JPS6151581B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing parahalogenothiophenol.
A parahalogenothiophenol characterized by subjecting 4,4'-dihalogenodiphenyl sulfide or/and 4-halogenodiphenyl sulfide and hydrogen sulfide to a gas phase reaction in the absence or presence of a catalyst. This relates to a manufacturing method. Parahalogenothiophenols are valuable compounds as intermediates for pesticides, pharmaceuticals, and dyes. Conventionally, various methods have been known for producing parahalogenothiophenol. US Pat. No. 3,331,205 and US Pat. No. 3,474,139 describe a method of chlorinating thiophenol to produce parachlorosulfenyl chloride, and then reducing this to produce chlorothiophenol. However, in this method, a considerable amount of the isomer orthochlorothiophenol is produced as a by-product, and the boiling points of the two are similar, making purification extremely troublesome. Therefore, it has the disadvantage that a product of high purity cannot be obtained and the yield is low. Furthermore, in US Pat. No. 3,296,308, phenylmercaptoacetic acid is produced by reacting monochloroacetic acid with thiophenol, which is chlorinated to produce parachlorophenylmercaptoacetic acid, and then parachlorophenylmercaptoacetic acid is produced through the decomposition of sulfide. A method for producing phenol is described. Although this method has the advantage of selectively obtaining parachlorothiophenol over the former method, it has the disadvantage that the process is particularly long, and it cannot be said to be an industrially advantageous method. Additionally, US Pat. No. 3,326,981 describes a method for reducing parachlorobenzenesulfonyl chloride with zinc, and Chemische Berichte., 99, 376 ('66) describes a method for reducing parachlorobenzenesulfonyl chloride with phosphorus. . However, both methods have drawbacks in that the reducing agent is expensive and a large amount of waste water containing zinc or phosphorus, which causes pollution, is produced. Also, Zhurnal Organicheskoi Khimii.
1975, 11(5), 1132, by reacting paradichlorobenzene and hydrogen sulfide at a high temperature of 580℃,
A method for obtaining parachlorothiophenol is described. However, the yield of parachlorothiophenol is low and a large amount of by-products are produced. The present invention produces parahalogenothiophenols by reacting 4,4'-dihalogenodiphenyl sulfide or/and 4-halogenodiphenyl sulfide with hydrogen sulfide at elevated temperatures. However, in conventional literature,
It was thought that the halogen groups of halogenated aromatic compounds would be dehalogenated by the action of hydrogen sulfide or sodium hydrogen sulfide at high temperatures. For example, in US Pat. No. 3,415,889, thiophenol is obtained by heating paradichlorobenzene or 1,2,4-trichlorobenzene with sodium sulfide in an autoclave to 250-350°C. This is clearly paradichlorobenzene or 1,
This shows that the dehalogenation reaction of 2,4-trichlorobenzene is occurring. Also, Zhurnal Organicheskoi Khimii., 1975,
Since the reaction between paradichlorobenzene and hydrogen sulfide in 11(5) and 1132 requires a high temperature of 580°C, dehalogenation of paradichlorobenzene or the produced parachlorothiophenol occurs, and eventually parachlorothiophenol is formed. The yield is considered to be extremely low. Furthermore, Japanese Patent Publication No. 5531/1983 describes a method for producing thiophenol from diphenyl sulfide and hydrogen sulfide in a gas phase catalytic manner. However, nothing is described about the reaction between halogen-containing diphenyl sulfide and hydrogen sulfide, and the reaction of the present invention is not suggested in view of the above-mentioned dehalogenation relationship. The present inventors have conducted intensive research on the method for producing parahalogenothiophenol, but 4.
