Reaction of γ-(aminopropyl)siloxanes with phenolphthalein as a route to new siloxane-containing phenols

Article abstract of DOI:10.1134/S1070427214020141

The reaction of γ-aminopropylorganosiloxanes with phenolphthalein yields monomeric and oligomeric N-alkylsiloxy-3,3-bis(4-hydroxyphenyl) phthalimidines. Their structures and compositions were confirmed by IR and NMR spectroscopy and by HPLC-MS. Studies by GLC and MALDI mass spectrometry showed that the action of the amine and of the water released in the reaction leads to the rearrangement of the siloxane bond in the course of the synthesis with the formation of linear and cyclic carbofunctional oligomeric siloxanephenols and mixed oligophenolaminosiloxanes. The possibility of modification of epoxy resins with the synthesized oligomers was revealed.

Full text of DOI:10.1134/S1070427214020141

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2014, Vol. 87, No. 2, pp. 207−213. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © D.O. Anashkin, I.M. Raigorodskii, V.M. Kopylov, V.A. Kovyazin, V.V. Boev, V.N. Sokolik, 2014, published in Zhurnal Prikladnoi Khimii,
2014, Vol. 87, No. 2, pp. 227−233.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Reaction of γ-(Aminopropyl)siloxanes with Phenolphthalein
as a Route to New Siloxane-containing Phenols
D. O. Anashkina, I. M. Raigorodskiib, V. M. Kopylovb, V. A. Kovyazinb,
V. V. Boevb, and V. N. Sokolikb
a Lomonosov Moscow State University of Fine Chemical Technologies, pr. Vernadskogo 86, Moscow, 119571 Russia
b Penta-91 Limited Liability Company, Volgogradskii pr., Moscow, 109216 Russia
e-mail: dianol86@yandex.ru
Received May 18, 2013
Abstract—The reaction of γ-aminopropylorganosiloxanes with phenolphthalein yields monomeric and oligomeric
N-alkylsiloxy-3,3-bis(4-hydroxyphenyl)phthalimidines. Their structures and compositions were confirmed by
IR and NMR spectroscopy and by HPLC–MS. Studies by GLC and MALDI mass spectrometry showed that the
action of the amine and of the water released in the reaction leads to the rearrangement of the siloxane bond in
the course of the synthesis with the formation of linear and cyclic carbofunctional oligomeric siloxanephenols
and mixed oligophenolaminosiloxanes. The possibility of modification of epoxy resins with the synthesized
oligomers was revealed.
DOI: 10.1134/S1070427214020141
Carbofunctional siloxane-containing phenols (CSPs)
are demanded monomeric and oligomeric organosili-
con compounds for the synthesis of copolymers [1] and
block copolymers [2, 3] and for modification of organic
polymers [4, 5]. CSP-based copolymers have diverse
applications. They are used as modifiers of commercial
polycarbonates and as materials for high-performance
gas-permeable and pervaporation membranes, electro-
technical coatings, adhesive films for triplex, and con-
ducting matrices for current sources, and also as various
materials for medicobiological purpose [6].
tion of vinylphenoxyhydridosilanes to cyclic products,
followed by hydrolysis to obtain the desired organosili-
con phenols.
Continuing the search for facile routes to new CSPs,
which are of interest as monomers for polycondensation
copolymers and as modifiers for organic resins and
polymers, we studied possible procedures for preparing
phenols with a grafted siloxane group.
RESULTS AND DISCUSSION
The first representatives of organosilicon phenols
with the Si–aryl bond were prepared by Speier et al.
[7] by organometallic synthesis from halophenoxysilyl-
chlorosilanes and chlorosilanes with the subsequent hy-
drolysis of the reaction products to the desired phenols.
Later, such phenols were prepared by hydrosilation of
alkenylphenols with hydridosilanes in the presence of
H2PtCl6 as catalyst [8]. After that, the hydrosilation re-
action was successfully applied to the synthesis of CSPs
from unsaturated phenols or their silyl ethers and hydri-
doorganosilanes [9–12]. Mironov et al. [13] also sug-
gested preparation of CSPs by intramolecular hydrosila-
For our experiments we chose γ-aminopropylorgano-
siloxanes and phenolphthalein, which is a readily
available compound containing, along with two phenoxy
groups, also a reactive lactone functional group.
It is known [14–16] that reactions of phenolphthalein
with primary organic amines yield N-phthalimidines.
However, we found no data on the corresponding
reactions with organosilicon amines.
We expected that the use of aminoalkylsiloxanes in
reaction with phenolphthalein would yield siloxane-
containing bisphenols:
207

