Reactions of bielectrophiles (ClCH2CH2)2Y with sulfur in basic reducing systems

Article abstract of DOI:10.1023/A:1015425702523

A simple procedure was developed for preparing bis(β-mercaptoethyl) ether and bis(β-mecraptoethyl) sulfide from commercially available chemicals: elemental sulfur, alkali, and bis(β-chloroethyl) ether or sulfide, based on thiylation with elemental sulfur of these substrates in the aqueous system hydrazine hydrate-alkali, with initial formation of the corresponding polysulfide polymers (thiokols). Their reduction with the system hydrazine hydrate-alkali, followed by acidification of dithiolate anions, yields the corresponding dithiols. Thiokols based on bis(β-chloroethyl) ether are soluble in organic solvents; they were studied by ¹H NMR.

Full text of DOI:10.1023/A:1015425702523

Russian Journal of General Chemistry, Vol. 72, No. 2, 2002, pp. 240 243. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 2, 2002,
pp. 260 263.
Original Russian Text Copyright
2002 by Korchevin, Russavskaya, Alekminskaya, Deryagina.
Reactions of Bielectrophiles (ClCH2CH2)2Y with Sulfur
in Basic Reducing Systems
N. A. Korchevin, N. V. Russavskaya, O. V. Alekminskaya, and E. N. Deryagina
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, Russia
Received May 29, 2000
Abstract A simple procedure was developed for preparing bis( -mercaptoethyl) ether and bis( -mecrapto-
ethyl) sulfide from commercially available chemicals: elemental sulfur, alkali, and bis( -chloroethyl) ether or
sulfide, based on thiylation with elemental sulfur of these substrates in the aqueous system hydrazine hydrate
alkali, with initial formation of the corresponding polysulfide polymers (thiokols). Their reduction with the
system hydrazine hydrate alkali, followed by acidification of dithiolate anions, yields the corresponding dithi-
1
ols. Thiokols based on bis( -chloroethyl) ether are soluble in organic solvents; they were studied by H NMR.
We have shown previously that 1,2-dichloroethane
reacts with sulfur in the system NaOH N2H4 H2O
H2O to form thiokol [SCH2CH2S]n, which is subse-
quently reduced in the system hydrazine hydrate alka-
li to the corresponding bisthiolate anion. Treatment of
the latter with HCl yields 1,2-ethanedithiol [1]. The
system hydrazine hydrate alkali readily cleaves both
cyclic S8 molecules to give polysulfide anions Sn2
(n = 1 4) [2] and the S S bond in organic disulfides
R2S2 to give thiolate anions RS [3].
Polymers IIa are viscous oily substances readily
soluble in chloroform. This fact allowed us to study
1
for the first time the H NMR spectra of polysulfide
polymers prepared by thiylation of bielectrophiles
1
with polysulfide anions. The H NMR spectrum of
polymers IIa contains two groups of signals. A down-
field multiplet centered at 3.74 ppm corresponds to
the overlapping signals of the CH2 Cl and CH2 O
protons, present also in the initial ether Ia (multiplet
centered at 3.71 ppm). In the upper field, there are
three triplets which, basing on data in [5], were as-
signed as follows (ppm): 2.61, to CH2S C; 2.89, to
CH2S2 C; and 3.10, to CH2S3 C. These signals indi-
cate that molecules of polymers IIa contain mono-,
di-, and trisulfide units. The nature of polysulfide
anions formed by dissolution of sulfur in the system
aqueous hydrazine hydrate alkali is determined by the
ratio MOH : S : N2H4, and also by the dissolution
conditions [3]. However, the system prepared by reac-
tion (1) is undoubtedly characterized by the equilib-
rium
In view of the fact that organic dithiols are precur-
sors of macrocyclic thiocrown ether systems [4], we
performed the reactions of sulfur in the basic reducing
systems with bielectrophiles (ClCH2CH2)2Y (Y = O,
S) (Ia, Ib) with the aim to prepare the corresponding
dithiols. Furthermore, transformations of Ib, which is
a war gas (yperite), may open up new possibilities for
its utilization.
We found that both compounds Ia and Ib readily
react with a solution of sulfur in the system aqueous
hydrazine hydrate alkali with complete conversion
and formation of polymeric polysulfides II of thiokol
type:
S2
S22
S32
S2n .
(3)
In syntheses of polymers IIa, we took in all cases
the ratio MOH : S 1 : 1, which should result in pre-
ferential formation of disulfides M2S2. With 5 ml of
hydrazine hydrate taken in reaction (1), the ratio of the
S1, S2, and S3 fragments in polymer IIa, according
S8 + 8MOH + 2NH2NH2 H2O
4M2S2 + 2N2 + 9H2O,
(1)
(2)
1
to the H NMR spectrum, is 1 : 2 : 1. With 1 ml of
ClCH2CH2YCH2CH2Cl + M2S2
hydrazine hydrate, this ratio changes to 1 : 1.7 : 1.7,
i.e., equilibrium (3) is shifted to the right. In this case,
alkylation with the equivalent amount of ether Ia
should yield a polymer with a lower molecular weight.
Analysis of the polymers for residual chlorine allowed
Ia, Ib
[SCH2CH2YCH2CH2S]n ,
2MCl
IIa, IIb
M = K, Na; Y = O (a), S (b).
1070-3632/02/7202-0240$27.00 2002 MAIK Nauka/Interperiodica