By causing a gas phase reaction of 4'-dihalogenodiphenyl sulfide or 4-halogenodiphenyl sulfide and hydrogen sulfide at elevated temperature,
4,4′-dihalogenodiphenyl sulfide or 4
-We have discovered that parahalogenothiophenol can be obtained in good yield by suppressing the dehalogenation of halogenodiphenyl sulfide, and have arrived at the present invention. The features of the present invention are that a product of high purity can be obtained, the yield is high, the process is simple, and it is a closed, pollution-free process. Therefore, it is economically advantageous. Furthermore, specifically, a high purity product can be obtained with no by-products other than a small amount of thiophenol, such as orthohalogenothiophenol, and unreacted 4,4'-dihalogenodiphenyl sulfide. , or by recycling 4-halogenodiphenyl sulfide, parahalogenothiophenol can be obtained in high yield, and by recycling unreacted hydrogen sulfide, it causes pollution. It has various features such as not producing any waste liquid. Embodiments of the present invention will be described below. Although this reaction can proceed satisfactorily without a catalyst, it can be carried out at a lower temperature using a catalyst. That is, in the case of no catalyst, a temperature of 400 to 550°C is usually appropriate, although it depends on other reaction conditions. In this case, the reaction hardly progresses below 400°C, and dehalogenation reaction occurs above 550°C, which increases the production of thiophenol and reduces the yield of parahalogenothiophenol. Further, when activated carbon, metal oxide, or metal sulfide is used, a temperature of 200 to 450°C is appropriate. For example, when activated carbon is used as a catalyst, the reaction temperature
Below 200°C, the reaction does not proceed, and above 450°C, a dehalogenation reaction occurs, increasing the production of thiophenol and reducing the yield of parahalogenothiophenol. In either case, it is preferable to lower the reaction temperature to increase the yield of parahalogenothiophenol per raw material, even if the rate of change of the raw material is sacrificed to some extent. The catalyst of the present invention includes activated carbon, metal oxide,
Metal sulfides, activated alumina, etc. can be used. There is no need to specifically explain activated carbon and activated alumina, but examples of metal oxides and metal sulfides include nickel oxide, cobalt oxide, molybdenum oxide, iron oxide, chromium oxide, nickel sulfide, cobalt sulfide, molybdenum sulfide, and sulfide. There are iron, etc., and it may be more effective to use two or more of these in combination than to use them alone. Moreover, these metal oxides or metal sulfides are rather generally used by being supported on porous materials such as diatomaceous earth, alumina, silica, silica-alumina, pumice, and activated carbon. The higher the molar ratio of hydrogen sulfide to 4,4'-dihalogenodiphenyl sulfide or 4-halogenodiphenylsulfide, the more 4,4'-dihalogenodiphenyl sulfide or 4-halogenodiphenyls The yield of parahalogenothiophenol relative to rufido is higher. However, increasing this molar ratio too much is rather uneconomical, and at least 4,4'-dihalogenodiphenyl sulfide or 4-halogenodiphenyl sulfide is sufficiently gasified at the reaction temperature. A molar ratio that maintains the same condition is required, and the molar ratio is preferably in the range of 1 to 50. In addition, when carrying out the present invention using a catalyst, the space velocity (the value obtained by dividing the raw material gas amount by the catalyst volume) is:
Although it varies depending on other reaction conditions, 30~
A range of 1000 [1/Hr] is preferable. Even when a catalyst is not used, the above range calculated using the space volume of the reaction tube in the predetermined temperature range is preferable. The raw materials 4,4'-dihalogenodiphenyl sulfide and 4-halogenodiphenyl sulfide can be obtained, for example, by halogenating diphenyl sulfide. When 4,4'-dihalogenodiphenyl sulfide is used as a raw material, stoichiometrically, 2 moles of halogenothiophenol can be obtained per 1 mole of the raw material. On the other hand, when 4-halogenodiphenyl sulfide is used as a raw material, 1 mole of halogenothiophenol and 1 mole of thiophenol are produced per mole of raw material. However, in all cases, the production of thiophenol and diphenyl sulfide, which seems to be due to a slight dehalogenation reaction, is observed. These thiophenol and diphenyl sulfide can be easily separated from parahalogenothiophenol by distillation. The by-produced thiophenol itself is a substance that has various uses, but it can be converted to diphenyl sulfide through a desulfurization reaction at high temperatures in the gas phase. Diphenyl sulfide can be converted back into 4,4'-dihalogenodiphenyl sulfide or 4-halogenodiphenyl sulfide by chlorination. In particular, 4,4' dihalogenodiphenyl sulfide is a substance with a high melting point that is solid at room temperature, and can also be supplied dissolved in a solvent that does not affect this reaction, such as benzene, toluene, xylene, chlorobenzene, etc. . In the reaction of the present invention, 4,4'-dihalogenodiphenyl sulfide or 4-halogenodiphenyl sulfide, or a solution thereof, such as a benzene solution, and hydrogen sulfide are heated to an elevated temperature by an appropriate method. This is carried out by preheating the mixture to a temperature and then introducing it into a reactor. If necessary, the inside of the reactor is filled with a porcelain ring or the like to improve gas dispersion, or the reactor is filled with the above-mentioned catalyst. The reaction can be carried out either at normal pressure or elevated pressure, and when a catalyst is used, it can be carried out in either a fixed bed or a fluidized bed. However, since the reaction heat of this reaction is not so large, there is little advantage in carrying out this reaction in a fluidized bed. The product gas obtained from the reactor is cooled and separated into gas and liquid. When the above-mentioned solvent is not used, unreacted raw materials may precipitate and block the cooler unless the temperature of the cooler is particularly adjusted. The reaction product condensed or solidified in the cooler is purified by a conventional method. For example, when the reaction product is distilled when a benzene solution of 4,4'-dichlorodiphenyl sulfide is used as a raw material, a small amount of thiophenol is distilled out under reduced pressure following the benzene solvent, and then a high purity of parachlorothiophenol is distilled out as a product. The bottom residue consists of 4,4'-dichlorodiphenyl sulfide containing a small amount of diphenyl sulfide and 4-chlordiphenyl sulfide, which is further distilled under reduced pressure to recover the raw material. can be done. On the other hand, hydrogen sulfide containing a small amount of hydrochloric acid gas can be recycled as is, or it can be washed with an aqueous solution of sodium hydrogen sulfide to remove the hydrochloric acid gas and used again as a raw material. The present invention will be explained in more detail with reference to Examples below, but these are not intended to limit the scope of the present invention. Example 1 25% by weight benzene solution of 4,4'-dichlorodiphenyl sulfide (mp 95°C) obtained by chlorination of diphenyl sulfide
36g/Hr and hydrogen sulfide 150c.c./min (molar ratio 11.5) in an inner diameter filled with a porcelain ring with an outer diameter of 5m/m.