208
ANASHKIN et al.
–H2O
The reaction of γ-(aminopropyl)pentamethyl-
sponds to N-(3-[(γ-aminopropyl)tetramethyldisiloxy]-
propyl)-3,3-bis(4-hydroxyphenyl)phthalimidine.
disiloxane with phenolphthalein was performed in
dioxane and o-dichlorobenzene solutions. The reaction
progress was monitored by IR spectroscopy and by the
amount of low-boiling products collected in the Dean–
Stark trap. In the course of the reaction, the intensity of
the absorption band of the C=O bond in phenolphthalein
at 1760 cm–1 decreases and a new absorption band of
the C=O bond on phthalimidine appears at 1660 cm–1
(Fig. 1).
ProductII. Molecularweight(massspectrum)433.1;
soluble in dioxane, acetone, and ethanol; corresponds
to N-[3-(hydroxydimethylsilyl)propyl]-3,3-bis(4-hydr-
oxyphenyl)phthalimidine.
Product III. Molecular weight (mass spectrum)
318.2, the NMR spectrum corresponds to the initial
phenolphthalein.
Product IV. Molecular weight (mass spectrum)
847.4; poorly soluble in acetone and ethanol, soluble
in dioxane and DMSO; corresponds to 1,3-bis([3,3-
bis(4-hydroxyphenyl)phthalimidin-2-yl]propyl)tetra-
methyldisiloxane.
The reaction in dioxane (100°С) is slow. In 40 h, the
conversion, as judged from changes in the intensities of
the absorption bands at 1660 and 1760 cm–1, did not ex-
ceed 10%.
With o-dichlorobenzene used as solvent, the conver-
sion of the lactone carbonyl group into imidine group
in 30 h at 140°С was 90–95%. Similar results were ob-
tained when analyzing the reaction mixture by NMR
(Fig. 2).
Product V. Molecular weight (mass spectrum) 505.5;
soluble in dioxane, acetone, and ethanol; corresponds to
the desired N-[3-(pentamethyldisiloxy)propyl]-3,3-bis-
(4-hydroxyphenyl)phthalimidine.
Compounds I–IV can be formed by rearrangement
upon cleavage of the siloxane bond with the water
released in the course of the reaction (Scheme 1).
A GLC analysis of the low-boiling products
revealed the presence of water, solvent, initial amine,
and hexamethyldisiloxane. The presence of the latter
suggests cleavage of the siloxane moiety. Similar
rearrangements of siloxanes under the action of amines
in the presence of proton-donor compounds (water)
were described in [17].
An NMR analysis showed that the ratio of the integral
intensities of the proton signals of the CH3–Si (–0.1
to 0.1 ppm) and phthalimidine (7.3–7.8 ppm) groups
decreased from 15 : 4 [for the product of reaction (1)] to
9 : 4 (for final reaction products). In the NMR spectrum,
there are five signals from CH3–Si≡ protons instead of
two signals [≡C–Si(CH3)2O– and –OSi(CH3)3], which
suggests the presence of several compounds in the
reaction mixture.
An HPLC–MS analysis of the reaction mixture
revealed five major components (Fig. 3). The isolated
compounds were studied by 1H NMR (products I–V).
ν, cm–1
Fig. 1. IR spectrum of the products synthesized in
(1) dioxane and (2) dichlorobenzene. (D) Optical density and
(ν) wavenumber.
Product I. Molecular weight (mass spectrum) 548.6;
soluble in dioxane, acetone, ethanol, and THF; corre-
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REACTION OF γ-(AMINOPROPYL)SILOXANES
209
δ, ppm
Fig. 2. NMR spectrum of products formed in the reaction of (γ-aminopropyl)pentamethyldisiloxane with phenolphthalein in o-di-
chlorobenzene. (δ) Chemical shift.
Scheme 1.
CH3
CH3
+ CH3 Si O Si
CH3
(CH2)3
NH2
CH3
I
−(CH3)3SiOSi(CH3)3
−H2O
IV
V
+ H2O
II
The reaction of 3-(γ-aminopropyl)heptamethyl-
trisiloxane with phenolphthalein was performed in
an o-dichlorobenzene solution for 20 h at 140°С. The
phenolphthalein conversion was 65% according to NMR
data. The reaction yields a series of mixed oligomeric
phenolaminosiloxanes. For example, in the MALDI
mass spectrum (Fig. 4), there are peaks belonging to
linear α,ω-bistrimethylsiloxy oligomers VI with MW =
89 + 417n + 117m + 73, to linear silanols VII with
MW = 89 + 417n + 117(m + 1), to cyclic products VIII
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ANASHKIN et al.
IV
II
I III
V
τ, min
II
I
IV
V
δ, ppm
Fig. 3. Chromatogram of a mixture of products formed in the reaction of γ-(aminopropyl)pentamethyldisiloxane with phenolphthalein
and NMR spectra opf products I, II, IV, and V. (τ) Retention time and (δ) chemical shift.
with MW = 417n + 117m, and to linear bissilanols IX
with MW = 17 + 417n + 117(m + 1) (Scheme 2).
Compounds of structure VI were tested as modifier
