Nucleophilic Cleavage of the Ether Bond of Chlorex in the Chalcogenation with Diphenyl Dichalcogenides in the System Hydrazine Hydrate–KOH

Article abstract of DOI:10.1134/S1070363220090273

Abstract: The synthesis of unsymmetrical pincer ligands by reactions of diphenyl disulfide and diphenyl diselenide with bis(2-chloroethyl) ether in the system hydrazine hydrate–KOH was accompanied by the formation of 1,2-bis(phenylsulfanyl)ethane, 1,2-bis(phenylselanyl)ethane, and 1-(phenylselanyl)-2-(phenylsulfanyl)ethane as by-products with an overall yield of 23% as a result of nucleophilic cleavage of the C–O–C bond in the initial ether.

Full text of DOI:10.1134/S1070363220090273

ISSN 1070-3632, Russian Journal of General Chemistry, 2020, Vol. 90, No. 9, pp. 1760–1762. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Obshchei Khimii, 2020, Vol. 90, No. 9, pp. 1469–1472.
SHORT
COMMUNICATIONS
Nucleophilic Cleavage of the Ether Bond of Chlorex
in the Chalcogenation with Diphenyl Dichalcogenides
in the System Hydrazine Hydrate–KOH
V. A. Grabelʼnykha,*, I. N. Bogdanovaa, V. S. Nikonovaa, N. G. Sosnovskayab, N. V. Istominab,
N. V. Russavskayaa, A. I. Albanova, I. B. Rozentsveiga, and N. A. Korchevina,b
a Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, 664033 Russia
b Angarsk State Technical University, Angarsk, 665835 Russia
*e-mail: venk@irioch.irk.ru
Received June 1, 2020; revised June 1, 2020; accepted June 12, 2020
Abstract—The synthesis of unsymmetrical pincer ligands by reactions of diphenyl disulfide and diphenyl di-
selenide with bis(2-chloroethyl) ether in the system hydrazine hydrate–KOH was accompanied by the formation
of 1,2-bis(phenylsulfanyl)ethane, 1,2-bis(phenylselanyl)ethane, and 1-(phenylselanyl)-2-(phenylsulfanyl)ethane as
by-products with an overall yield of 23% as a result of nucleophilic cleavage of the C–O–C bond in the initial ether.
Keywords: multidentate ligands, chlorex, chalcogenation, diphenyl disulfide, diphenyl diselenide
DOI: 10.1134/S1070363220090273
Dichalcogenide metal chelates represent now an
important field of coordination [1, 2], catalytic [3–6],
analytical [7–9], and structural chemistry. In addition,
they are potential precursors to nanostructured transition
metal chalcogenide films that are promising materials for
electronics [10].
and subsequent reaction of the resulting chalcogenolates
RY– with chlorex; in this case, the yields of the target
compounds were 60–68% (57–64% from Ph2Y2). The
synthesis of ligands containing both oxygen atom and
two different chalcogen atoms was described in [12].
However, only methyl derivatives were obtained in
58–72% yield [12], and the reaction was accompanied
by the formation of compounds with similar chalcogen
atoms. These syntheses were carried out at 60–65°C
(2.5 h). When the temperature was lowered to 40–45°C
(1 h), products of replacement of only one chlorine
atom in chlorex were identified in the reaction mixture
(yield 14–15%). No compounds that could be formed as
a result of cleavage of the C–O–C bond in chlorex were
detected. This bond in ethers, including chlorex [14], is
fairly strong. Cleavage of ethers with hydrogen iodide is
well known [15]; however, ethers are stable under alkaline
conditions even in the presence of strong nucleophiles.
Bis(2-chloroethyl) ether (1, chlorex) is a very
important reagent for the synthesis of pincer ligands
containing several donor centers for coordination [11, 12].
We previously synthesized chromium(III) complexes with
chalcogen-containing ligands derived from chlorex [13],
and these complexes were used in structural studies and
as components of catalytic systems for oligomerization
of olefins.
Two approaches have been developed for the synthesis
of multidentate ligands based on chlorex [11, 12]. The
first approach is applicable to the preparation of aliphatic
chalcogenide derivatives. It involves preliminary
synthesis of oligomeric dichalcogenides containing a
3-oxapentamethylene fragment and their reductive at the
chalcogen–chalcogen bond, followed by alkylation. The
target products were thus obtained in 56–74% yield. The
second approach is based on the reductive cleavage of
organic dichalcogenides R2Y2 (R = Alk, Ar; Y = S, Se)
While developing our studies aimed at synthesizing
multidentate ligands with two different chalcogen
atoms, an equimolar mixture of diphenyl disulfide and
diphenyl diselenide was reacted with chlorex (1) under
the conditions described in [11, 12] (65–70°C, 2.5 h).
Surprisingly, apart from expected products 2a–2c
1760

