Process for the preparation of aromatic sulfur compounds

Details Process for the preparation of aromatic sulfur compounds Process for the preparation of aromatic sulfur compounds

2000-05-04

2002-04-23

Vollano, Jean F. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Sulfur containing

C568S029000, C568S025000, C568S061000, C568S067000

Reexamination Certificate

active

06376716

ABSTRACT:

Process for the preparation of aromatic sulfur compounds
1. Technical Field
This invention relates to the preparation of aromatic thiols from aromatic thioethers, and also, relates to the preparation of aromatic disulfides via said aromatic thiols. The present invention further relates to the preparation of aromatic thiols via the above-mentioned aromatic thioethers obtained from aromatic halogeno-compounds, and the preparation of aromatic disulfides via said aromatic thiols.
2. Background Art
Aromatic thiols represented by the general formula (Ia):
wherein Y represents chloro, bromo, iodo, nitro, nitrile, sulfone, sulfamoyl and hydrocarbylsulfonyl groups, each of which may be the same or different from each other; m is an integer of 1 to 6, n is 0 or an integer of 1 to 5, provided that m+n is 6 or less,
and aromatic disulfides represented by the general formula (IIIa):
wherein Y and n have the same meanings as defined above, have been used as an intermediates of medicines, agricultural chemicals, electronic materials, etc.
Some processes for the aromatic monothiols, aromatic dithiols or aromatic disulfides having such substituents have been proposed.
For example, in Kogyo Kagaku Zasshi, vol. 70, No. 8, pp. 114-118 (1967), the preparation of halogenated aromatic thiol which comprises reacting polychlorinated benzene with sodium hydrogen sulfate in liquid ammonia with autoclave to substitute one of the chlorine atom to a mercapto group is described. According to this method, halogenated aromatic thiol can be obtained in a high yield from polychloro benzene having 4 to 6 chlorine atoms, but the yield for dichlorothiophenol from trichlorobenzene is only 17 to 20% and also there are many problems and complexities to handle liquid ammonia and an industrial limitation due to the high pressure reaction with autoclave.
In Japanese Patent Publication No. 26100/1979, there is disclosed the preparation of halogenated aromatic thiol which comprises the reaction of halogenated aminoaromatic compound with sodium nitrite and conc. hydrochloric acid to form diazonium compound which reacts under reflux with potassium O-ethyldithiocarbonate and sodium hydroxide. This method is not preferred since it is not only complex but also dangerous to handle the diazonium salt.
In Japanese Provisional Patent Publication No. 156257/1981, there is disclosed the preparation of 3,5-dichlorothiophenols which comprises reacting 1,3,5-tri-chlorobenzene or 1-bromo-3,5-dichlorobenzene with alkali metal sulfide in a solvent such as diethylene glycol. This process gives objective compound with a relatively easy operation but the yield is low and many byproducts are formed so that the purification is difficult.
In Zhur. Org. Khim. vol. 11, p. 1132 (1975), there is disclosed the preparation of aromatic thiol by reacting halogenated aryl compound with hydrogen sulfide in the presence of thorium oxide, but the process requires high temperature (550° C. or higher) and the yield is not good.
In Japanese Provisional Patent Publication No. 48564/1990, there is disclosed the preparation of thiophenol by the introduction into a benzene ring having no nitro group of a diaryl sulfide, by the electrophilic substitution of the group such as halogeno, nitro group, etc. on the benzene ring of the diaryl sulfide having a nitro group at one of the benzene rings and then, the resulting compound is subjected to the exchange reaction with thiophenol in the presence of a basic substance such as sodium hydroxide whereby thiophenol the nucleus of which is substituted by said substituent can be obtained. However, this process is complex and it is not suitable when a lot of substituents is to be introduced into the benzene ring of the thiophenol.