for a hot-curable epoxy compound. The TGA data
showed that, on heating of the epoxy compound based
on ED-20 epoxy resin and organosilicon modifier in air,
the onset of the weight loss (5%) occurs above 350°С.
In the MALDI spectrum, there are also signals
corresponding to ionized fragments of the molecules (in
all the cases, m + n = 0–7) (Scheme 3).
Scheme 2.
X
XI
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REACTION OF γ-(AMINOPROPYL)SILOXANES
211
Scheme 3.
VI
VII
IX
VIII
Thus, the reactions of γ-aminopropylsiloxanes with
phenolphthalein yield N-alkylsiloxy-3,3-bis(4-hydroxy-
phenyl)phthalimidines. The phenolphthalein conversion
under the synthesis conditions reaches 95%.
The purity of organosilicon amines and reaction
products was evaluated by gas–liquid chromatography
using a Kristallyuks 4000M chromatograph.
MALDImeasurementswereperformedwitha Bruker
Ultraflex TOF/TOF spectrometer. The ScoutMTP
MALDI ion source is equipped with a nitrogen laser
(wavelength 337 nm) and PAN ion focusing system.
Hydroxybenzoic acid was used as matrix. The target
was prepared from an acetonitrile solution.
The siloxane fragments undergo rearrangements
when heated in the presence of amino groups and of
water released in the reaction. These rearrangements
yield carbofunctional oligophenol(amino)siloxanes of
different structures.
New di- and polyfunctional siloxanes containing
aminopropyl and [3,3-bis(4-hydroxyphenyl)phthalim-
idin-2-yl]propyl groups were obtained and isolated by
HPLC.
High-performance liquid chromatography was
performed with a Vyodaс С18 120А 250 × 4.6 mm
column using a UV detector (220 nm). The mixture
being analyzed was injected into the chromatograph as
solution in acetonitrile. An acetonitrile–water mixture
was used as eluent. The acetonitrile concentration was
varied in the gradient from 5 to 100% in 30 min.
The polyfunctional amino- and phenolsiloxanes can
be effective modifiers for epoxy resins.
EXPERIMENTAL
The initial (γ-aminopropyl)pentamethyldisiloxane
The Fourier transform IR spectra were recorded with
a Nicolet 380 spectrometer in the range 400–4000 cm–1
at room temperature in the transmission mode using
KBr pellets.
The 1H NMR spectra of the products were recorded
with a Bruker AT spectrometer operating at 360 MHz.
CDCl3 was used as solvent for organosilicon amines,
and DMSO-d6, for N-alkylsiloxyphthalimidines.
was prepared in a 1-L two-necked flask equipped
with a stirrer and a reflux condenser. The flask was
charged with 124 g (0.5 mol) of bis(γ-aminopropyl)-
tetramethyldisiloxane and 243 g (1.5 mol) of
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ANASHKIN et al.
Fig. 4. MALDI mass spectrum of a mixture of products formed in the reaction of (γ-aminopropyl)heptamethyltrisiloxane with
phenolphthalein. (I) Intensity.
released in the reaction). The Dean–Stark trap was filled
with toluene. The reaction was performed at 140°С for
30 h. Toluene, dichlorobenzene, and excess amine were
distilled off on a rotary evaporator at 140°С/2 mmHg.
A powdered product (49 g) was obtained. The
phenolphthalein conversion was 95%.
hexamethyldisiloxane in the presence of 0.468 g of
potassium siloxanolate. The reaction was performed at
90°С for 6 h. The reaction progress was monitored by
gas chromatography. The diamine conversion was about
70%. The mixture was distilled at 95–105°С/2 mmHg to
obtain 48.7 g of the product. The amine was analyzed by
GLC. Purity 98.5%. 1H NMR spectrum (DMSO-d6), δ,
ppm: 1.11 (H1), 2.47–2.50 (H2), 1.27–1.39 (H3), 0.40–
0.45 (H4), –0.04 (H5), –0.02 (H6).
The reaction of phenolphthalein with 3-(γ-amino-
propyl)heptamethyltrisiloxane was performed in
a 250-mL four-necked flask purged with nitrogen and
equipped with a stirrer, a thermometer, and a Dean–Stark
trap. The flask was charged with 15.9 g (0.05 mol) of
phenolphthalein, 27.96g(0.1mol)of3-(γ-aminopropyl)-
heptamethyltrisiloxane, 50 mL of dichlorobenzene, and
10 mL of toluene (for azeotropic distillation of the water
released in the reaction). The Dean–Stark trap was filled
with toluene. The reaction was performed at 140°С for
20 h. The phenolphthalein conversion was 65%.
The initial 3-(γ-aminopropyl)heptamethyltrisiloxane
was prepared by the procedure described in [18]. The
purity of the amine, determined by GLC, was 99%.
1
The product was characterized by H NMR, δ, ppm:
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