NUCLEOPHILIC CLEAVAGE OF THE ETHER BOND OF CHLOREX
1761
Scheme 1.
Scheme 2.
(overall yield 38% based on total Ph2Y2), we isolated
bis(phenylchalcogenyl)ethanes 3a–3c (overall yield 23%)
which were formed as a result of cleavage of the ether
bond in 1. The reductive cleavage of Ph2Y2 (Y=S, Se) in
the system hydrazine hydrate–KOH was carried out as
described in [11] (Scheme 1). Each dichalcogenide was
reduced separately, solutions of 4a and 4b were then
combined, and chlorex was added to the resulting mixture.
hydrate–potassium hydroxide gives not only products of
substitution of chlorine atoms in chlorex but also products
of ether bond cleavage, which opens a synthetic route
to difficultly obtainable bis(phenylchalcogenyl)ethanes.
Reaction of diphenyl disulfide and diphenyl
diselenide with chlorex (1) in the system hydrazine
hydrate–KOH. Diphenyl disulfide, 5.46 g (0.025 mol),
was added in portions to a solution of 6.72 g (0.12 mol)
of KOH in 30 mL of hydrazine hydrate, and the mixture
was stirred for 1.5 h at 80–85°C. Likewise, a solution of
7.8 g (0.025 mol) of diphenyl diselenide was prepared in
a separate vessel. The obtained solutions were cooled to
25°C and mixed together, 5.9 mL (0.05 mol) of chlorex
(1) was added to the mixture, and the mixture was stirred
for 1.5 h at 65–70°C. After cooling, the organic layer
(6.65 g) was separated, and the aqueous hydrazine layer
was extracted with diethyl ether (2×50 mL). The extract
was dried, and the solvent was distilled off to leave 0.95 g
of the residue. GC/MS analysis showed the presence
of compounds 2a–2c and 3a–3c (~85%) and volatile
impurities (15%) which were not identified. By vacuum
distillation (2 mm Hg) we succeeded in separating only
volatile components of the residue and obtaining fractions
enriched in either 3a–3c or 2a–2c.
The formation of 2a–2c and 3a–3c can be illustrated
by Scheme 2.According to the 1H NMR data, the 2a : 2b :
2c molar ratio was 1.0 : 3.0 : 2.0, and the ratio 3a : 3b :
3c was 1.0 : 2.8 : 1.8, which indicates higher reactivity of
PhSe– ions in both substitution of chlorine in 1 and ether
bond cleavage. Taking into account that separate reactions
of 4a and 4b with chlorex under similar temperature
conditions did not produce compounds 3a and 3c even
when the reaction time was prolonged to 5 h (only traces
of 3a or 3c were detected), cleavage of the ether bond
according to Scheme 2 is likely to require simultaneous
action of PhS– and PhSe– ions. The nature and mechanism
of the synergistic effect of these anions on the ether bond
cleavage is the subject of a separate study.
Compounds 2a and 2c were described previously
[11]. Unsymmetrical bischalcogenide 2b was previously
unknown and was characterized by a set of spectral
methods (1H, 13C, and 77Se NMR, IR, and GC/MS) in
a mixture with 2a and 2c. Signals in the NMR spectra
were assigned using heteronuclear shift correlation
experiments (HMBC 77Se and HSQC 13C) [16].
1
The H, 13C, and 77Se NMR spectra of 2a and 2c
were fully identical to those reported in [11]. Their mass
spectral data are given for the first time: m/z 290 (2a),
386 (80Se, 2c).
Phenyl{2-[2-(phenylselanyl)ethoxy]ethyl}sulfane
(2b) was characterized in a mixture with other products.
1H NMR spectrum (CDCl3), δ, ppm: 2.95 m (2H, CH2Se),
2.99 m (2H, CH2S), 3.53 m and 3.62 m (4H, CH2O),
7.21–7.55 m (10H, Ph). 13C NMR spectrum (CDCl3), δC,
ppm: 26.62 (CH2Se), 33.08 (CH2S), 69.36, 70.38 (CH2O),
126.12–135.86 (Ph). 77Se NMR spectrum (CDCl3): δSe
270.25 ppm. Mass spectrum: m/z 338 (80Se).
Bischalcogendes 3a–3c were synthesized previously
via multistep procedures or from 1,2-dibromoethane
[6, 17]. Their 1H and 13C NMR spectra were given in [6].
It should be noted that no compounds 3a–3c were formed
when 1,2-dichloroethane was directly reacted with 4a and
4b in N2H4·H2O–KOH.
Thus, the reaction of chlorex with a mixture of diphenyl
disulfide and diphenyl diselenide in the system hydrazine
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 90 No. 9 2020