REACTIONS OF BIELECTROPHILES (ClCH2CH2)2Y WITH SULFUR IN BASIC REDUCING SYSTEMS 241
evaluation of their molecular weight by the method of
terminal groups [6]. Polymer IIa prepared in the pres-
ence of 5 ml of hydrazine hydrate has the molecular
weight of 1800, and that prepared in the presence of
1 ml of hydrazine hydrate, 820.
The yields of dithiols IIIa and IIIb are low: 25 and
34%, respectively. This may be due to the presence in
polymer chains of the sulfide fragments CH2CH2
SCH2CH2 (owing to participation of monosulfides
M2S in the polycondensation), which are not notice-
ably reduced under conditions of reaction (6). Further-
more, in the course of reduction of IIa the arising
dithiolate IVa partially undergoes intramolecular
cyclization to 1,4-oxathiane V (yield up to 20%). Di-
thiolate IVb does not undergo heterocyclization to
1,4-dithiane under similar conditions.
Reaction (2) with sulfide Ib yields polymer IIb,
which is insoluble in organic solvents. Its molecular
weight is 4400. The properties of IIb resemble those
of thiokols prepared by thiylation of dichloroethane
with solutions of sulfur in the aqueous system hydra-
zine hydrate MOH at the MOH : S ratio of 4 : 3.
Dithiols IIIa and IIIb are colorless liquids. Their
S8 + 8MOH + 2N2H4 H2O
IR spectra contain medium-intensity bands corre-
1
sponding to the S H vibrations (2556 and 2545 cm ,
2M2S + 2M2S2 + 2N2 + 9H2O,
M2S1.5
(4)
respectively). The other bands are assigned in the
Experimental.
Dithiolate anions IVa formed by reduction of IIa
were alkylated with ethyl bromide, and products VIa
were isolated and characterized.
ClCH2CH2Cl + M2S1.5
IIc
(.5)
2MCl
The molecular weight of the resulting polymer IIc
is 4200.
IVa + C2H5Br
EtSCH2CH2OCH2CH2SEt.
(8)
Polymers IIa and IIb were reduced in the system
hydrazine hydrate alkali to thiolates IVa and IVb,
with the aim of subsequent preparation of the corre-
sponding thiols IIIa and IIIb and their derivatives.
VIa
Dithiol IIIb is also formed by reduction of poly-
mer IIc obtained by scheme (5) from dichloroethane
(yield 37%). 1,2-Ethanedithiol is formed simultane-
ously in approximately the same yield. At the same
time, reduction of the polymer prepared by scheme (2)
from yperite yields only traces (<1%) of 1,2-ethane-
dithiol.
2IIa, IIb + 4nMOH + nN2H4 H2O
2nMSCH2CH2YCH2CH2SM + nN2 + 5H2O.
IVa, IVb
(6)
Mild acidification of dithiolates IVa and IVb
formed by scheme (6) yielded dithiols IIIa and IIIb:
Formation of dithiol IIIb from the polymer pre-
pared by schemes (4) (7) from dichloroethane sug-
gests regular alternation of di- and monosulfide units
in IIc (see below):
IVa, IVb + 2H+
HSCH2CH2YCH2CH2SH.
(7)
2M+
IIIa, IIIb
S SCH2CH2S SCH2CH2SCH2CH2S SCH2CH2S SCH2CH2SCH2CH2S S
Ethanedithiol Dithiol IIIb Ethanedithiol Dithiol IIIb etc.
Decrease of the MOH : S ratio in reaction (4) to
1 : 1 and 1 : 1.5 favors generation of M2S2 and M2S3
and formation of polymers based on dichloroethane
[scheme (5)] with disulfide and trisulfide units. Sub-
sequent reduction of these polymers leads to sharply
increased (to 75%) yield of ethanedithiol [1] and to
decreased yield of dithiol IIIb (5% or traces).
does not exceed 33%, with dithiol IIIb formed only
in trace amounts.
We have shown previously [7] that in reactions
with chalcogenide anions Y2n (Y = S, Se, Te)
in hydrazine hydrate organyl chlorides are more
reactive than the corresponding organyl bromides
and even iodides. Therefore, different reactivity of
1,2-dichloroethane and 1,2-dibromoethane in thiyla-
tion in basic reducing media is due to the fact that
dichloroethane reacts equally fast with the anions
S2 , S22 , etc., whereas dibromoethane, probably, first
The polymer IIc prepared by reaction (5) from
dibromoethane is a viscous rubbery product with the
molecular weight of 3500. Its reduction by reactions
(6) and (7) mainly yields 1,2-ethanedithiol; its yield
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002

