condensation processes,

silanol intermediates are permanently gener-

ated as a result of equilibria (10) and (11).

Therefore, repeated exchange (Schemes 10–

12) and condensation (Schemes 13 and 14)

processes are likely to produce the above-mentioned

family of by-products (Table 2). Hence, timescale

factor or, namely, duration of contacts between

reaction components and alcohol should fa-

vor the accumulation of secondary by-products

(13)

TABLE 2 Qualitative Composition of Byproducts in Main Reaction

No.

Starting Reagents

Main Product

Byproducts

1

2

3

4

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 521

FIGURE 5 ¹H NMR spectra of initial dimethyldiethoxysilane (I), sodiumoxydimethylethoxysilane (II) and its trimethylsililic

derivative: 1,1,1,3,3-pentamethyl and 3-ethoxydisiloxanes (III).

in the system and would inevitably exert its

negative effect on the purity of the resulting

MSOAS.

It is also apparent that the rupture of siloxane

bonds in intermediate products under the presence

of sodium alcoholates and silanolates also affects the

ﬁnal state of the system.

The role of alcohol in the reaction volume

is reduced to the initiation of condensation pro-

cesses. Formally, this conclusion can be drawn by

Heteroatom Chemistry DOI 10.1002/hc

522 Rebrov and Muzafarov

combining, Schemes 10 (initiation) and 13 (conden-

sation). General Scheme 15 does not involve alcohol:

der study has a strong effect on the structure of by-

products containing ONa groups (97%) (except for

the reaction between trimethylmethoxysilane with

NaOH). This fact can be invoked to explain why,

in model experiments, MSOAS (Table 3, nos. 9–

11) show high reactivity toward hydroxyl-containing

reagents under rather mild conditions.

Taking into account a negative role of alcohol

formed in the course of the main reaction, it seems

interesting to conduct the synthesis of MSOAS under

the conditions of its active binding. In this con-

nection, the reaction of (N-methylamino)dimethyl-

ethoxysilane with sodium hydroxide was carried out

(Table 3, no. 12). At a feed ratio of 1:1, the yield of

sodiumoxydimethylethoxysilane was equal to ∼80%

(Scheme 17).

(15)

This reasoning also suggests an alternative alcohol-

free mechanism of secondary processes, which in-

cludes the direct condensation of alkoxyl groups

with sodium silanolate fragments according to

Scheme 16:

(16)

The data presented in the literature either directly

[65] or indirectly [66] attest to the possible occur-

rence of such reactions.

To establish the true nature of secondary pro-

cesses and to ﬁnd out the preventive measures for

suppressing the above reactions during the synthe-

sis of MSOAS, several model experiments have been

carried out; the related results are summarized in

Table 3.

(17)

The speciﬁc feature of this reaction (Scheme 17) con-

cerns the fact that the ﬁnal products do not con-

tain any compounds with hydroxyl groups. Released

gaseous methylamine containing hydrogen atoms

earlier involved in sodium hydroxide is absolutely

indifferent toward all compounds in the system. This

fact can be invoked to explain high yields and purity

of the target product (yield decreases down to 80%

as compared with theoretical level, and this behavior

is related to the fact that not all NaOH is involved

in the reaction under stoichiometric ratio between

components).

Interaction of dimethyldiethoxysilane with

NaOH under the same ratio between components

(1:1) entails the formation of a complex mixture of

resulting products, and the fraction of sodiumoxy-

dimethylethoxysilane is equal to ∼40% (Table 3,

no. 13). The above evidence vividly illustrates the

negative effect of ethanol on the systems containing

sodium oxyorganoalkoxysilanes.

Analysis of model experiments allows one

to reveal the general features behind the mech-

anism of seemingly trivial but vague reaction

of organoalkoxysilanes with sodium hydroxide

(Scheme 3), and this understanding is crucial

for solving the problems stated in this work as

well as general scientiﬁc aspects. One may ex-

pect that this reaction involves more than one

stage. To gain a deeper insight into this reaction,

it seems reasonable to consider the interaction

This evidence primarily supports the ﬁrst sce-

nario among the proposed mechanisms of secondary

processes, namely, the initiation by alcohols. Indeed,

long-term heating of homogeneous solutions of

sodium oxytriethoxysilane in perfectly dried organic

solvents (toluene and n-nonane) and under dry argon

at 100–150^◦C does not lead to any changes in the sys-

tem (Table 3, nos. 1 and 2). This result was obtained

when sodium oxydimethylethoxysilane was heated

at 100^◦C in the medium of dimethyldiethoxysilane

(Table 3, no. 3). Similar experiments were performed

in the presence of ethanol or water. As was shown,

such reactions entail the formation of the above-

mentioned products, and their content and conver-

sion of secondary processes are directly proportional

to the temperature and duration of contact between

reagents. This dependence seems to be quite rea-

sonable because, according to the advanced mecha-

nism of secondary processes, the limiting stage is the

stage of initiation. This conclusion is related to the

fact that equilibrium (19) is markedly shifted to

the left because alkoxysilanols 13 are stronger acids

than alcohols.

Due to the negative charge redistribution of

the ionic sodium silanolate group in molecules of

sodium oxyorganoalkoxysilanes onto neighboring

alkoxyl groups, sensitivity of the latter groups toward

proton attacks from hydroxyl-containing reagents

increases. This is the reason why silanol interme-

diates 13 should primarily react with the formed

sodium oxyorganoalkoxysilanes rather than with ini-

tial organoalkoxysilanes (Scheme 13). This speciﬁc

character of chemical interactions in the systems un-

between

(N-methylamino)dimethylethoxysilane

with sodium hydroxide (Scheme 17). This evidence

suggests that, at early stages of the reaction, nu-

cleophilic substitution of this ethoxyl group at

silicon atoms by hydroxyl groups in the molecules

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 523

TABLE 3 Principal Results of Model Experiments

No.

1

Scheme of Reactions. Conditions

Results of Interaction. The Main Products.

No changes in system were detected

2

3

4

No changes in system were detected

5

6

7

8

9

10

11

12

13

14

15

16

No changes in system were detected

Continued

Heteroatom Chemistry DOI 10.1002/hc

524 Rebrov and Muzafarov

TABLE 3 Continued

No.

17

Scheme of Reactions. Conditions

Results of Interaction. The Main Products.

18

19

20

21

22

23

24

25

26

27

28

29

30

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 525

of methylaminodimethylethoxysilane takes place

(Scheme 18) rather than intramolecular transfer of

OH⁻proton to a nitrogen atom in the negatively

charged pentacoordinated transition complex (15):

hydroxide presents not a single-stage but a multi-

stage process, whose ﬁrst stage involves substitution

of the ethoxyl group at a silicon atom by a hydroxyl

group (Scheme 20).

(18)

In this respect, the absence of any interaction

between bis-(dimethylamino)dimethylsilane and

sodium hydroxide even after heating for 10 h at

120^◦C is to be expected because the leaving group

(20)

As was mentioned earlier, the reaction of

alkoxysilanes with NaOH is accompanied by a

well-pronounced exothermic effect. In this con-

nection, the question concerning the driving force

of reaction (20) arises (the stage with heat re-

lease). As was shown, the thermal effect of

the interaction of sodium methylate and ethylate

with methyltrimethoxysilane and triethoxysilanes is

equal to zero. According to known literature data

[67], this interaction entails the formation of penta-

coordinated complex compound (20) (Scheme 21).

ᮎ

of dimethylamine anion (Me₂N ) is a far more

stronger nucleophilic agent than the incoming

ᮎ

hydroxyl ion (HO ) (Table 3, no. 14). At the same

ᮎ

time, reactivities of ethoxyl (EtO ) and hydroxyl

anions are virtually the same, and the reaction may

proceed according to Scheme 18.

It is also evident that the elimination of ethoxyl

anion from the transition complex (15) is the limit-

ing stage of the whole process. At later stages, the fast

interaction of the formed silanol intermediates (16)

and sodium ethylate is accompanied by the forma-

tion of rather reactive sodiumoxydimethylaminosi-

lane (17) and ethanol, which in turn quickly react

with each other, as the whole system approaches its

ﬁnal state (Scheme 19):

(21)

Taking into account the above evidence, one can con-

clude that the formation of intermediate complex 18

(Scheme 20) also proceeds without any marked ther-

mal effect. Further elimination of alkoxy group re-

ᮎ

quires a certain energy input because the EtO group

is a somewhat stronger nucleophile than the enter-

ᮎ

ing HO group. Finally, when the proposed scheme

(19)

of this process (Scheme 20) is valid, the observed

thermal effect should be controlled by the ﬁnal stage,

which involves the reaction of silanol intermediate

19 with sodium alkoxide.

Perfect separation of intermediate compounds

shown in Schemes 18 and 19 in square brackets is

conditional. It seems probable that the system virtu-

ally changes its state, and concurrent processes take

place in reaction microvolumes in the vicinity of the

nearest silicon atom.

It is necessary to mention that substitution of

ethoxyl group (ﬁrst stage) appears to be the key

event for the whole reaction because, in this case,

the negatively charged hydroxyl group is trans-

formed into the hydroxyl group of the silanol inter-

mediate (16), which shows well-pronounced acidic

properties. This process is not involved in General

Scheme 3, which is usually offered in the literature.

The above results allow one to conclude that

interaction of organoalkoxysilanes with sodium

According to general theoretical speculations,

such process is energetically favorable in most

cases because organosilanols are stronger acids than

alcohols.

Analysis of the model reaction of diphenylsilane-

diol (prototype of silanol intermediate) with sodium

t-isoamylate (Table 3, no. 15) shows that this reac-

tion is extensive even at −10^◦C and leads to an almost

quantitative formation of bisodium oxydiphenylsi-

lane. Similar results were also reported in the liter-

ature. For example, 1,3-bilithium oxytetramethyld-

isiloxane with a yield of 98% was obtained by the

reaction of tetramethyldisiloxanediol with lithium

Heteroatom Chemistry DOI 10.1002/hc

526 Rebrov and Muzafarov

t-butylate [68] (Scheme 22).

In contrast to Scheme 24, reliability of Scheme 25

is supported beyond any doubt. The most feasible

route of events taking place in this scheme is as fol-

lows (Schemes 26–28):

(22)

(26)

(27)

(28)

Therefore, the above data suggests that

Scheme 20 fairly describes the process leading to

the formation of MSOAS from organoalkoxysilanes

and sodium hydroxide.

The above analysis shows that silanol inter-

mediates 19 appear in the reaction volume even

at the early reaction stages rather than during

exchange processes. In this case, when some other

energetically favorable processes of the above

intermediates can take place, the composition of

ﬁnal products may be appreciably different. In this

respect, interaction of trimethylmethoxysilane with

NaOH (limiting case) presents a rather interesting

case (Table 3, no. 16). The main silicone-containing

product of this reaction is hexamethyldisiloxane

(95–97%); content of sodium trimethylsilanolate

does not exceed 3–5%. This reaction proceeds

rather vigorously and completes within 1.5–2 min

after mixing the reagents. One may assume that

the formation of hexamethyldisiloxane takes place

immediately after the stage of nucleophilic sub-

stitution of methoxyl by a hydroxyl group during

homocondensation of the released trimethylsilanol

or during its condensation with excessive trimethyl-

methoxysilane. In this case, sodium-containing

components serve as catalysts. Therefore, to provide

unequivocal identiﬁcation of the formed com-

pounds, sodium-containing reaction products were

treated not with trimethylchlorosilane but with

triethylchlorosilane or dimethyldichlorosilane.

Hexamethyldisiloxane is stable relative to the

components of the system under study, and its for-

mation is likely to be energetically more favorable as

compared with other possible versions. All attempts

to break down the siloxane bond in hexamethyldis-

iloxane under the action of sodium methylate, ethy-

late, and isopropylate at 100^◦C failed (Scheme 23):

The composition of the products resulting from

the reaction between trimethylalkoxysilanes with

sodium hydroxide is markedly controlled by the

nature of alkoxyl group at a silicon atom. As op-

posed to trimethylmethoxysilane, trimethylethoxysi-

lane interacts with NaOH only upon heating at 70^◦C

in the presence of pyridine. When ﬁnal products are

treated with dimethyldichlorosilane, the yield of oc-

tamethyltrisiloxane (21) is equal to 48% (Scheme

29). This fact suggests that, at the ﬁrst stage of the

reaction, sodium trimethylsilanolate with the same

or higher yield is formed.

