ISSN 1070-4280, Russian Journal of Organic Chemistry, 2018, Vol. 54, No. 12, pp. 1794–1797. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © A.V. Mashkina, L.N. Khairulina, 2018, published in Zhurnal Organicheskoi Khimii, 2018, Vol. 54, No. 12, pp. 1780–1783.
Catalytic Synthesis of Methylthiophenes
A. V. Mashkinaa* and L. N. Khairulinaa
a Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences,
pr. Akad. Lavrent’eva 5, Novosibirsk, 630090 Russia
*e-mail: amash@catalysis.ru
Received January 12, 2018; revised October 10, 2018; accepted October 19, 2018
Abstract—The gas-phase reaction of dimethyl disulfide with thiophene over Co/HZSM-5 catalyst in a helium
medium under atmospheric pressure at 250–350°C gave a mixture of mono-, di-, tri-, and tetramethylthio-
phenes with an overall selectivity of 94–96%.
DOI: 10.1134/S1070428018120096
Methylthiophenes are used as starting materials for
the preparation of fuel additives, antioxidants, rubber
vulcanization accelerators, monomers, medicines,
herbicides, and insectofungicides. Methylthiophene
has found application as an animal hair growth stimu-
lator, hair care agent, and weight-gain supplement.
Methylthiophenes can be synthesized by dehydro-
cyclization of diene hydrocarbons with hydrogen
sulfide, from 1,4-dicarbonyl compounds and phos-
phorus heptasulfide, from furans and hydrogen sulfide
[1–4]. Accessibility of starting materials is an impor-
tant factor for the choice of a method for the prepara-
tion of methylthiophenes. Accessible and cheap start-
ing compounds are lower dialkyl disulfides [mostly di-
methyl disulfide (1)] that are isolated in large amounts
from oxidative desulfurization products of petroleum,
natural gas, and gas condensate [5].
tion of hydrocarbons, hydrogen sulfide, and high-
boiling compounds which were not identified.
Pure dimethyl disulfide (1) (initial concentration
~3.5 vol %) over Co/HZSM-5 at 200–350°C decom-
posed to produce methanethiol, dimethyl sulfide,
hydrogen sulfide, dimethyl trisulfide, ethylene, and
“coke” (Scheme 1). At 200°C, the transformation of
dimethyl disulfide occurred even in a short contact
time; subsequently, the conversion of 1 and the yields
of dimethyl sulfide and hydrogen sulfide increased; the
yield of methanethiol increased up to a certain limiting
value and then decreased, whereas the yield of
dimethyl trisulfide decreased as the contact time in-
creased (Table 1). Raising the temperature accelerated
the reaction. Presumably, increased yield of dimethyl
sulfide at elevated temperature and longer contact time
is related to preferential formation of methyl fragments
on the catalyst surface. As shown in [7], disulfide 1 in
the presence of solid acid catalysts decomposed to
methanethiol which was then converted to dimethyl
sulfide and hydrogen sulfide; in addition, partial
cracking of initial disulfide 1, methanethiol, and di-
methyl sulfide occurred.
In this work we studied the formation of methyl-
thiophenes in the reaction of dimethyl disulfide with
thiophene in the presence of cobalt-containing
HZSM-5 high-silica zeolite. This catalyst possesses
active surface protonic and Lewis acid sites, as well as
moderate-strength basic sites [6], which activate the
reactants and favor the reaction.
Dimethyl disulfide (1) in the presence of thiophene
decomposed in the same manner as in the absence of
it, but at a lower rate (Table 1). Thiophene reacted with
disulfide 1 at 160–200°C to give mainly sulfonyl-
The reaction of thiophene with dimethyl disulfide
(1) was carried out at a reactant molar ratio of 1:(4–5)
over Co/HZSM-5 catalyst in the gas phase (helium,
atmospheric pressure) at different temperatures and
contact times. Preliminarily, the behavior of pure thio-
phene (initial concentration ~0.8 vol %) was studied
under these conditions. Almost no decomposition of
thiophene was observed at 200–250°C. At 300°C, the
conversion of thiophene was 3–10% with the forma-
Scheme 1.
2MeSH
Me2S + H2S
Me2S2
1
H2S + H2C=CH2 + Me2S3 + “coke”
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