242
KORCHEVIN et al.
selectively reacts with di- and polysulfide anions
to form a polymer with di- and trisulfide units. Af-
ter exhaustion of polysulfide anions, further chain
propagation occurs at the expense of S2 anions,
and the structure of the resulting polymer will be as
follows:
SCH2CH2SCH2CH2S SCH2CH2S SCH2CH2S SCH2CH2SCH2CH2S
Ethanedithiol Ethanedithiol
Reduction of such macromolecular chain yields no
dithiol IIIb.
then cooled, and the resulting polymer was extracted
with chloroform. The organic layer was dried over
CaCl2, the solvent was removed in a vacuum, and the
residue was dried. Yield of IIa 62%. IR spectrum, ,
Thus, we have developed a simple route to such
dithiols as bis(2-mercaptoethyl) ether IIIa and bis(2-
mercaptoethyl) sulfide IIIb, based on simple commer-
cially available chemicals: elemental sulfur, alkali,
ether Ia, and sulfide Ib. Thiylation with elemental
sulfur of Ia or Ib in the aqueous system hydrazine
hydrate alkali yields the corresponding polysulfide
polymers, thiokols. Their reduction with the system
hydrazine hydrate alkali, followed by acidification of
the resulting thiolate anions, yields the corresponding
dithiols IIIa and IIIb. Dithiol IIIb can also be pre-
pared from thiokol IIc synthesized from dichloroeth-
ane and a sulfur solution at MOH : S 2 : 1.5.
1
cm : 2930, 2905, 2890, 2850 [ (C H)]; 1465, 1450,
1405, 1350 [ (CH2)]; 1280, 1100 [ (C O)]; 750
1
(C S); 470 (S S). For the H NMR spectrum, see
text. Found, %: C 34.61; H 5.88; S 48.33: Cl 4.02.
Calculated for the formula of IIa, %: C 35.29; H
5.88; S 47.06.
With 1 ml of hydrazine hydrate and equal other
conditions, the yield of IIa was 67%. Found, %:
Cl 8.62; S 41.18. C24H8Cl2O6S10. Calculated, %:
Cl 8.63; S 38.88.
Polymer IIb. A sulfur solution was prepared as
described above, and 7.8 g of Ib was added. The
mixture was kept for 2 h at 90 100 C. After cooling,
the polymer (white powder) was filtered off, washed
with water and ethanol, and dried. Yield of IIb 76%;
mp 90 100 C (with decomposition). IR spectrum,
EXPERIMENTAL
The IR spectra were recorded on an IF-525 Sample
Scant-250 spectrometer (thin films for liquids and
KBr pellets for solids).
The 1H NMR spectra were recorded on a Jeol
FX-90Q spectrometer (90 MHz) from 15 20% solu-
tions in CDCl3 or CCl3F.
1
, cm : 2930, 2905, 2890, 2850 [ (C H)]; 1465,
1450, 1405, 1350 [ (CH2)]; 810, 750 (C S); 471
(S S). Found, %: S 62.57: Cl 1.59. Calculated for
polymer IIb, %: S 63.16.
The GC MS analysis was performed with a GC
MS-5972 AHP device (50 m 0.2 mm 0.5 m cap-
illary column, PONA, carrier gas He, linear heating
Polymer IIc. a. A sulfur solution was prepared
from 4 g of NaOH, 30 ml of water, 5 ml of hydrazine
hydrate, and 2.4 g of sulfur, and 4.95 g of dichloro-
ethane was added in portions. The mixture was stirred
for 1 h at 90 C; after cooling, polymer IIc was filtered
off. Yield 83%; mp 95 100 C (with decomposition).
Found, %: S 61.06: Cl 1.62. Calculated for IIc, %:
S 63.16.
1
rate 12 deg min ).
The reaction progress was monitored and the prod-
uct purity checked with an LKhM-80MD chromato-
graph (2000 3-mm column, stationary phase 5%
Silicone XE-60 on Chromaton N-AW-HMDS, carrier
1
gas He, linear heating rate 12 deg min ).
b. Under similar conditions but at the molar ratio
NaOH : S 2 : 3, a rubbery polymer was obtained in
98% yield. Found, %: S 75.38: Cl 1.96. Calculated
for [SCH2CH2SS]n, %: S 77.42. M 3600.
Polymer IIa. A three-necked flask equipped with
a stirrer, a reflux condenser, a thermometer, and a
unit for loading reactants was charged with 4 g of
NaOH (or 5.6 g of KOH), 30 ml of water, and 5 ml
of hydrazine hydrate, and 3.2 g of sulfur was added
in portions with stirring. After the added sulfur dis-
solved, the mixture was stirred for 1 h at 90 C and
then cooled, and 7.15 g of Ia was added in portions at
20 25 C. The mixture was heated for 1 h at 80 C and
c. A sulfur solution was prepared under similar
conditions but at the ratio KOH : S 4 : 3, and 9.36 g
of 1,2-dibromoethane was added. The white rubbery
polymer was filtered off, washed with water and eth-
anol, and dried. Yield 62%. Found, %: S 64.51: Br
4.54. Calculated for IIc, %: S 63.16.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002