(29)

This evidence shows that sodium trimethylsilanolate

and hexamethyldisiloxane are formed at an equal

probability due to a low activity of trimethylethoxysi-

lane in its condensation reaction with trimethylsi-

lanol.

Trimethyl isopropoxysilane and sodium hydrox-

ide do not interact with each other even after boiling

for 4 h (T ∼ 90^◦C).

Analysis of model reactions with trimethy-

lalkoxysilanes also provides valuable information

for gaining a deeper insight into the nature of

secondary processes, which accompany the forma-

tion of MSOAS. Furthermore, chemical behavior of

organosilanes containing three alkyl substituents at

the silicon atom appears to be very speciﬁc. For ex-

ample, lithium butyldimethylsilanolate is known to

interact with organomethoxysilanes (but not with

trimethylmethoxysilane) at room temperature; as a

result of this reaction, lithium methylate is obtained,

and Si O Si group is formed (Schemes 30 and

31) [65].

(23)

1

According to the H NMR spectroscopy data in

a published report [69], interaction of potassium

trimethylsilanolate with methanol can be presented

as follows:

(30)

(24)

(25)

(31)

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 527

product of this reaction (at the same feed ratio)

is monosodiumoxytriethoxysilane (86% yield). The

composition of a hypothetical adduct at x = 1 co-

incides with its composition. Therefore, analysis

solely based on the data concerning the composition

of the formed adduct leads to invalid conclusions

concerning its structure. Furthermore, monosodiu-

moxytriethoxysilane at ∼190^◦C degrades to release

tetraethoxysilane; this may be a reason behind the ill-

judged conclusion concerning the degradation of the

above-mentioned adduct. In this case, salt residue

presents a heavily condensed polymer rather than

disodium oxydiethoxysilane [(NaO)₂Si(OEt)₂], and

this reasoning is also proved in [57].

The formation of complex compound 22 dur-

ing the main reaction course is likely to play its

positive role for inhibition of the above secondary

processes. The formation of the complex compound

during the course of the main reaction assists the in-

hibition of the above secondary processes and, thus

provides a higher purity of target products. Within

this compound, delocalization of negative charge of

sodium silanolate over several centers (oxygen atoms

of alkoxyl groups) takes place. This process is nat-

urally accompanied by the decrease in the density

of negative charge and nucleophilicity of the com-

plex as compared with pure MSOAS. Thus, its sus-

ceptibility to proton attacks from reactive alcohol

and silanol intermediates is reduced. This tendency

is clearly observed during the synthesis of sodium

oxyorganoethoxysilanes when, by increasing the ra-

tio between initial reagents (ethoxysilane : NaOH)

from 1:1 to 5:1, the yield of target MSOAS markedly

increases from 40 to 95%, whereas the content of

byproducts decreases. This fact can hardly be ex-

plained by a trivial decrease in the concentrations

of interacting components in the system due to an

increased content of excessive ethoxysilanes. For

example, the reaction between dimethyldiethoxysi-

lane and NaOH (1:1) in toluene or dioxane at dilu-

tions comparable to threefold or ﬁvefold excess leads

to the formation of sodium oxydimethylethoxysi-

lane with a yield below 40%. However, the for-

mation of complex 22 during the reaction with

the excess of ethoxysilane supports the above

observations.

FIGURE 6 Pentacoordinated complex of organoalkoxysi-

lane with MSOAS.

Such reactions are not typical of the systems contain-

ing sodium oxyorganoalkoxysilanes, and this obser-

vation is proved by the results of model experiments

(Table 3, nos. 1–3). This fact also suggests that “ether

mechanism” (Scheme 32) of secondary processes in

the systems under study does not take place, at least,

at temperatures below ∼ 150^◦C. In all three above-

mentioned experiments, no diethyl ether is formed.

(32)

To complete the pattern of chemical reactions

in the system under study, it seems necessary to

consider the interaction of the formed MSOAS with

initial organoalkoxysilanes and to assess its contri-

bution to the ﬁnal result. According to the litera-

ture data [60,67], MSOAS are known to be rather

strong O⁻nucleophiles, and negative charge in

their molecules is primarily localized at the oxygen

ᮍ

ᮎ

N

atom in sodium silanolate group: Si O a; hence,

they should interact with organoalkoxysilanes and

form pentacoordinated complex compound (22)

(Fig. 6):

The formation of this complex was experi-

mentally observed for 30% solution of sodiumoxy-

dimethylethoxysilane in dimethyldiethoxysilane; its

cooling down to −45^◦C leads to the precipitation

of colorless low-melting crystals (T_m∼ −5^◦C) with

the following composition: NaOSi(Me)₂OEt·(Me)₂-

Si(OEt)₂. However, chemical stability of this

compound is low; all dimethyldiethoxysilane, in-

cluding excessive amounts, can be easily and fully

removed from the system at 25 → 40^◦C at a re-

duced pressure of 1 Torr. Taking into account

this fact, all earlier published data [60,61] seem

to be unsubstantiated. Let us mention that the in-

teraction of sodium hydroxide with threefold ex-

cess of tetraethoxysilane immediately leads to the

formation of a stable adduct with the following

composition: (NaO)₂Si(OEt)₂·xSi(OEt)₄; its separa-

tion into individual components takes place only

upon heating to 155–230^◦C at a reduced pressure of

20 Torr. The results of model experiments (Table 3,

no. 18) unequivocally demonstrate that the main

Therefore, the formation of complex 22 favors

an efﬁcient inhibition of secondary processes, and

this complex by itself is not stable to prevent the

formation of pure MSOAS.

Optimization of MSOAS Synthesis Conditions

The results of model experiments provide valu-

able information for ﬁnding optimal conditions in

Heteroatom Chemistry DOI 10.1002/hc

528 Rebrov and Muzafarov

the reactions of organoalkoxysilane with sodium

hydroxide and the preparation of pure MSOAS

with maximum yields. Initially, this procedure

has been applied for the synthesis of sodium

organoethoxysilanes as main reagents for synthetic

purposes.

for Si(OEt)₄to +30–35^◦C for PhSi(OEt)₃and

Me(Ph)Si(OEt)₂. This temperature is experimentally

estimated as the temperature at which intensive heat

release is observed in the organoethoxysilane–NaOH

system. Indeed, this method seems to be rather prim-

itive and not quite reliable for the estimation of op-

timum reaction temperature; however, its practical

value is beyond any doubt.

Interaction of Organoethoxysilanes with NaOH

Removal of reactive alcohol and excessive

organoalkoxysilane from the reaction mixture in a

1-Torr vacuum at 20–50^◦C (depending on the type of

initial organoalkoxysilane) leads to the formation of

target MSOAS with a yield of ∼96%. More detailed

information concerning optimization of this reac-

tion will be presented in the section Experimental

(Table 4).

Initial feed ratio. As was theoretically known, at least,

1 mol of organoethoxysilane is involved in complex

22 and 1 mol is spared to form target MSOAS; there-

fore, theoretical ratio between organoethoxy silane

and NaOH should be equal to 2:1. According to the

experimental data, optimal ratio is 3:1, which pro-

vides high reaction rates (reaction duration is 3–5

min) and results in a minimum duration of contacts

between MSOAS and reactive alcohol.

Interaction of Organopropoxysilanes, Isopropoxy-

silanes, and n-Butoxysilanes with NaOH. The above

data concerning the optimization of synthesis

of monosodiumoxyorganoethoxysilanes and the

Reaction temperature. Optimal (minimum) reaction

temperature depends on the structure of orga-

noethoxysilane and ranges from −30 to −25^◦C

TABLE 4 Conditions of the Reaction between Organoalkoxysilanes and Sodium Hydroxide

Trimethylsylation Reaction

Trimethylsilylic

Derivative

Main Reaction

Initial Alchoxysilane

NaOH Molar Ratio

(g/mol) of Reagents Solvent

t _mix

t _dist

Number in

Table 1

Yield

(g/%)

No.

Formula

g/mol

( ^◦C)

( ^◦C/1)

Solvent

1.1 Me₂Si(OEt)₂

1.2

14.8/0.1 4.0/0.1

29.6/0.2 4.0/0.1

1:1

2:1

Toluene

dioxane

Toluene

dioxane

25–30 20–25/20 n-Pentane

25–30 20–35/20 n-Pentane

1

7.7/40

12.5/65

1.3

1.4

44.4/0.3 4.0/0.1

74.0/0.5 4.0/0.1

53.5/0.3 4.0/0.1

89.2/0.5 4.0/0.1

62.5/0.3 4.0/0.1

3:1

5:1

3:1

5:1

3:1

5:1

1:1

3:1

1:1

3:1

–

15→25

0→25

25–40

30–45

35–50

30–40

35–45

n-Pentane

n-Hexane

n-Heptane

n-Pentane

n-Hexane

1

2

3

4

5

6

7

8

9

10

11

12

13

18.0/94

18.03/94

21.3/96

21.34/96

21.7/86

19.0/93

22.2/95

27.5/97

24.1/95

2.0/10

14.2/80

14.7/76

15.5/40

17.1/44

31.3/80

19.8/90

18.9/91

19.2/93

24.0/96

2.1 MeSi(OEt)₃

2.2

3

4

5

6

7

8.1 Me₂Si(OMe)₂

8.2

9.1 MeSi(OMe)₃

0→25

Si(OEt)₄

−15→25

Me(Vi)Si(OEt)₂48.1/0.3 4.0/0.1

20–30

ViSi(OEt)₃

PhSi(OEt)₃

57.1/0.3 4.0/0.1

72.1/0.3 4.0/0.1

Ph(Me)Si(OEt)₂63.1/0.3 4.0/0.1

5→25

30–40 80–100 Toluene

–

60.0/0.5 4.0/0.1

12.0/0.1 4.0/0.1

41.0/0.3 4.0/0.1

27.2/0.2 8.0/0.2

10→40

10→30

5→25

5→30

65–70

60–65

65–70

60–65

20–30

n-Pentane

n-Hexane

Ether

–

20–35

9.2

9.3

9.4

Ether

TGF

Dioxane

10 Me₂Si(OBu-n)₂61.3/0.3 4.0/0.1

11 Me₂Si(OPr-n)₂53.0/0.3 4.0/0.1

12 Me₂Si(OPr-i)₂

13 MeSi(OPr-i)₃

–

45–60

40–55

40–50

40–55

53.0/0.3 4.0/0.1

66.1/0.3 4.0/0.1

Items 1, 3, 2.1, 4, 5, 6, 7, 8, 9.4, 11, 12, and 13 correspond to the optimal conditions of synthesis of MSOAS.

The resulting reagents were used for the synthesis of various polyalkoxyorganosiloxanes.

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 529

interpretation of concurrent processes are also valid

for some other compounds such as sodiumoxy-

organopropoxysilanes, isopropoxysilanes, and bu-

toxysilanes. As the size of alkoxyl radical is increased

and as radicals pass from normal to iso radicals in

the molecules of organoalkoxysilanes, their activity

in the reactions with sodium hydroxide decreases.

In turn, temperature corresponding to the onset

of reaction and its duration are increased. For ex-

ample, methyltri-iso-propoxysilane starts to interact

with sodium hydroxide only at 60^◦C; dimethyldibu-

toxysilane at 65–70^◦C (for comparison, in the case

of methyltriethoxysilane, T = ∼0 to −3^◦C). However,

secondary processes tend to slow down due to a low

activity of the reaction components. The interplay

of the above factors leads to the formation of cor-

responding MSOAS with rather high yields of ∼90–

96%.