In Japanese Provisional Patent Publication No. 72749/1986, there is disclosed the preparation of o-halothiophenols by the reaction of N,N-dialkylcarbamoyl halide with an o-halophenol to synthesize O-o-halophenyl-N,N-dialkyl-carbamates, and the rearrangement reaction of S-o-halophenyl-N,N-dialkylcarbamate by heating, and hydrolysis of the resulting compound. However, this process is difficult of operation because of a complex multi-step reaction and passing through unstable carbamoyl halide. Also, the rearrangement reaction is carried out at high temperature whereby side reactions occur, and the process is particularly disadvantageous for the introduction of substituent except halogen.
There are disclosed the preparation of corresponding halogenated thiophenol by the reduction of 4-halobenzene sulfinic acid (in Japanese Provisional Patent Publication No. 295968/1990), 4-halobenzene sulfonyl chloride (in Japanese Provisional Patent Publication No. 181455/1991), and halobenzene sulfenyl halide (in Japanese Provisional Patent Publication No. 186418/1993), respectively, by the use of metal powder such as zinc powder with a mineral acid. However, this reduction is carried out in the presence of a mineral acid so that a specific apparatus is required.
In Japanese Provisional Patent Publication No. 140086/1993, there is disclosed the preparation of halothiophenol by the reaction of monohalobenzene with sulfur monochloride using a catalyst such as zinc chloride, and the reduction of the resulting product by a reducing agent such as zinc, etc. This process also consists of the reduction as mentioned above so that the same problems are involved.
In Japanese Provisional Patent Publication No. 182463/1992, there is disclosed a process for the preparation of halothiophenol by the reaction of poly-halobenzene with sulfide such as sodium hydrogen sulfide, sodium sulfide, potassium sulfide, etc. In these processes, the rate of the reaction is slow so that the formed aromatic thiol reacts with the halogenated benzene to give aromatic sulfide whereby the yield is low.
In Japanese Provisional Patent Publication No. 198162/1992, there is disclosed the preparation of halogenoaromatic thiol by the reaction of poly-halogenobenzene with thioglycolate. In Japanese Provisional Patent Publication No. 178816/1993, there is disclosed the preparation of halogenoaromatic thiol by the reaction of halogenated phenyl thioglycollic acid with sulfide such as sodium hydrogen sulfide or aromatic thiol with a base. But, highly pure aromatic thiol cannot be obtained with good yield by this process.
In Japanese Provisional Patent Publication No. 143533/1996, there is disclosed the preparation of halogenoaromatic thiol by the chlorination of the methyl group bound to the sulfur atom of thioanisol by chlorine gas and then the hydrolysis of the resulting halogenothioanisol. Moreover, in Japanese Provisional Patent Publication No. 143532/1996, there is disclosed that hydrolysis of the above-mentioned halogenated thioanisol is carried out in the presence of a mineral acid, and halogenated aromatic disulfide can be obtained by the oxidative dimerization of the halogenoaromatic thiol obtained by said hydrolysis with an oxidizing agent such as hydrogen peroxide, etc. However, in this process, methyl mercaptane which is volatile and stinks is used, and complex step of introducing a chlorine gas to chlorinate a methyl group is required. Incidentally, it has not yet been known about the reaction to prepare aromatic thiol from aromatic thioether in the presence of a Lewis acid by eliminating a hydrocarbyl group.
The object of this invention is to provide the preparation of highly pure aromatic thiols and disulfides with good yields from the substituted aromatic thioethers in benzene. Another object is to provide the preparation of highly pure aromatic thiols and disulfides having a substituent(s) from aromatic halogeno compounds by simple and easy operation with good yield.
The present inventors have studied to solve the above-mentioned problems, and as a result, they have found that a hydrocarbyl group of aromatic thioethers having specific hydrocarbyl group can be easily eliminated in the presence of a Lewis acid or a protonic acid, and the aromatic halogeno compounds are allowed to react with specific hydrocarbyl-mercaptide alkali metal salt

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