REACTIONS OF BIELECTROPHILES (ClCH2CH2)2Y WITH SULFUR IN BASIC REDUCING SYSTEMS 243
3-Oxapentane-1,5-dithiol IIIa. A 2.4-g portion of
NaOH was dissolved in 20 g of hydrazine hydrate,
and 3.5 g of thiokol IIa was added. The mixture was
stirred for 3 h at 80 90 C. After cooling, the mixture
was poured under argon onto ice (200 g) containing
45 ml of concentrated HCl. Dithiol IIIa was extracted
with ether, the extract was dried over MgSO4, the
solvent was removed in a vacuum, and the residue
was vacuum-distilled. The fraction with bp 80 81 C
(10 mm Hg) was practically pure dithiol IIIa. Yield
(SCH2), 3.62 t (OCH2). Mass spectrum, m/z (Irel, %):
165 (80) [M C2H5]+, 133 (15) [M SC2H5]+, 89
(100) [M C2H5SCH2CH2]+; 88 (90) [ CH2CH2S
CH2CH2 ]+, 75 (40) [C2H5SCH2]+, 61 (75) [C2H5S]+.
ACKNOWLEDGMENTS
The study was financially supported by the Russian
Foundation for Basic Research (project no. 00-03-
32810a).
1
25%. IR spectrum, , cm : 2936, 2914, 2886, 2854
[ (C H)]; 2557 [ (S H)]; 1454, 1417, 1357 [ (CH2)];
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1
1103 [ (C O)]; 760 (C S). H NMR spectrum,
,
ppm: 1.60 t (SH), 2.69 m (S CH2), 3.60 t (O CH2).
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isolation of IIIa; bp 40 C (10 mm Hg) [8]. The IR
spectrum contains the bands (CH2) and (CH2).
1H NMR spectrum, , ppm: 2.65 t (SCH2), 3.65 t
(OCH2). Mass spectrum, m/z (Irel, %): 104 (90) [M+],
74 (30) [M CH2O]+, 61 (70) [M CH2CHO]+; 46
(95) [CH2S]+; 27 (100) [CH2CH]+.
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3-Thiapentane-1,5-dithiol IIIb was prepared simi-
larly from IIb. Yield 34%; bp 115 C (5 mm Hg) [9].
1
IR spectrum, cm : 2934, 2918, 2846 [ (C H)], 2545
1
[ (S H)], 1426 [ (CH2)]; 765 (C S). H NMR spec-
trum, , ppm: 1.72 t (SH), 2.76 m (S CH2).
6-Oxa-3,9-dithiaundecane VIa. A 2.4-g portion
of NaOH was dissolved in 20 g of hydrazine hydrate,
and 4 g of thiokol IIa was added. After dissolution of
the thiokol, 6.54 g of ethyl bromide was added in
portions. The mixture was stirred for 1 h at 70 C.
The organic products were extracted with ether, the
extract was washed with water and dried over CaCl2,
the solvent was distilled off, and the residue was vac-
uum-distilled. Yield of VIa 1.45 g (30%); bp 100 C
(3 mm Hg). Found, %: C 50.02; H 9.24; S 33.07.
C8H18OS2. Calculated, %: C 49.48; H 9.28; S 32.99.
1H NMR spectrum, , ppm: 1.25 t (CH3), 2.62 m
9. Simoos, M., Qimica, 1942, no. 1, p. 475; Chem. Abstr.,
1946, vol. 40, no. 2798.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002