From the results of model experiments (Ta-

ble 3, no. 11), it seems expedient to ob-

tain MSOAS with bulky alkoxyl groups (from

–OC₄and higher) from the reaction of realkoxylation

of sodiumoxyorganomethoxysilanes with the corre-

sponding alcohols. This process proceeds in one

stage without any release of intermediate sodium-

oxyorganomethoxysilanes. For example, sodium

oxydimethylbutoxysilane was obtained with a yield

of ∼90% due to the interaction of (Me)₂Si(OMe)₂

with NaOH (1:1) in the medium of butanol at room

temperature. In this case, the formed methanol is

likely to be deactivated by excessive n-butanol due

to the formation of hydrogen bonds.

formed methanol, stabilization of silanol interme-

diates, and reduced concentration of reacting com-

pounds; due to high reaction rates, the fraction of

secondary by-products is reduced.

Feasibility of the Formation of Highly Substi-

tuted Disodiumoxysilanes and Trisodiumoxysilanes

During the Synthesis of MSOAS. Earlier, the for-

mation of disodiumoxyorganosiloxanes as admix-

tures containing sodiumoxy groups at different sil-

icon atoms in the course of the main reaction was

not given due importance by experts. However, as

was reported in several publications, the reaction

of organoalkoxy silanes with sodium hydroxide at

a ratio of 1:2 [54,55] and even in the presence of

excessive alkoxysilane [60,61] can entail the forma-

tion of disodiumoxy derivatives

, which

contain two sodiumoxy groups at one silicon atom.

Furthermore, some publications described the for-

mation of trisodium(potassium)oxyorganosilanes

[15,16,70]. Certain doubts concerning the reliability

of this information arise because such compounds

are not identiﬁed among all secondary products

of the main reaction. According to the proposed

mechanism of the interaction of organoalkoxysi-

lanes with sodium hydroxide (Scheme 32), the ap-

pearance of such derivatives in the reaction system

seems to be highly improbable, at least, under the

conditions providing the formation of MSOAS. In-

deed, as was expected, the electrophilicity of sili-

con atom and, hence, its susceptibility to the ac-

ᮎ

tion of nucleophilic groups such as OH should be

inevitably decreased after the substitution of one

alkoxyl group in the organoalkoxysilane molecules

Interaction of Organomethoxysilanes with NaOH.

Sodiumoxyorganomethoxysilanes occupy a promi-

nent position among various MSOAS. Excessive

amounts of organomethoxysilane in the reactions

with NaOH do not always exert their positive ef-

fect on yields and purity of the formed MSOAS.

For example, interaction of (Me)₂Si(OMe)₂with

NaOH even at a ratio of 5:1 leads to the for-

mation of a complex mixture of resulting prod-

ucts, and the content of target sodiumoxydimethyl-

methoxysilane does not exceed 10% (Table 3,

no. 19). In this case, sodiumoxymethyldimethoxysi-

lane with a yield of ∼76% is formed during the re-

action of methyltrimethoxysilane with sodium hy-

droxide at a ratio of 3:1. In contrast to other

organoalkoxysilanes, dimethyldimethoxysilanes and

methyltrimethoxy readily react with sodium hydrox-

ide in the medium of linear and cyclic ethers (diethyl

ether, teterahydrofuran, and dioxane) at a ratio of

1:1. In this case, target MSOAS are formed with a

yield of ∼80% (Table 3, nos. 21 and 22). The effect of

solvent is likely to be related to the solvation of the

ᮎ

with negatively charged ONa group. Therefore,

ᮎ

substitution of another alkoxyl group with ONa

group in MSOAS requires far more severe condi-

tions. Hence, the appearance of MSOAS in the reac-

tion volume in the course of the interaction between

alkoxysilanes and sodium hydroxide serves as a cer-

tain barrier for further exhaustive substitution of all

ᮎ

alkoxyl groups in alkoxysilane molecules ONa by

groups. The above speculations are proved by the

results of model experiments (Table 3, nos. 23–25).

The reaction of dimethyldiethoxysilane with NaOH

at a ratio of 1:2 can be completed only at tempera-

tures of 80–100^◦C, which are far from the optimum

temperature regime (15–25^◦C). Main reaction prod-

ucts are disodiumoxydimethylsiloxanes, and this fact

suggests that secondary processes dominate. The

formation of trimethylsilyl derivative corresponding

to disodiumoxydimethylsilane is not detected. Simi-

lar results were obtained for the reaction between

tetraethoxysilane and NaOH at a ratio of 1:2

or 1:3.

Heteroatom Chemistry DOI 10.1002/hc

530 Rebrov and Muzafarov

Therefore, the reaction of organoalkoxysilanes

with sodium hydroxide under optimal conditions

presents a simple and convenient way for the syn-

thesis of MSOAS.

ethoxysiloxane and three silicon atoms. As was ex-

pected, this reaction entails the formation of ethanol

and dimethyldiethoxysilane, which presents the

central structural fragment of the initial compound.

In the case of trimethylsilylation, the following

compounds are identiﬁed: tetraethoxysilane and

1,1,1,-trimethyl,3,3,3-triethoxydisiloxane, which is

trimethylsilyl derivative of sodiumoxytriethoxysi-

lane (Table 1, no. 3); most of the ﬁnal products

are involved in the residue, which presents the

mixture of nondistillable compounds. This evidence

looks rather convincing and does not require

any additional comments. In a simpler version,

interaction of 1-methoxypentamethyldisiloxane

with sodium hydroxide (Table 3, no. 30) leads

to the formation of the target compound as 1-

sodiumoxypentamethyldisiloxane with a yield of

∼73%, in addition to sodium trimethylsilanolate

(∼7%) and virtually equal amounts (10%) of 1,3-

disodiumoxytetramethyldisiloxane and its homolog,

1,5-disodiumoxyhexamethyltrisiloxane. Despite the

evident progress shown by the latest results, it

is too early to use this mixture for synthetic

purposes.

Interaction of Sodium Hydroxide with

Organoalkoxysiloxanes. Prospects of Synthesis

of Sodiumoxyorganoalkoxysiloxanes

In contrast to organoalkoxysilanes, interaction

of organoalkoxysiloxanes with sodium hydroxide

is unfortunately inapplicable for the introduc-

tion of sodiumsilanolate groups into organosiloxane

molecules. Even under the above-mentioned optimal

conditions, this reaction is usually accompanied by

the degradation of siloxane groups, which proceeds

along with the exchange reactions between alkoxyl

and sodiumoxy groups. As a result, a complex mix-

ture of various compounds is formed, and their sepa-

ration into individual components appears to be im-

possible. Furthermore, in most cases, ﬁnal products

do not contain any target components. For example,

interaction of 1,3-diethoxytetramethyldisiloxane

with sodium hydroxide (Table 3, no. 29) and si-

multaneous azeotropic distillation of the formed

ethanol with toluene ﬁnally leads to the forma-

tion of 1,5-disodiumoxyhexamethyltrisiloxane,

Properties of

Monosodiumoxyorganoalkoxysilanes

instead

of

the

expected

1-sodiumoxy,3-

this re-

ethoxytetramethyldisiloxane.

When

Physical Properties. As was shown in our

studies, interaction of organoalkoxysilanes with

sodium hydroxide allows one to synthesize vari-

ous MSOAS as well as change the chemical na-

ture of their organic decoration and vary the num-

ber of alkoxyl groups at silicon atom (from one

to three) (Fig. 7). Usually, direct yields of MSOAS

are high at 93–97%. The only exception concerns

sodiumoxytriethoxysilane, and its yield does not

action is carried out under mild conditions,

trimethylsilyl derivative of target product as 1-

ethoxyheptamethyltrisiloxane (Table 1, no. 20)

is obtained, and its yield is equal to ∼9.7%.

In

a somewhat complex case, interaction of

3,3-dimethylhexaethoxytrisiloxane with sodium

hydroxide does not lead to the formation of any

sodiumoxy derivatives, which contain both initial

FIGURE 7 A family of synthesized MSOAS.

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 531

Interaction of MSOAS with organochlorosilanes. Be-

exceed 86%. However, this yield can be in-

creased up to 93% by using the exchange

reaction between tetraethoxysilane and sodiumoxy-

dimethylethoxysilane (Table 3, no. 17), a challeng-

ing problem that will be discussed in more detail

later.

With the exception of methoxyl derivatives, a

combination of ionic sodiumoxy and organic alkoxyl

groups in the molecules of most MSOAS is an attrac-

tive solution because the above compounds can be

dissolved well in both polar and nonpolar organic

solvents.

cause of the presence of an ionic ONa group,

ᮎ

MSOAS are rather strong

O nucleophiles, which

are able to enter the S_N2 substitution reactions with

organosilicon compounds that contain easily re-

moved groups (for example, Hal⁻or acyloxy anions)

at silicon atoms (Scheme 33):

(33)

If MSOAS are well dissolved in such nonpo-

lar solvents such as n-alkanes and aromatic hydro-

carbons, the formed secondary products (primarily,

disodiumoxyorganosiloxanes) appear to be virtually

insoluble. This fact makes it possible to obtain pure

MSOAS by using rather simple techniques such as

ﬁltration or decantation of their solutions.

By their appearance, MSOAS present crystalline

compounds, and their melts are rather susceptible to

supercooling (except for sodiumoxytriethoxysilane,

which is infusible).

All MSOAS are known to be thermally sta-

ble compounds among various sodiumoxyorganosi-

lanes and siloxanes. For example, thermal degrada-

tion of sodiumoxydimethylethoxysilane in its melt

(T_m∼ 70^◦C) or in its n-undecane solution takes

place at 185–190^◦C. Among volatile liquid prod-

ucts of thermal degradation, trimethylethoxysi-

lane (∼95%) and dimethyldiethoxysilane are iden-

tiﬁed. Solid salt products are presented by

disodiumoxydimethylsilane, sodium ethylate, and

sodium trimethylsilanolate (in total, ∼25%; other

75% involve the mixture of oligomer polysodiu-

moxymethylethoxysiloxanes). Analysis of the ther-

mal degradation products primarily suggests that,

at intermediate stages, redistribution of methyl (not

ethoxyl groups) takes place. This is in contrast

to the exchange interaction between MSOAS and

organoalkoxysilanes. Thermal degradation of sodi-

umoxytriethoxysilane commences within the same

temperature interval; however, this process proceeds

with slower rates. In this case, the only volatile

product of thermal degradation is tetraethoxysilane.

The salt fraction is presented by three-dimensional

polysodiumoxyethoxysiloxane.

Within the scope of this work, we studied the in-

teraction of MSOAS with trimethylchlorosilane in

detail (Scheme 8). This reaction readily proceeds

in the medium of nonpolar organic solvents solely

through sodiumoxy groups when alkoxyl reactive

sites remain intact. This process leads to the forma-

tion of the corresponding trimethylsilyl derivatives

(Table 1) with almost quantitative yields.

Interaction of MSOAS with hydroxyl-containing

reagents. Due to the partial redistribution of

negative charge of the ionic sodiumsilanolate

group in MSOAS molecules over oxygen atoms

of neighboring alkoxyl groups, their reactivity to-

ward compounds with mobile hydrogen atoms

(for example, hydroxyl-containing reagents) in-

creases. This property was discussed earlier

when analyzing the speciﬁc features of sec-

ondary processes taking place during synthe-

sis. As was shown in model experiments (Ta-

ble 3, no. 10), sodiumoxymethyldimethoxysilanes

and diethoxysilanes readily react with triethylsi-

lanol even at room temperature, and this reaction

is accompanied by a moderate exothermic effect

(Scheme 34):

(34)

When the reaction products are treated with

trimethylchlorosilane, compound 24 (Scheme 35) is

obtained, and its yield is equal to 24–55%.

Chemical Properties. Chemical behavior of

MSOAS is primarily controlled by their molecular

structure. Depending on the conditions and type of

reagents, they selectively react either with ONa or

OR groups. According to this criterion, MSOAS can

be classiﬁed as reagents with “chemically indepen-

dent functional groups.”

