JP2007204453A - Method for producing alkenyl mercaptan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an alkenyl mercaptan from an alkenyl halide and an alkali metal hydrosulfide in high yield. <P>SOLUTION: An alkenyl halide is made to react with an alkali metal hydrosulfide in a binary phase solvent composed of an organic solvent and water in the presence of a phase transfer catalyst. The reaction is carried out while supplying the alkenyl halide to a binary phase mixture composed of the organic solvent, water and the alkali metal hydrosulfide. The supply of the alkenyl halide is started after adjusting the pH of the aqueous phase of the binary phase mixture to 8-12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a process for producing alkenyl mercaptans from alkenyl halides and alkali hydrosulfides. Alkenyl mercaptans are useful, for example, as raw materials for pharmaceuticals and agricultural chemicals.

  As one of the methods for producing mercaptans, a method of reacting a corresponding halide with an alkali hydrosulfide in the presence of a phase transfer catalyst is known. For example, in JP-A-62-294652 (Patent Document 1), when a substituted benzyl mercaptan is produced by reacting a substituted benzyl halide with an alkali hydrosulfide, an organic solvent and a solvent are used in the presence of a phase transfer catalyst. It has been proposed to carry out the reaction in a two-phase solvent composed of water, preferably by adding an acid. Specifically, an organic solvent, water, a substituted benzyl halide and an acid are charged, and an alkali hydrosulfide is added thereto. It is disclosed that the reaction is carried out while supplying an aqueous solution. In addition, in JP-A-4-257557 (Patent Document 2), when an aralkyl mercaptan or an alkyl mercaptan is produced by reacting an aralkyl halide or an alkyl halide with an alkali hydrosulfide, in the presence of a phase transfer catalyst, It has been proposed to carry out the reaction in water without using an organic solvent under pressure of hydrogen sulfide. Specifically, an aqueous solution of alkali hydrosulfide is charged and pressurized with hydrogen sulfide, and aralkyl halide is added thereto. It is disclosed to carry out the reaction while supplying.

JP-A 62-294852 JP-A-4-257557

  However, in these conventional methods, the yield of mercaptans was not always sufficient. In particular, when an alkenyl halide is used as a halide to obtain an alkenyl mercaptan, it is difficult to produce the alkenyl mercaptan with a high yield. Accordingly, an object of the present invention is to provide a method capable of producing alkenyl mercaptan with good yield from alkenyl halide and alkali hydrosulfide.

  As a result of diligent research, the present inventors conducted a reaction between an alkenyl halide and an alkali hydrosulfide in a two-phase solvent consisting of an organic solvent and water in the presence of a phase transfer catalyst, under a predetermined charge supply condition. It has been found that the above-mentioned object can be achieved by adopting it, and the present invention has been completed. That is, the present invention is a method for producing an alkenyl mercaptan by reacting an alkenyl halide and an alkali hydrosulfide in a two-phase solvent consisting of an organic solvent and water in the presence of a phase transfer catalyst, The reaction is carried out while supplying the alkenyl halide to the two-phase mixture composed of an organic solvent, water and an alkali hydrosulfide, and the pH of the aqueous phase of the two-phase mixture is adjusted to 8 to 12, and the alkenyl halide is adjusted. The present invention provides a method for producing alkenyl mercaptan characterized by starting the supply of the above.

  According to the present invention, alkenyl mercaptan can be produced with good yield from alkenyl halide and alkali hydrosulfide.

  As the raw material alkenyl halide, alkenyl chloride or alkenyl bromide is usually used. Examples of the alkenyl include 2-propenyl (allyl), 2-methyl-2-propenyl (methallyl), 2-butenyl (crotyl). ), 3-butenyl, 3-methyl-2-butenyl (prenyl), 2-pentenyl, 3-pentenyl, 4-pentenyl and the like. Among them, the method of the present invention is advantageously employed when 2-alkenyl mercaptan is produced using 2-alkenyl halide, particularly lower 2-alkenyl halide having about 3 to 5 carbon atoms as a raw material.

  A corresponding alkenyl mercaptan is obtained by reacting the alkenyl halide as described above with an alkali hydrosulfide. As the alkali hydrosulfide, lithium hydrosulfide, sodium hydrosulfide or potassium hydrosulfide is usually used, and the amount used is usually 1 mol times or more, preferably 1.05 to 2 mol times with respect to the alkenyl halide. is there.

  The above reaction can proceed smoothly in the presence of a phase transfer catalyst in an oil / water two-phase mixed solvent composed of an organic solvent and water.