1762
GRABELʼNYKH et al.
Int. Ed. 2013, vol. 52, no. 9, p. 2538.
1,1′-(Ethane-1,2-diyldisulfanediyl)dibenzene (3a).
Hereinafter, chemical shifts reported in [6] are given
in parentheses. H NMR spectrum (CDCl3), δ, ppm:
3.00 s (3.08 s) (4H, CH2S), 7.21–7.55 m (7.22–7.65 m)
(10H, Ph). 13C NMR spectrum (CDCl3), δC, ppm: 33.26
(33.34) (CH2S), 126.12–135.86 (126.0–132.9) (Ph). Mass
spectrum: m/z: 246.
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Phenyl-[2-(phenylselanyl)ethyl]sulfane (3b). H
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(2H, CH2Se), 3.00 m (3.12–3.19 m) (2H, CH2S), 7.21–
7.55 m (7.16–7.61 m) (10H, Ph). 13C NMR spectrum
(CDCl3), δC, ppm: 26.40 (26.5) (CH2Se), 33.06 (34.2)
(CH2S), 126.12–135.86 (126.5–135.1) (Ph). 77Se NMR
spectrum (CDCl3): δSe 323.61 ppm. Mass spectrum: m/z
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1,1′-(Ethane-1,2-diyldiselanediyl)dibenzene (3c).
1H NMR spectrum (CDCl3), δ, ppm: 3.04 s (3.16 s) (4H,
CH2Se), 7.21–7.55 m (7.26–7.65 m) (Ph). 13C NMR
spectrum (CDCl3), δC, ppm: 27.16 (27.2) (CH2Se),
126.12–135.86 (127.2–133.1) (Ph). NMR spectrum 77Se
(CDCl3): δSe 341.91 ppm: Mass spectrum: m/z 342 (80Se).
1
The H, 13C, and 77Se NMR spectra were recorded
on a Bruker DPX-400 spectrometer at 400.13, 100.62,
and 76.31 MHz, respectively, using tetramethylsilane
(1H, 13C) and dimethyl diselenide (77Se) as internal
standards. The mass spectra were run on a Shimadzu
GCMS-QP5050A instrument (SPB-5 capillary column,
60 m×0.25 mm; quadrupole mass analyzer, electron
impact, 70 eV; ion source temperature 190°C; a.m.u.
range 34–650).
ACKNOWLEDGMENTS
This study was performed using the facilities of the Baikal
Joint Analytical Center, Siberian Branch, Russian Academy
of Sciences.
14. Pokonova, Yu.V., Khimiya i tekhnologiya galogenefirov
(Chemistry and Technology of Halo Ethers), Leningrad:
Leningr. Gos. Univ., 1982.
CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
15. Traven’, V.F., Organicheskaya khimiya (Organic Che-
mistry), Moscow: Akademkniga, 2006.
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