(35)

Reactions of realkoxylation of sodiumoxy-

dimethylmethoxysilane with n-butanol or isoamyl

Heteroatom Chemistry DOI 10.1002/hc

532 Rebrov and Muzafarov

alcohol (Table 3, no. 11) proceed virtually quanti-

tatively with the formation of sodiumoxydimethyl-n-

butoxysilanes and isoamyloxysilanes. This approach

offers the best scenario for their preparation

(Scheme 36):

(36)

(38)

The preferential formation of stable compound

29 corresponds to the earlier results obtained for

the decomposition reaction of dimethylcyclosilox-

anes with sodium hydroxide [12].

Replacement of monoatomic alcohols from C₄

and higher with its diatomic analogs leads to

the formation of more complex mixture of ﬁ-

nal products. Obviously, it is caused by process-

ing reiterated intermolecular realkoxylation pro-

cesses in the reactive system. As a result of the

interaction of sodiumoxymethyldimethoxysilane

with 1,4-butandiol, only the cyclic product of in-

tramolecular condensation (25) was successfully

identiﬁed (Scheme 37). Its trimethylsilyl derivative

(26) was isolated with the yield ∼22%. The main

part of obtained products ∼64% was undistillable

substances (1 Torr).

Exchange

Interaction

of

MSOAS

with

Organoalkoxysilanes. Interaction

of

MSOAS

with organoalkoxysilanes leads to the formation

of pentacoordinated complex compound 22. More

detailed studies show that, under certain condi-

tions, complex 22 experiences internal migration

of alkoxyl groups from one silicon atom to an-

other, and this migration is likely to proceed via a

four-centered transition state (Fig. 8).

Exchange interaction within the transition com-

plex 30 can be presented in a simpler way as the case

of limiting separation of components (Scheme 39):

(39)

(37)

When R¹= R³and R²= R⁴, no visible changes in the

However, the preparation of realkoxylation

products with acceptable yields presents a challeng-

ing task. For example, interaction of sodiumoxy-

dimethylmethoxysilane with isopropanol leads to

the formation of a complex mixture of compounds,

among which the above-mentioned secondary prod-

ucts are predominant (Table 1, no. 3). Positive results

of earlier experiments are related to low activity of

n-butanol and isoamyl alcohol in the above exchange

and condensation processes.

system take place (Table 3, nos. 2 and 3). Inversely,

With the internal generation of silanol inter-

mediates (dimethylethoxysilanol 27) in the medium

of sodiumoxydimethylethoxysilane by acetic acid at

−50^◦C and the further increase to room tempera-

ture, primary products of reaction 28 are not identi-

ﬁed. Exchange and condensation processes proceed

rather intensively and ﬁnally lead to the formation

of 1,5-disodiumoxyhexamethyltrisiloxane 29 with a

yield of ∼90% (Scheme 38).

FIGURE 8 Internal interactions of organoalkoxysilane with

MSOAS in complex.

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 533

removal of lower boiling alkoxysilane from the re-

action volume can fully shift the equilibrium of re-

action (38) to a desirable direction. For example,

heating of homogeneous solution of NaOSi(Me)₂OEt

(33%) in the medium of Si(OEt)₄at 70^◦C and at

100 Torr entails an almost complete isolation of

(Me)₂Si(OEt)₂(Table 3, no. 17). In this case, sodi-

umoxytriethoxysilane (NaOSi(OEt)₃) is formed with

a yield of 93%. Purity of this ﬁnal product is rather

high, and this level of purity cannot be attained when

this compound is obtained directly from Si(OEt)₄

and NaOH (Table 3, no. 18).

Therefore, the exchange reaction (Scheme 39)

offers wide possibilities for the synthesis of vari-

ous (including MSOAS) organosilicon sodiumoxy

derivatives under aprotonic conditions. For exam-

ple, depending on the type of solvent, feed ratio

of starting reagents, temperature, and duration of

this process, interaction of 1,2-bis-(diethoxymethyl-

silyl)ethane with sodiumoxydimethylethoxysilane

allows a stepwise substitution of ethoxyl groups by

sodiumsilanolate groups depending on synthetic

requirements (Scheme 40):

(a) This reaction presents a rather complex pro-

cess, which proceeds in more than one

stage. Speciﬁc character of chemical inter-

actions in the reaction systems leads to

the formation of various reaction products,

which primarily involve target compounds

based on monosodiumoxyorganoalkoxysi-

lanes. Electronic effects in the molecules

of such compounds prevent further exhaus-

tive substitution of alkoxyl groups in their

composition by sodiumsilanolate groups.

The mechanism for their formation is

proposed.

(b) Composition and structure of secondary re-

actions or by-products are studied. The most

probable reason behind their formation is

shown to be related to the presence of alcohol

formed in the course of main reaction.

(c) This study allows us to propose a simple

and convenient method for the preparation

of pure MSOAS. Various target compounds

were synthesized, and their basic physic-

ochemical properties were studied. As is

shown, MSOAS are reagents with chemically

independent functional groups such as NaO

and OEt.

2. The exchange interaction between MSOAS and

organoalkoxysilanes is revealed and studied in de-

tail. This process can be used for the synthesis of

MSOAS and other organosilicon compounds con-

taining sodiumoxy group.

(40)

Unfortunately, this convenient reaction can hardly

be used for the incorporation of sodiumsilanolate

groups into organosiloxane molecules because of

the concurrent degradation processes, which are

accompanied by the rupture of siloxane bond. As a

result, a complex mixture of ﬁnal products is formed

(Table 3, no. 28).

Similar exchange reactions (39) but only com-

bined with sodiumoxyorganoalkoxysilanes (Scheme

41) are virtually prohibited:

3. The reaction of MSOAS with trimethylchlorosi-

lane is studied in detail. This reaction proceeds

only via sodiumoxy groups. Important informa-

tion concerning the use of MSOAS for the synthe-

sis of functional organosiloxanes of more com-

plex structure is obtained.

EXPERIMENTAL

1. Initial Compounds. Method of Investigation

Initial compounds such as organochlorosilanes,

alcohols, and organic solvents were pretreated

according to the adopted procedures [71]. Organo-

alkoxysilanes, organoaminosilanes, organoalkoxy-

(41)

Such processes can take place only at high temper-

atures of about 180–200^◦C when the degradation of

MSOAS occurs.

aminosilanes,

organoalkoxysiloxanes,

organo-

silanols, and organocyclosiloxanes were synthesized

using the procedures described in [72].

GLC analysis was performed on an LChM-80

chromatograph; length of columns was equal to

1 or 2 m; their internal diameter was equal to

3 mm; catharometer—detector; carrier gas—helium

CONCLUSIONS

1. The reaction of organoalkoxysilanes with sodium

hydroxide is studied.

Heteroatom Chemistry DOI 10.1002/hc

534 Rebrov and Muzafarov

(30 mL/min), immobile phase: SE-30 deposited onto

a Chromatron-N-AW-HMDS (5% SE-30).

dimethylethoxysilane (28.5 g, 0.2 mol) was dissolved

at room temperature in tetraethoxysilane (125.0 g,

0.6 mol). The stirred solution was heated to 70^◦C

at a reduced pressure of 100 Torr. The formed

dimethyldiethoxysilane was slowly removed from

the system through long fractional distillation col-

umn. After the extraction of dimethyldiethoxysilane,

the mixture was stirred under the same conditions

for 3 h. Excessive tetraethoxysilane was evaporated

at a reduced pressure of 1 Torr at 35–50^◦C. Solid

residue was dissolved in dry n-heptane (150 mL)

and treated with a solution of trimethylchlorosilane

(24.0 g, 0.22 mol) in n-heptane (40 mL) according to

procedure 2.1. As a result, we obtained 46.8 g (93%

yield) of 1,1,1,-trimethyl,3,3,3-triethoxydisiloxane

(Table 1, no. 3).

Proton nuclear magnetic resonance (¹H NMR)

spectra were recorded on a Bruker WP-200 and WP-

250 spectrometers in CDCl₃, CCl₄, and C₆D₆. Internal

reference sample: tetramethylsilane (TMS), CHCl₃.

2. Reaction of Organoalkoxysilanes with

Sodium Hydroxide. Synthesis of

Monosodiumoxyorganoalkoxysilanes

2.1. General Procedure of Trimethylsilylation

of Organosodiumsilanolates. 50% solution of

trimethylchlorosilane (in 5–10% excess per sodium

oxy groups with respect to stoichiometry) was

added in drops to a stirred homogeneous solution or

suspension of organosodiumsilanolates in nonpolar

organic solvent (n-alkanes, aromatic hydrocarbons)

at −40 to −30^◦C in the ﬂow of dry argon. Reaction

mixture was stirred for 1 h at 25^◦C and for 0.5 h at

35–60^◦C. Sodium chloride precipitate was ﬁltered

and washed three times with solvent; ﬁltrate was

evaporated to remove solvent; residue was separated

by a simple distillation or rectiﬁcation. Purity of

the prepared products was controlled by the GLC

method, and their structure was conﬁrmed by the

¹H NMR spectroscopy. For known compounds,

their constants were compared with the literature

data [64]. Yields of trimethylsilyl derivatives for

each case under study are listed below.

2.4. Thermostating of Sodiumoxytriethoxysilane

Solutions Under Different Conditions

2.4.1. Solution of sodiumoxytriethoxysilane (24.3 g,

0.12 mol) in dry toluene (100 mL) was heated in

the ﬂow of dry argon at 100–110^◦C for 8 h. No vis-

ible changes in the systems were detected. Toluene

was evaporated from the solution at a reduced pres-

sure of 20 Torr; residue was dissolved in n-hexane

and treated with trimethylchlorosilane (14.5 g, 0,13

mol) in n-hexane (30 mL). As a result, we ob-

tained 29.1 g (96% yield) of 1,1,1,-trimethyl, 3,3,3-

triethoxydisiloxane (Table1, no. 3).

2.4.2. Solution of sodiumoxytriethoxysilane (28.3 g,

0.14 mol) in dry n-nonane (120 mL) was stirred un-

der the ﬂow of dry argon at 150^◦C for 12 h. No visi-

ble changes in the systems were detected. n-Nonane

was evaporated from the solution at a reduced pres-

sure of 1 Torr; the residue was dissolved in n-hexane

and treated with trimethylchlorosilane (17.0 g, 0.16

moles) in n-hexane (35 mL). As a result, we ob-

tained 33.8 g (96% yield) of 1,1,1,-trimethyl,3,3,3-

triethoxydisiloxane (Table 1, no. 3).

2.2. General Procedure of the Reaction Between

Organoalkoxysilanes and Sodium Hydroxide. Synthe-

sis of Monosodiumoxyorganoalkoxysilanes. A solid

sodium hydroxide at temperature T_mixwas added to

organoalkoxysilane or its solution in organic solvent.

Suspension was mixed in the ﬂow of dry argon to

achieve a complete homogenization of the system.

Highly volatile liquid components (organic solvent,

excessive organoalkoxysilane, and reactive alcohol)

were removed in vacuum (1 Torr) at temperature

T_dist. Residue was dissolved or suspended in organic

solvent; then, it was subjected to trimethylsilylation

according to procedure as described in procedure

2.1. Speciﬁc conditions of this reaction and yield

of target compounds are listed in Table 4. Yields of

trimethylsilyl derivatives of MSOAS were calculated

from the data of GLC analysis, which allowed one to

estimate their true amounts among other reaction

products.

2.4.3. Solution of sodiumoxytriethoxysilane (36.4

g, 0.18 mol) in n-heptane (180 mL) containing 5

wt% of ethanol was stirred at 40–50^◦C for 9 h. This

process led to the precipitation of a white solid.

n-Heptane was evaporated at a reduced pressure of

20 Torr. To the solid residue was added dry toluene

(100 mL), which was also evaporated at 20 Torr.