It was supplied to a preheater consisting of a stainless steel pipe with a length of 40 m/m and a length of 200 m/m. The preheater was heated with an electric furnace to vaporize the raw material, and the temperature was adjusted to 400°C. The raw material gas leaving the preheater is heated to an outer diameter of 5 m/m and a height of
Inner diameter filled with 5m/m porcelain ring 200c.c.
It was introduced into a reactor consisting of a stainless steel pipe with a length of 40 m/m and a length of 500 m/m. The reactor was heated by a band heater,
The internal porcelain ring was maintained at 500°C. The reaction gas discharged from the reactor was cooled to about 20°C, and the reaction liquid was collected. When the reaction solution was analyzed by gas chromatography, the composition of the reaction solution excluding benzene was 16.0wt% parachlorothiophenol, 1.2wt% thiophenol, and 82.2wt% 4,4'-dichlorodiphenyl sulfide. %, diphenyl sulfide,
There was only a trace of 4-chlordiphenyl sulfide. When the reactor was maintained at 380°C, the composition was 0.1 wt% parachlorothiophenol, 0.1 wt% thiophenol, and 99.7 wt% 4,4'-dichlorodiphenyl sulfide. Example 2 25wt% of 4,4'-dichlorophenyl sulfide
solution of 36g/Hr and hydrogen sulfide 150c.c./min (mole ratio
11.5) was supplied to the same preheater as in Example 1, and the raw material was gasified and adjusted to 270°C. The raw material gas exiting the preheater was supplied to the same reactor as in Example 1. Inside the reactor, 200 c.c. of cylindrical activated carbon (manufactured by Takeda Pharmaceutical, Shirasagi Charcoal CX) of 4 m/mφ x 6 m/m was filled (space velocity 88 [1/Hv]), and the temperature of the catalyst layer was adjusted.
It was maintained at 300°C. After the gas at the outlet of the reactor was cooled to about 20°C and the flow reached a steady state, the reaction solution was analyzed. Nilsulfide
1.1wt%, 4,4'-dichlorophenyl sulfide
It was 70.9wt%. In addition, when the temperature of the reactor was maintained at 460℃, parachlorothiophenol 5.1wt%, thiophenol
46.5wt%, diphenyl sulfide 4.8wt%, 4-
Chlordiphenyl sulfide 1.2wt%, 4,4-
Dichlordiphenyl sulfide was 38.1wt%. Examples 3 to 11 Reactions were carried out using the same apparatus as in Example 2 with various raw materials, catalysts, and reaction conditions. Table 1 lists the results of gas chromatography analysis of the reaction solution. 【table】

Claims (1)

[Claims] 1. 4,4'-dihalogenodiphenyl sulfide or/and 4-halogenodiphenyl sulfide and hydrogen sulfide in a molar ratio of 1:10 to 30 and a temperature of 400 to 550.
A method for producing parahalogenothiophenol, characterized by maintaining the temperature at °C and reacting in the gas phase. 2 4,4′-dihalogenodiphenyl sulfide or/and 4-halogenodiphenyl sulfide and hydrogen sulfide in a molar ratio of 1:10 to 30 and a temperature of 200 to 350.
A method for producing parahalogenothiophenol, which is characterized by carrying out a gas phase reaction on a catalyst under conditions of °C. 3. The method according to claim 2, wherein the reaction space velocity is 30 to 1000/Hr. 4. The method according to claim 2, wherein the catalyst is activated carbon. 5 Claim 2 in which the catalyst is nickel sulfide
Method described. 6. The method according to claim 2, wherein the catalyst is alumina. 7. The method according to claim 2, wherein the catalyst is a combination of cobalt oxide, molybdenum, and alumina. 8. The method according to claim 2, wherein the catalyst is a combination of molybdenum oxide and alumina.