This procedure was repeated three times in order to

remove the traces of ethanol. The residue was sus-

pended in n-hexane (120 mL) and treated with the

solution of trimethylchlorosilane (21.7 g, 0.20 mol)

in of n-hexane (55 mL). As a result, we obtained

2.3. Exchange Reaction Between Sodiu-

moxydimethylethoxysilane and Tetraethoxysilane.

Synthesis of Sodiumoxytriethoxysilane. After its

recrystallization from n-hexane, sodiumoxy-

21.6

g

(47.5% yield) of 1,1,1,-trimethyl,3,3,3-

(42.3% yield)

triethoxydisiloxane and 16.4

g

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 535

of

3,3,5,5-tetraethoxyhexamethyltetrasiloxane,

containing 5 wt% of ethanol was stirred at 90–

95^◦C for 14 h. In this case, the precipitation of a

voluminous white solid was observed. All further

steps were similar to those described in procedure

2.4.3. As a result, we obtained 5.8 g (15.0% yield)

of pentamethylethoxydisiloxane, 9.3 g (30.0% yield)

of decamethyltetrasiloxane (Table 1, no. 15), 12.8 g

(50.0% yield) dodecamethylpentasiloxane (Table 1,

no. 16).

(Table 1, no. 17). Found: n²_D⁵= 1.3910, d₄²⁵= 0.9548,

M_D^R= 108.58, T_b= 245^◦C; Si 25.60, C 39.98, H 8.87.

Weight of distillation fractions: 0.8 g (2% with

respect to the total amount of isolated products).

Calcd: M_D^R= 107.19; Si 26.07, C 39.04, H 8.89. H

1

NMR (CDCl₃, 250 MHz): δ = 0.050 (s, 18H), δ = 1.180

(t, 12H), δ = 3.680 (q, 8H).

2.4.4. Solution of sodiumoxytriethoxysilane (36.4 g,

0.18 mol) in n-heptane (180 mL) containing 5 wt%

of ethanol was stirred at 65^◦C for 14 h. In this case,

the precipitation of a voluminous white solid was

observed. All further steps were similar to those de-

scribed in procedure 2.4.3. As a result, we obtained

2.6. Interaction of Sodiumoxydimethylethoxy-

silane with Water. A solution of water (1.8 g, 0.10

mol) in dioxane (15 mL) was added to a solution of

sodiumoxydimethylethoxysilane (28.5 g, 0.20 mol)

in toluene (130 mL) under stirring at 25^◦C. Tem-

perature in the system was spontaneously increased

to 35^◦C; the solution became brightly crimson and

fully homogeneous. The mixture was stirred at 60^◦C

for 2 h; then, the formed ethanol was removed by

azeotropic distillation with toluene. In this case, the

precipitation of a white solid based on reaction prod-

ucts was observed. The residue was ﬁltered, washed

with dry toluene, dried at a reduced pressure of 1

Torr at 50^◦C, suspended in dry n-hexane (60 mL),

and treated with a solution of trimethylchlorosilane

(24.0 g, 0.22 mol) in n-hexane (55 mL). As a re-

sult, we obtained 19.0 g (60% yield) of decamethyl-

tetrasiloxane (Table 1, no. 15), 5.1 g (20% yield) of

dodecamethylpentasiloxane (Table 1, no. 16).

17.3

g (38.1% yield) of 1,1,1,-trimethyl,3,3,3-

triethoxydisiloxane, 15.8 g (40.7% yield) of 3,3,5,5-

tetraethoxyhexamethyltetrasiloxane. Weight of

distillation fractions: 3.4 g (9.3% with respect to the

total amount of isolated products).

2.4.5. Solution of sodiumoxytriethoxysilane (36.4 g,

0.18 mol) in toluene (180 mL) containing 0.1 wt%

of water was stirred and heated at 80 to 95^◦C for

2.5 h. In this case, the precipitation of a voluminous

white solid was observed. All further steps were simi-

lar to those described in procedure 2.4.3. As a result,

we obtained 3.4 g (7.6% yield) of 1,1,1,-trimethyl,

3,3,3-triethoxydisiloxane, 1.1 g (2.8% yield) 3,3,5,5-

tetraethoxyhexamethyltetrasiloxane, 8.8 g of mix-

ture of oligomer products: T_b= 163–200^◦C. Weight

of distillation fractions: 17.3 g (56.5% with respect

2.7. Interaction of Sodiumoxydimethylethoxy-

silane with Acetic Acid. Acetic acid (6.0 g, 0.10 mol)

was added in drops to a solution of sodiumoxy-

dimethylethoxysilane (28.5 g, 0.20 mol) in toluene

(130 mL) under stirring at –50^◦C. The mixture was

stirred at –30^◦C for 2 h; then, the temperature was

increased to room temperature. Residue of sodium

acetate was ﬁltered and washed with toluene. Re-

action ethanol was removed from the system by

the azeotropic distillation with toluene. In this case,

the precipitation of a white solid based on reaction

products was observed. The precipitate was ﬁltered,

dried at 50^◦C at a reduced pressure of 1 Torr,

and treated with a solution of trimethylchlorosi-

lane (24.0 g, 0.22 mol) in n-hexane (55 mL). As

a result, we obtained 0.5 g (1.6% yield) of de-

camethyltetrasiloxane and 15.4 g (60 % yield) of

dodecamethylpentasiloxane.

1

to the total amount of isolated products). H NMR:

Found: ratio of integral intensities of signals from

protons of methyl radicals at silicon atoms H_Si(CH

)

3

δ = 0.05 (s) and ethoxyl groups H_SiOCH

δ = 1.18 (t),

CH

2

3

H_SiOCH

δ = 3.68 (q) was equal to 1.65:1. Calcd: for

CH

3

2

repeat unit Si(OC₂H₅)OSi(CH₃)₃, 1.80:1.

2.5. Thermostating of Sodiumoxydimethyl-

ethoxysilane Solutions Under Different Conditions

2.5.1. A homogeneous solution of sodiumoxydi-

methylethoxysilane (28.5 g, 0.20 mol) recrystallized

from n-hexane was stirred in dimethyldiethoxysi-

lane (148.0 g, 1.0 mol) at 100^◦C for 6 h. No visible

changes in the systems were detected. To remove

dimethyldiethoxysilane, the solution was evaporated

at 25–35^◦C and at a reduced pressure of 1 Torr; solid

residue was dissolved in dry n-hexane (85 mL) and

treated with the solution of trimethylchlorosilane

(24.0 g, 0.22 mol) in n-hexane (55 mL). As a result, we

obtained 36.0 g (94% yield) of pentamethylethoxy-

disiloxane (Table 1, no. 1).

2.8. Interaction of MSOAS with Alcohols

2.8.1. Interaction of sodiumoxydimethylmethoxy-

silane with n-butanol. Synthesis of sodiumoxydi-

methyl-n-butoxysilane. Sodium hydroxide (4.0

2.5.2. Solution of sodiumoxydimethylethoxysilane

(28.5 g, 0.20 moles) in n-heptane (120 mL)

g, 0.10 mol) was added to

a

solution of

Heteroatom Chemistry DOI 10.1002/hc

536 Rebrov and Muzafarov

dimethyldimethoxysilane (12.0 g, 0.10 mol) in n-

butanol (26.0 g, 0.35 mol), under stirring at 20^◦C. The

mixture was stirred until its complete homogeniza-

tion was achieved; then, excessive n-butanol and

formed methanol were removed at a reduced

pressure of 1 Torr at 80^◦C. Residual n-butanol was

removed by azeotropic distillation with toluene at a

reduced pressure of 20 Torr. The resulting product

was colorless viscous liquid, which was dissolved in

dry n-hexane (45 mL) and treated with a solution of

trimethylchlorosilane (12.0 g, 0.11 mol) in n-hexane

(40 mL). As a result, we obtained 19.8 g (90%

yield) of n-butoxypentamethyldisiloxane (Table 1,

no. 10).

2.9. Interaction of Dimethyldimethoxysilane

with Sodium Hydroxide in n-propanol. According to

procedure 2.8, 12.0 g (0.10 mol) of dimethyldimeth-

oxysilane, 4.0 g (0.10 mol) of sodium hydroxide,

21.0 g (0.35 mol) of n-propanol, and 12.6 g (0.12

mol) of trimethylchlorosilane yield 2.0 g (10%) of

n-propoxypentamethyldisiloxane (Table 1, no. 11).

2.10. Interaction of MSOAS with Triethylsi-

lanol

2.10.1. Interaction of sodiumoxydimethylethoxy-

silane with triethylsilanol. A solution of triethysilanol

(12.2 g, 0.092 mol) in ether (16 mL) was added in

drops to a solution of sodiumoxydimethylethoxysi-

lane (7.9 g, 0.045 mol) in dry diethyl ether (20 mL),

under stirring at 10^◦C. Temperature in the reac-

tion system was spontaneously increased to 25^◦C.

The mixture was stirred at 25^◦C for 1 h and al-

lowed to stay at a reduced pressure of 20 Torr

and then at 1 Torr and at 35–40^◦C until con-

stant weight was attained (15.2 g). The resulting

residue was a colorless viscous liquid, which was

dissolved in dry n-hexane (45 mL) and treated

with a solution of trimethylchlorosilane (5.6 g,

0.052 mol) in n-hexane (20 mL). As a result,

we obtained 10.01 g (53.3% yield) of 3-methyl,3-

(trimethylsiloxy)hexaethyltrisiloxane (Table 1, no.

18). Found: T_b= 150–151^◦C/10 Torr, n_D²⁵= 1.4271; Si

28.23, C 48.44, H 10.76. Calcd: Si 28.45, C 48.67,

H 10.72. ¹H NMR (CCl₄, 200 MHz): δ = 0.275 (s,

3H), δ = 0.353 (s, 9H), δ = 0.823 (q, 4H), δ = 1.212

(t, 6H).

2.8.2. Interaction of sodiumoxydimethylmethoxysi-

lane with isoamyl alcohol. Synthesis of sodiu-

moxydimethylisoamyloxysilane. Sodium hydroxide

(5.4 g, 0.135 mol) was added to a solution of

dimethyldimethoxysilane (21.0 g, 0.175 mol) in

isoamyl alcohol (41.67 g, 0.472 mol) under stirring at

20^◦C. Temperature in the system was spontaneously

increased to 40^◦C. The mixture was stirred until its

complete homogenization was achieved; then, the

excess isoamyl alcohol and formed methanol were

removed at a reduced pressure of 1 Torr at 85^◦C.

Residual isoamyl alcohol was removed by azeotropic

distillation with toluene at a reduced pressure of 20

Torr. The resulting product was a colorless viscous

liquid, which was dissolved in dry n-hexane (65 mL)

and treated with a solution of trimethylchlorosilane

(15.3 g, 0.141 mol) in n-hexane (40 mL). As a result,

29.4 g (93% yield) of isoamyloxypentamethyldisilox-

ane was obtained (Table 1, no. 10).

2.10.2. Interaction of sodiumoxydimethylmethoxy-

silane with triethylsilanol. A solution of triethylsi-

lanol (11.0 g, 0.083 mol) in ether (15 mL) was added

in drops to a suspension of sodiumoxydimethyl-

methoxysilane (6.0 g, 0.042 mol) in dry diethyl

ether (20 mL) under stirring at 10^◦C. The solution

was stirred until its complete homogenization was

achieved. All further steps were similar to those de-

scribed in procedure 2.10.1. As a result of treat-

ment with a solution of trimethylchlorosilane (5.8 g,

0.053 moles) in n-hexane (20 mL), 3.94 g (24% yield)

of 3-methyl,3-(trimethylsiloxy)hexaethyltrisiloxane

was obtained.

2.8.3. Interaction of sodiumoxymethyldimethoxy-

silane with 1,4- butanediol. Solution of 20.98 g (0.154

mol) methyltrimethoxysilane in dioxane (15 mL)

was added to a suspension of 5.60 g (0.140 mol)

sodium hydroxide in dioxane (15 mL) under stirring

at 15^◦C. The mixture was stirred for 0.5 h until its

complete homogenization was achieved. To the re-

sulting solution, the solution of 12.62 g (0.140 mol)

1,4- butanediol in dioxane (15 mL) was added under

stirring at 10^◦C. The mixture was stirred for 1 h at

20^◦C; then, dioxane and formed methanol were re-

moved at a reduced pressure of 1 Torr at 40–50^◦C.

The suspension of insoluble residue was treated

with a solution of trimethylchlorosilane (16.3 g,

0.150 mol) in n-hexane (40 mL) at –30^◦C. The mix-

ture was stirred at 25^◦C for 1 h and at 60^◦C for 0.5 h.

As a result, 6.69 g (22%) 1-methyl, 1-trimethylsiloxy-

1-sila-2,7 dioxacycloheptane and 19.4 g of undistill-

able products were obtained. Found: T_b= 63–65^◦C/2

2.11. Interaction of Diphenylsilanediol with

Sodium Tert-Isoamylate

2.11.1. Sodium tert-isoamylate was prepared via the

reaction of tert-isoamyl alcohol and metallic sodium

in dry toluene. When needed, the solution was evap-

orated from toluene at a reduced pressure of 1 Torr;

residue was dissolved in dry ether.

1

Torr. H NMR (CCl₄, 200 MHz): δ = 0.096 (s, 9H),

δ = 0.035 (s, 3H), δ = 1.74 (d, 4H), δ = 3.62 (m, 4H).

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 537

2.11.2. A solution of diphenylsilanediol (12.0 g,

0.555 mol) with its mixture with ether (100 mL)

and pyridine (5 mL) was added in drops to a stirred

solution of sodium tert-isoamylate (12.76 g, 0.116

mol) in dry ether (100 mL) at –10^◦C. The mixture

was stirred for 1.5 h and heated to 25^◦C. After evapo-

ration of ether, the formed tert-isoamyl alcohol was

removed by azeotropic distillation with toluene. The

precipitated residue of disodiumoxydiphenylsilane

was ﬁltered and dried at a reduced pressure of 1

Torr and at 50^◦C (content of sodium in the residue

was equal to 17.20%; theoretical content, 17.69%),

suspended in dry toluene (85 mL), and treated with

a solution of trimethylchlorosilane (16.4 g, 0.15 mol)

in toluene (50 mL). As a result, we obtained 19.61

g (98% yield) of 3,3-diphenylhexamethyltrisiloxane

(Table 1, no. 19).

of sodium hydroxide (2.0 g, 0.05 mol) in trimethyl-

iso-propoxysilane (19.8 g, 0.15 mol) was stirred at

90^◦C for 4 h. No visible changes in the systems were

detected: system remained heterogeneous. The mix-

ture was evaporated at a reduced pressure of 1 Torr;

the distilled fraction was collected in a liquid nitro-

gen cooled trap. This fraction (19.5 g) was based

on a pure trimethyl-iso-propoxysilane (T_b= 90^◦C,

n²_D⁵= 1.3749).

2.15. Interaction

of

Hexamethyldisiloxane

(HMDS) with Sodium Methylate, Ethylate, and

Isopropylate

2.15.1. Sodium alcoholates were prepared by the in-

teraction of the corresponding alcohol with metallic

sodium in dry toluene.

2.15.2. Suspension of sodium methylate (4.67 g,

0.086 mol) in HMDS (69.80 g, 0.43 mol) was stirred

at 100^◦C for 6 h. No visible changes in the systems

were detected: system remained heterogeneous. The

mixture was evaporated at a reduced pressure of

1 Torr; the distilled fraction was collected in a

liquid nitrogen cooled trap. This distilled fraction

(69.60 g) was based on a pure HDMS (T_b= 100^◦C,

n²_D⁰= 1.3772).

2.15.3. Similar results were obtained when mixtures

of HDMS (46.80 g, 0.29 mol) HMDS with sodium

ethylate (3.92 g, 0.057 mol) and HDMS (40.70 g, 0.25

mol) with sodium isopropylate (4.11 g, 0.05 mol)

were boiled.

2.12. Interaction of Trimethylmethoxysilane

with Sodium Hydroxide (3:1). Sodium hydroxide

(2.6 g, 0.065 mol) was added to trimethylmethoxysi-

lane (20.3 g, 0.195 mol) under stirring at 0^◦C.

Temperature in the system was spontaneously

increased to 30–35^◦C. After a complete homoge-

nization within 3 min, crystalline precipitate of

sodium methylate was obtained. Reaction mixture

was evaporated at a reduced pressure of 1 Torr;

the resulting condensate was collected in a liquid

nitrogen cooled trap. As a result of rectiﬁcation

of the condensate, 10.0 g (95% yield) of hexam-

ethyldisiloxane was obtained. Found: T_b= 4100^◦C,

n²_D⁰= 1.3772.

Solid residue (3.6 g) was treated with a solution

of triethylchlorosilane (10.8 g, 0.072 moles) in dry

n-pentane (40 mL). According to the GLC data, a

mixture based on triethylmethoxysilane (95%) and

1,1,1-triethyl, 3,3,3-trimethyldisiloxane (5%) was

obtained.

2.16. Interaction of (N-methylamino)dimethyl-

ethoxysilane with Sodium Hydroxide (1:1)

2.16.1. Sodium hydroxide (8.0 g, 0.20 mol) was

added to (N-methylamino)dimethylethoxysilane

(26.65 g, 0.20 mol) under stirring at room tempera-

ture. Within 10 min, temperature in the system was

spontaneously increased to 35^◦C, and this led to

an intensive formation of methylamine, which was

titrated by 0.1 N HCl using the Tishchenko titration

cell. The mixture was stirred at 35^◦C for 8 h and

evacuated at a reduced pressure of 1 Torr and at

40^◦C for 1.5 h. White solid residue was dissolved

in dry n-pentane (85 mL); the solution was ﬁltered

from unreacted sodium hydroxide and treated with

a solution of trimethylchlorosilane (23.8 g, 0.22 mol)

in n-pentane (55 mL). As a result, we obtained 30.8 g

(80%) of pentamethylethoxydisiloxane (Table 1,

no. 1).

2.13. Interaction of Trimethylethoxysilane with

Sodium Hydroxide (3:1). Sodium hydroxide (2.0 g,

0.05 mol) was added to a mixture of trimethyl-

ethoxysilane (17.7 g, 0.15 mol) and pyridine (3.9 g,

0.05 mol). The mixture was stirred for 1.5 h at 70^◦C

until its complete homogenization was attained. Liq-

uid components of the system were evaporated at a

reduced pressure of 1 Torr. The residue was dried

by azeotropic distillation with benzene and treated

with a solution of dimethyldichlorosilane (3.2 g,

0.025 mol) in benzene (15 mL). As a result, we ob-

tained 5.70 g (48% yield) of octamethyltrisiloxane

(Table 1, no. 14).

2.16.2. Similar reaction of (N-methylamino)di-

methylethoxysilane (79.9 g, 0.6 mol), sodium hy-

droxide (8.0 g, 0.2 mol), and trimethylchlorosilane

2.14. Interaction of Trimethyl-Iso-Propoxysilane

with Sodium Hydroxide (3:1 ratio). The suspension

Heteroatom Chemistry DOI 10.1002/hc

538 Rebrov and Muzafarov

(23.8 g, 0.22 mol) gave 36.9 g (96% yield) of penta-

methylethoxydisiloxane.

and dried at a reduced pressure of 1 Torr at 50^◦C.

As a result, we obtained 27.0 g of white powder

(%Na = 29.23); after its treatment with a solution

of trimethylchlorosilane (71.6 g, 0.61 mol) and

pyridine (17.4 g, 0.21 mol) in n-hexane (180 mL),

we obtained 17.3 g of hexamethyldisiloxane, 20.2

g (65%) of decamethyltetrasiloxane (Table 1, no.

15), and 2.5 g (10%) of dodecamethylpentasiloxane

(Table 1, no. 16).

2.16.3. Sodiumoxydimethylethoxysilane was synthe-

sized according to procedure 2.16.2 and recrystal-

lized from n-pentane. The formed crystals were ﬁl-

tered, washed with cooled n-pentane, and dried at a

reduced pressure of 1 Torr at 30^◦C. Found: Na 16.10.

1

Calcd: Na 16.19. H NMR (C₆D₆, 200 MHz, internal

reference sample—TMS): δ = 0.343 (s, 6H), δ = 1.338

(t, 3H), δ = 3.750 (q, 2H).

2.20. Interaction of Tetraethoxysilane with

Sodium Hydroxide (1:2). Sodium hydroxide (8.0 g,

0.20 mol) was added to a solution of tetra-

ethoxysilane (20.8 g, 0.10 mol) in toluene (50 mL),

under stirring at 15^◦C. Temperature in the system

was spontaneously increased to 40^◦C. In this case,

the precipitation of a voluminous white solid was

observed. The mixture was stirred at 25^◦C for 3 h

and then heated to 75^◦C. Within 1 h of stirring,

the mixture became fully homogeneous. After treat-

ment with a solution of trimethylchlorosilane (23.0

g, 0.21 mol) and pyridine (17.4 g, 0.21 mol) in

toluene (80 mL) at –40^◦C, we obtained 6.1 g (28.4%)

of 3,3,5,5-tetraethoxyhexamethyltetrasiloxane (Ta-

ble 1, no. 17) and 10.8 g undistillable fractions.

Found: ¹H NMR of undistillable fractions (CCl₄, 200

MHz, internal reference sample—TMS): ratio be-

tween integral intensities of signals from protons of

2.17. Interaction of bis(dimethylamino)di-

methylsilane

with

Sodium

Hydroxide. The

suspension of sodium hydroxide (4.0 g, 0.1 mol) in

bis(dimethylamino)dimethylsilane (43.8 g, 0.6 mol)

was stirred at 120^◦C for 10 h. No visible changes

in the systems were detected: system remained

heterogeneous. The mixture was evaporated at a

reduced pressure of 1 Torr; the distilled fraction

was collected in a liquid nitrogen cooled trap.

The distilled fraction (43.6 g) was based on a

pure bis(dimethylamino)dimethylsilane (T_b= 127^◦C,

n²_D⁵= 1.4158).

2.18. Interaction of Dimethyldiethoxysilane

with Sodium Hydroxide (1:2). Sodium hydrox-

ide (24.0 g, 0.6 mol) was added to a solution of

dimethyldiethoxysilane (44.4 g, 0.3 mol) in dry

toluene (55 mL). The mixture was stirred at 80^◦C

for 1.5 h and at 100^◦C for 1 h. The formed ethanol

was removed from the system by its azeotropic dis-

tillation with toluene. The mixture was evaporated

from toluene at a reduced pressure of 1 Torr; solid

residue was dried at a reduced pressure of 1 Torr

at 50^◦C, suspended in dry n-pentane (120 mL), and

treated with a solution of trimethylchlorosilane

(107.4 g, 0.93 mol) and pyridine (23.7 g, 0.31 mol)

in n-pentane (240 mL). As a result, we obtained

48.0 g of hexamethyldisiloxane, 2.9 g (5%) of

pentamethylethoxydisiloxane (Table 1, no. 1), 30.3 g

(65%) of decamethyltetrasiloxane (Table 1, no. 15),

and 7.7 g (20%) dodecamethylpentasiloxane (Table

1, no. 16).

methyl radical at silicon atoms H_Si(CHδ = 0.05 (s)

)

and ethoxyl groups H_SiOCH

δ = 1.18 ³(t), H_SiOCH

CH

3

2

3

2

δ = 3.68 (q) was equal to 1.7:1. Calcd: for repeat unit

–Si(OC₂H₅)OSi(CH₃)₃1.80: 1.

3. Reactions of Organoalkoxysiloxanes with

Sodium Hydroxide and MSOAS

3.1. Interaction of 1,3-diethoxytetramethyldi-

siloxane with Sodium Hydroxide

3.1.1. Sodium hydroxide (1.8 g, 0.045 mol)

was added to a solution of 1,3-diethoxytetra-

methyldisiloxane (10.0 g, 0.045 mol) in toluene

(25 mL) under stirring at 15^◦C. The mixture was

stirred at room temperature until its complete ho-

mogenization was attained. The formed ethanol was

removed from the system by azeotropic distillation

with toluene at a reduced pressure of 10 Torr and

at 25–30^◦C. White powder residue was suspended in

n-pentane (30 mL) and treated with a solution of

trimethylchlorosilane (5.4 g, 0.05 mol) in n-pentane

(15 mL) at –55^◦C. As a result, we obtained 8.15 g (98%

with respect to the total amount of formed products)

of dodecamethylpentasiloxane (Table 1, no. 16).

2.19. Interaction

of

Sodiumoxydimethyl-

ethoxysilane with Sodium Hydroxide (1:1). Sodium

hydroxide (8.0 g, 0.20 mol) in 70 mL of dry toluene

was added under stirring to a solution of sodi-

umoxydimethylethoxysilane (28.5 g, 0.20 mol)

prepared according to procedure 2.2 (Table 4, no.

1.3). The mixture was stirred at 90 → 100^◦C for

6.5 h. In this case, the precipitation of a volumi-

nous white solid was observed. After azeotropic

drying with toluene, the precipitate was ﬁltered

3.1.2. Sodium hydroxide (2.65 g, 0.066 mol) was

added to 1,3-diethoxytetramethyldisiloxane (44.10 g,

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 539

0.198 mol) under stirring at 15^◦C. The mix-

ture was stirred at 26^◦C until complete homog-

enization was attained; then, the mixture was

evaporated at a reduced pressure of 1 Torr at

30 → 55^◦C. Distilled fraction (25.7 g) was collected in

a liquid nitrogen cooled trap. According to the GLC

data, in addition to ethanol, distilled fraction con-

tained dimethyldiethoxysilane (95%) and initial 1,3-

diethoxytetramethyldisiloxane (5%). The amount of

the formed ethanol agreed with theoretical estimates

(3.1 g).

After evaporation, the resulting residue was dis-

solved in dry n-pentane (80 mL) and treated with

a solution of trimethylchlorosilane (7.9 g, 0.073

mol) in n-pentane (20 mL) at –50^◦C. As a result,

we obtained 8.8 g (69.5%) of pentamethylethoxy-

disiloxane (Table 1, no. 1), 1.7 g (9.7%) of

1-ethoxyheptamethyltrisiloxane (Table 1, no. 20),

and 9.8 g of undistillable fractions.

(17.3 g, 0.159 mol) in n-hexane (40 mL). As a result,

we obtained 1.9 g (7%) of hexamethyldisiloxane,

20.2 g (73%) of octamethyltrisiloxane, 2.7 g (10%) of

decamethyltetrasiloxane, and 2.7 g (10%) of dode-

camethylpentasiloxane. Yields were calculated with

respect to the total amount of isolated trimethylsilyl

derivatives (27.6 g).

3.4. Interaction of 3,3-dimethylhexaethoxytri-

siloxane with Sodium Hydroxide

3.4.1. Synthesis of 3,3-dimethylhexaethoxytrisiloxane.

A solution of dimethyldichlorosilane (33.5 g, 0.26

mol) in n-hexane (80 mL) was added in drops to

a solution of sodiumoxytriethoxysilane (105.0 g,

0.52 mol) prepared according to procedure 2.3 in

dry n-hexane (450 mL) under stirring at −40^◦C.

The mixture was stirred at 25^◦C for 1 h and at

60^◦C for 0.5 h. The precipitated residue of sodium

chloride was ﬁltered and washed with n-hexane;

the resulting ﬁltrate was evaporated from n-hexane;

residue was rectiﬁed at a reduced pressure of 1

Torr. As a result, we obtained 60.7 g (56%) of 3,3-

dimethylhexaethoxytrisiloxane. Found: T_b= 99^◦C/1

Torr, n²_D⁵= 1.3957, d₄²⁵= 0.9946, M_D^R= 100.59. Si

20.48, C 40.33, H 8.58. Calcd: M_D^R= 100.74, Si 20.22,

3.2. Interaction of 1,3-diethoxytetramethyldi-

siloxane

with

Sodiumoxydimethylethoxysilane.

Sodiumoxydimethylethoxysilane (32.0 g, 0.225 mol)

prepared according to procedure 2.2 (Table 4,

no. 1.3) was dissolved in 1,3-diethoxytetra-

methyldisiloxane (50.0 g, 0.225 mol). The solution

was stirred at a reduced pressure of 40 Torr at

55 → 65^◦C for 6 h and then for 1 h at 1 Torr and

at 55^◦C. In this case, we obtained 28.7 g (88%)

of distilled dimethyldiethoxysilane. The result-

ing residue was dissolved in n-hexane (120 mL)

and treated with a solution of trimethylchlorosi-

lane (26.8 g, 0.247 mol) in n-hexane (60 mL) at

–30^◦C. As a result, we obtained 10.8 g (25%) of

pentamethylethoxydisiloxane (Table 1, no. 1),

1

C 40.31, H 8.71. H NMR (CCl₄, 200 MHz, internal

reference sample—TMS): δ = 0.153 (s, 6H), δ = 1.180

(t, 18H), δ = 3.680 (q, 12H).

3.4.2. Suspension of sodium hydroxide (0.98 g,

2.45 × 10⁻²mol) in 3,3-dimethylhexaethoxytri-

siloxane (10.25 g, 2.45 × 10⁻²mol) was stirred at

–35^◦C for 1 h. No visible indications of the reac-

tion were observed. The mixture was stirred at 15^◦C

for 0.5 h until its homogenization was attained.

Volatile reaction products were removed from the

system at a reduced pressure of 1 Torr at 20–25^◦C

and collected in a liquid nitrogen. Distilled frac-

tion contained 1.15 g of mixture of ethanol and

dimethyldiethoxysilane. The resulting residue was

dissolved in n-hexane (35 mL) and treated with a

solution of trimethylchlorosilane (2.9 g, 2.67 × 10⁻²

moles) in n-hexane (15 mL). After vacuum frac-

tionation at 1 Torr, we obtained 2.9 g of mix-

ture of 1,1,1,-trimethyl,3,3,3-triethoxydisiloxane and

tetraethoxysilane. The weight of nonfractionated re-

side was equal to 5.4 g.

4.19

g (7%) of 1-ethoxyheptamethyltrisiloxane

(Table 1, no. 20), 5.33 g (15%) of decamethylte-

trasiloxane (Table 1, no. 15), and 15.2 g (35%) of

dodecamethylpentasiloxane (Table 1, no. 16).

1

1-Ethoxyheptamethyltrisiloxane: H NMR (CCl₄,

200 MHz, internal reference sample—TMS)

δ = 0.377 (s, 6H), δ = 0.400 (s, 6H), δ = 0.486 (s, 9H),

δ = 1.500 (t, 3H), δ = 4.08 (q, 2H).

3.3. Interaction

of

1-methoxypentamethyl-

disiloxane with Sodium Hydroxide. Solid sodium

hydroxide (5.8 g, 0,145 mol) was added to a solu-

tion of 1-methoxypentamethyldisiloxane (28.3 g,

0,159 mol) in toluene (50 mL). The mixture was

stirred at 40^◦C for 3.5 h until a complete homoge-

nization of the system was attained. The solution

was evaporated from toluene at a reduced pressure

of 1 Torr. The resulting residue was colorless viscous

liquid, which was dissolved in n-hexane (55 mL)

and treated with a solution of trimethylchlorosilane

4. Thermal Behavior of MSOAS

4.1. Thermal Degradation of Sodiumoxydi-

methylethoxysilane

4.1.1. Stirred melt of sodiumoxydimethyl-

ethoxysilane (T_b= 70^◦C) (56.9 g, 0.40 mol) was

Heteroatom Chemistry DOI 10.1002/hc

540 Rebrov and Muzafarov

slowly heated under argon from 70 to 200^◦C.

At 185–190^◦C, an intensive thermal degradation

was accompanied by the release of volatile liquid

products, which were collected in an ice-cooled trap.

After thermal degradation, the system was heated

at a reduced pressure of 1 Torr at 190^◦C for 1 h.

Condensate was collected in a liquid nitrogen cooled

trap. In total, we obtained 19.1 g of degradation

products, which were fully distilled at 45–130^◦C. Ac-

cording to the GLC data, the condensate contained

two compounds: trimethylethoxysilane (95%) and

dimethyldiethoxysilane (5%).

After thermal degradation, solid residue (31.3 g,

%Na = 27.2) was suspended in n-pentane (130 mL)

and treated with a solution of trimethylchlorosi-

lane (44.2 g, 0.41 mol) in n-pentane (100 mL) at

−30^◦C. As a result, we obtained 40.7 g of trimethylsi-

lyl derivatives, which involved 5.90 g (14.6%) of

trimethylethoxysilane, 2.80 g (6.9%) of hexamethyl-

disiloxane, 1.91 g (4.7%) of octamethyltrisiloxane,

1.02 g (2.5%) of pentamethylethoxydisiloxane, and

29.07 g of distilled fractions.

1.5 g of 3,3,5,5-tetraethoxyhexamethyltetrasiloxane

(Table 1, no. 17) and 2.3 g of high-boiling liquid frac-

tions (T_b> 350^◦C). Unreacted precipitate was washed

with dimethylsulfoxide to remove sodium chloride;

as a result, we obtained 13.2 g of white powder

(%Na = 12.1).

REFERENCES

[1] Rebrov, E. A.; Muzafarov, A. M.; Zhdanov, A. A. Dokl

Akad Nauk SSSR 1988, 302(2), 346–348.

[2] Rebrov, E. A.; Muzafarov, A. M.; Papkov, V. S.;

Zhdanov, A. A. Dokl Akad Nauk SSSR 1989, 309(2),

376–380.

[3] Sommer, L. H.; Green, L. Q.; Whitemore, F. C. J Am

Chem Soc 1949, 71, 3253–3254.

[4] Takiguchi, T.; Abe, M.; Takahashi, K.; Urano, K. Bull

Chem Soc Japan 1966, 39(3), 619–620.

[5] Takiguchi, T.; Abe, M.; Urano, K.; Sakuma, T. Bull

Chem Soc Japan 1967, 40(10), 2453–2454.

[6] Kelvin, F.; MeCombs, M.; Frank P. US Patent

3932686, 1976; Chem Abstr 1976, 84, 122864q.

[7] Shigemi, K.; Sadaomi, F. J Chem Soc Japan, Ind

Chem Sec 1960, 63(6), 1019–1021.

[8] Boury, B.; Corriu, R. J. P.; Le Strat, V.; Nun˜ez, R.

J Chem Soc, Dalton Trans 1999, 4535–4540.

[9] Hyde, J. F. J Am Chem Soc 1953, 75(9), 2166–

2167.

[10] Andrianov, K. A.; Zavin, B. G. Zh Neorganicheskoy

Khim 1967, 12(8), 2261–2266.

[11] Andrianov, K. A.; Zavin, B. G. Izv Akad Nauk SSSR

Ser Neorg Mater 1966, 2(5), 881–885.

[12] Muzafarov, A. M.; Rebrov, E. A. VI Vsesoyuznaya

Konferensiya po Chimii i Primeneniyu Kremni-

jorganicheskich Soedinenij, Riga 1986. Abstracts,

pp. 199–200.

[13] Kather, W. S.; Torkelson, A. Ind Ingien Chem 1954,

46(2), 381–384.

[14] Bartholin, M.; Guyot, A. Compties Rendus 1967,

264(21C), 1694–1696.

[15] Fromberg, M. B.; Petrashko, Yu. K.; Voshzova, V. D.;

Andrianov, K. A. Izv Akad Nauk SSSR Ser Khim 1965,

4, 660–665.

4.1.2. Solution of sodiumoxydimethylethoxysilane

(28.44 g, 0.20 moles) in n-undecane (100 mL)

was stirred at 185–190^◦C for 7 h. According to

the GLC data, distilled fraction (9.20 g) contained

trimethylethoxysilane (95%) and dimethyldiethoxy-

silane (5%).

The precipitated residue was ﬁltered, washed

with dry n-hexane, and dried at a reduced pressure

of 1 Torr at 60^◦C. The resulting white powder

(16.20 g, %Na = 26.9) was suspended in dry n-

pentane (75 mL), and treated with a solution of

trimethylchlorosilane (23.9 g, 0.22 mol) in n-pentane

(50 mL) at –30^◦C. As a result, we obtained 20.9 g

of trimethylsilyl derivatives, which contained 3.10 g

(14.8%) of trimethylethoxysilane, 1.40 g (6.7%) of

hexamethyldisiloxane, 0.90 g (4.3%) of octamethyl-

trisiloxane, 1.00 g (4.8%) of pentamethylethoxydis-

iloxane, and 14.50 g of distilled fractions.

[16] Izmaiylov, B. A.; Zhdanov, A. A. Zh Obsch Khim 1982,

52(3), 642–646.

[17] Andrianov, K. A.; Zhdanov, A. A. Dokl Akad Nauk

SSSR 1957, 114(5), 1005–1007.

[18] Zhdanov, A. A.; Andrianov, K. A.; Fetisov, G. A.;

Isaeva, L. M. Visokomolek Soed 1967, 9A(12), 2620–

2623.

[19] Zhdanov, A. A.; Andrianov, K. A.; Levitskij, M. M. Izv

Akad Nauk SSSR Ser Khim 1974, 3, 653–657.

[20] Zhdanov, A. A.; Levitskij, M. M.; Dubchak, I. L.;

Shilkloper, O. Yu. Izv Akad Nauk SSSR Ser Khim

1985, 1, 237–238.

[21] Andrianov, K. A. Dokl Akad Nauk SSSR 1961, 140(6),

1310–1313.

[22] Petrashko, A. I.; Andrianov, K. A. Visokomolek Soed

1962, 4(2), 221–229.

[23] Andrianov, K. A.; Volkova, Lora M.; Tartakovskaya,

L. M. Izv Akad Nauk SSSR Otd Khim Nauk 1963, 2,

294–298.

4.2. Thermal Degradation of Sodiumoxytri-

ethoxysilane. Solution of sodiumoxytriethoxysilane

(35.8 g, 0.178 mol) in n-undecane (100 mL) was

stirred at 180–190^◦C with slow distillation of the

mixture of n-undecane and formed tetraethoxysi-

lane for 20 h. In total, 15.8 g of tetraethoxysi-

lane was obtained. The precipitated residue was ﬁl-

tered, washed with dry n-pentane, and dried at a

reduced pressure of 1 Torr at 100^◦C (%Na = 20.5).

The suspension of the resulting powder in

n-pentane (70 mL) was treated with a solution

of trimethylchlorosilane (21.2 g, 0.195 mol) in

n-pentane (45 mL) at 35^◦C. As a result, we obtained

Heteroatom Chemistry DOI 10.1002/hc

Monosodiumoxyorganoalkoxysilanes: Synthesis and Properties 541

[24] Andrianov, K. A.; Emelyanov, V. N.; Rabkina, A. Yu.;

Leytes, L. A. Izv Akad Nauk SSSR Ser Khim 1967, 12,

2666–2672.

[25] Avilova, T. P.; Bikov, V. T.; Bessonova, V. I.

Vysokomolek Soed 1969, 11B(11), 847–849.

[26] Andrianov, K. A.; Chananashvili, L. M.; Minakov,

V. T.; Gashnikova, N. P. Izv Akad Nauk SSSR Ser

Khim 1970, 10, 2276–2280.

[27] Kolesnikov, I. M.; Panchenkov, G. M.; Andrianov,

K. A.; Zhdanov, A. A.; Belov, N. I.; Levitskij,

M. M. Izv Akad Nauk SSSR Ser Khim 1974, 2,

488–489.

[47] Voronkov, M. G.; Basenko, S. V.; Vitkovskij, V. Yu.;

Nozdrya, S. M.; Mirskov, R. G. Metallorganicheskaya

Khim 1989, 2(2), 310–313.

[48] Klingebiel, U. Chem Ber 1981, 114, 3366–3371.

[49] Ruehmann, K.; Wagner, S.; Wenzel, R.; Lehnert, R.;

Scheim, U. GDR Patent DD 234679, 1986; Chem Ab-

str 1986, 105, 209195y.

[50] Bashant, V.; Chavalpvski, V.; Ratouski, I. Silikoni;

Goschimizdat: Moscow, 1960; p. 169.

[51] Wojnowski, W.; Bochenska, W.; Peters, K.; Eva, M.;

Von Schnering. Z Anorg Allg Chem 1986, 533, 165–

174.

[28] Zhdanov, A. A.; Andrianov, K. A.; Levitskij, M. M. Izv

Akad Nauk SSSR Ser Khim 1976, 2, 395–399.

[29] Shapkin, N. P.; Alikovskij, A. V.; Shapkina, V. Ya.

Zh Obsch Khim 1987, 57(2), 321–329.

[30] Shchegolikhina, O.; Pozdniakova, Yu.; Antipin,

M.; Katsoulis, D.; Auner, N.; Herrschaft, B.

Organometallics 2000, 19, 1077–1082.

[52] Sommer, L. Stereochemistry and Reaction Mech-

anism of Organosilicon Compounds; Izd Mir:

Moscow, 1966.

[53] Ghaffee, R. G. US Patent 3280073, 1966; Chem Abstr

1967, 66, 38337r.

[54] Kolditz, L.; Preiss, H. Z Anorg Allg Chem 1963, 325,

245–251.

[31] Shchegolikhina, O. I.; Pozdnyakova, Yu. A.;

Molodtsova, Yu. A.; Korkin, S. D.; Bukalov, S. S.;

Leites, L. A.; Lyssenko, K. A.; Peregudov, A. S.; Auner,

N.; Katsoulis, D. E. Inorg Chem 2002, 41(25), 6892–

6904.

[32] Pozdniakova, Yu. A.; Lyssenko, K. A.; Korlyukov,

A. A.; Blagodatskikh, I. V.; Auner, N.; Katsoulis, D.;

Shchegolikhina, O. I. Eur J Inorg Chem 2004, 1253–

1261.

[33] Matukhina, E. V.; Shchegolikhina, O. I.; Molodtsova,

Yu. A.; Pozdnyakova, Yu. A.; Lyssenko, K. A.; Vasil’ev,

V. G.; Buzin, M. I. Liq Cryst 2004, 31(3), 401–

420.

[34] Yoshimoto, A.; Ichiro K. Bull Chem Soc Japan 1969,

42(4), 1118–1123.

[35] Wright, J. R.; Bolt, R. O.; Goldshmidt, A.; Abbott,

A. D. J Am Chem Soc 1958, 80(7), 1733–1737.

[36] Wojnowski, W. Z Anorg Allg Chem 1974, 403, 186–

192.

[37] Schott, G.; Engelbrecht, L.; Holdt, H. J. Z Anorg Allg

Chem 1979, 459, 177–186.

[55] Andrianov, K. A.; Zhdanov, A. A.; Kurasheva, N. A.;

Chinku, E. C.; Lavruchin, B. D. Izv Akad Nauk SSSR

Ser Khim 1974(4), 950–952.

[56] Voronkov, M. G.; Zhagata, A. A. Zh Obsch Khim 1967,

37(11), 2551–2553.

[57] Scherbakov, V. I.; Basova, G. V.; Chorshev, S. Ya.;

Malisheva, I. P.; Domrachev, G. A. Zh Obsch Khim

2002, 72(3), 423–426.

[58] Domrachev, G. A.; Scherbakov, V. I.; Basova, G. V.;

Malisheva, I. P.; Matveev, A. P.; Vasilevskaya, I. L. Zh

Obsch Khim 1999, 69(9), 1466–1469.

[59] Scherbakov, V. I.; Basova, G. V.; Stepovik, L. P.

Domrachev, G. A. Zh Obsch Khim 1995, 65(4), 612–

615.

[60] Hoenigaschmid-Grossich, R.; Rogler, W.; Joch, W.

West Germany Patent 2048018, 1972; Chem Abstr

1972, 77, 10077k.

[61] Termin, E.; Joch, W.; Rogler, W. West Germany

Patent 1954830, 1971. Chem Abstr 1971, 75, 63120h.

[62] Andrianov, K. A.; Sirtsova, Zh. S.; Kopilov, V. M. Zh

Obsch Khim 1970, 40(7), 1665–1666.

[38] Juergen, H. H.; Guenther, S.; Popowski, E.; Kelling,

H. Z Chem 1983, 23(7), 252.

[39] Andrianov, K. A.; Zhdanov, A. A.; Kurasheva, N. A.;

Chinku, E. C. Izv Akad Nauk SSSR Ser Khim 1977,

(9), 2115–2116.

[40] Knollmueller, K. O. US Patent 4207247, 1980; Chem

Abstr 1980, 93, 185753j.

[63] Jones, D. N. (Ed.). Comprehensive Organic Chem-

istry, Vol.: 3. Selenium, Silicon, Boron, Compounds.

Pergamon Press: London, 1979.

[64] Baz´ant, B.; Chvalovsky´, V.; Rathousky´, J. Register of

Organosilicon Compounds, Prague, 1973–1983.

[65] Salinger, F.; Klosowski, F.; De Young. J Org Chem

1970, 35(5), 1308–1314.

[41] Knollmueller, K. O. US Patent 4294713, 1982; Chem

Abstr 1982, 96, 9248b.

[42] Knollmueller, K. O. US Patent 4329485, 1982; Chem

Abstr 1982, 97, 72576t.

[43] Knollmueller, K. O. US Patent 4329486, 1982; Chem

Abstr 1982, 97, 110186a.

[44] Bashant, V.; Chavalpvski, V.; Ratouski, I. Silikoni;

Goschimizdat: Moscow, 1960, pp. 126, 195–196.

[45] Reychsfeld, V. O.; Chanchodshaeva, D. A. Avtorskoe

Svid SSSR no. 739072, 1980; Otkritiya Izobr 1980,

no. 21, 137.

[46] Chanchodshaeva, D. A.; Saratov, I. E.; Reychs-

feld, V. O.; Lazarev, S.Ya.; Shlyakova, N. R.

Trudi V. Soveshyaniya po Chimii I Prakticheskomu

Primeneniyu Kremnijorganicheskich Soedinenij; Izd

Nauka: Leningradskoe Otd, 1984; pp. 110–111.

[66] Dervan, P. V.; Shippey, M. A. J Am Chem Soc 1976,

98(5), 1265–1267.

[67] Corriu, R.; Gue`rin, C.; Henner, B.; Wang, Q.

J Organomet Chem 1989, 365(3), C7–C10.

[68] Talalaeva, T. V.; Zenina, G. V.; Kocheshkova, K. A.

Dokl Akad Nauk SSSR 1966, 171, 122–124.

[69] Andrianov, K. A.; Zhdanov, A. A.; Evdokimov, A. M.;

Levitskij, M. M. Izv Akad Nauk SSSR Ser Khim 1971,

6, 1360–1361.

[70] Boury, B.; Corriu, R. J. P.; Le Strat, V.; Nun˜ez, R. J

Chem Soc, Dalton Trans 1999, 4535–4540.

[71] Gordon, A. J.; Ford, R. A. The Chemist’s Compan-

ion. A Handbook of Practical Data, Techniques and

References; Wiley-Interscience: New York, 1972.

[72] Andrianov, K. A. Metodi Elementoorganicheskoy

Chimii; Kremnij: Moscow, 1968.

Heteroatom Chemistry DOI 10.1002/hc

Article Doi

Monosodiumoxyorganoalkoxysilanes: Synthesis and properties

DOI: 10.1002/hc.20280

Source and publish data:

Authors:

Article abstract of DOI:10.1002/hc.20280

Full text of DOI:10.1002/hc.20280

Products guided by the article

R&D Labs maybe for 13176-70-0

Relevant to this article

Hot Product