  Examples of the phase transfer catalyst include tetra-n-ethylammonium bromide, tetra-n-ethylammonium chloride, tetra-n-butylammonium bromide, tetra-n-butylammonium chloride, tetra-n-butylammonium hydrogensulfate, In addition to quaternary ammonium salts such as triethylbenzylammonium chloride and quaternary phosphonium salts such as tetra-n-butylphosphonium bromide, crown ethers, cryptands, and the like can be given. Of these, quaternary ammonium salts are preferably used. The amount of the phase transfer catalyst used is usually 0.001 to 0.2 mol times, preferably 0.05 to 0.1 mol times with respect to the alkenyl halide.

  As the organic solvent, an oil-water two-phase mixed solvent is used, so that it is immiscible with water. For example, aliphatic hydrocarbons such as hexane, heptane, and octane; cyclopentane, cyclohexane, etc. Alicyclic hydrocarbons, aromatic hydrocarbons such as benzene, toluene, xylene; Halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane; Halogenated aromatics such as monochlorobenzene and dichlorobenzene Examples thereof include hydrocarbons; ethers such as diethyl ether and dibutyl ether; esters such as ethyl acetate and butyl acetate. Of these, aromatic hydrocarbons are preferably used.

  The amount of the organic solvent used is usually about 0.5 to 5 times by weight with respect to the alkenyl halide, and the amount of water used is usually about 0.5 to 5 times by weight with respect to the alkali hydrosulfide. The ratio of the organic solvent to water used is usually about 1/5 to 5/1, expressed as the weight ratio of organic solvent / water.

  In the present invention, an organic solvent, water and an alkali hydrosulfide are charged to form a two-phase mixed solution, and the above reaction is performed while supplying an alkenyl halide thereto. Then, the supply of the alkenyl halide is started in a state where the pH of the aqueous phase of the charged solution, that is, the phase of the aqueous solution of alkali hydrosulfide is adjusted to 8 to 12, preferably 9 to 11. Thereby, by-products, such as dialkenyl sulfide, can be suppressed and the yield of alkenyl mercaptan can be increased. The phase transfer catalyst is usually charged together with an organic solvent, water and an alkali hydrosulfide.

  The pH of the aqueous phase is adjusted depending on the concentration of the aqueous solution of alkali hydrosulfide, but it usually has a pH exceeding 12. Therefore, the acid may be added by adding an acid. Examples of the acid include hydrochloric acid and sulfuric acid. Such inorganic acids are preferably used. In addition, as the alkenyl mercaptan is supplied, the pH of the aqueous phase usually decreases. However, this pH may be decreased depending on the outcome, and for example, a base may be added to keep the pH above a predetermined value. Good.

  The alkenyl halide is preferably supplied after cooling. As a result, local temperature rise is suppressed, or side reactions of the generated alkenyl mercaptan, for example, a reaction in which two molecules of alkenyl mercaptan are oxidized to form dialkenyl disulfide, or a mercapto group of alkenyl mercaptan is different. Reactions in which two or more adducts are formed by addition to the double bond of alkenyl mercaptan, reactions in which alkenyl mercaptan reacts with alkenyl halide to form dialkenyl sulfide, and the like can be suppressed. The reaction between the alkenyl halide and the alkali hydrosulfide is an exothermic reaction, and the side reaction as described above tends to occur at higher temperatures. However, the alkenyl halide can be easily removed by cooling and supplying. The cooling temperature of the alkenyl halide is usually about −20 to 5 ° C., although it depends on the type.

  The reaction temperature is usually 0 to 100 ° C, preferably 30 to 50 ° C. Moreover, although reaction is normally implemented by the normal pressure vicinity, you may carry out under pressure or pressure reduction as needed.

  The post-treatment operation after the reaction is appropriately selected. When the reaction mixture is separated into oil and water, an organic solvent solution of alkenyl mercaptan is obtained as the organic phase. The solution thus obtained can be used for various purposes after being purified by washing or distillation, if necessary.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
In a glass reactor equipped with a reflux condenser, a thermometer, a stirrer, and a jacketed dropping funnel, 54.31 g (0.678 mol) of sodium hydrosulfide hydrate (containing 70% by weight of sodium hydrosulfide) and 47 of water .17 g, 37.74 g of toluene and 25.29 g (0.062 mol) of a 55.5 wt% aqueous triethylbenzylammonium chloride solution were added and stirred. Next, 8.47 g (0.046 mol) of 20 wt% hydrochloric acid was added to adjust the pH of the aqueous phase to 9.5 and warmed to 40 ° C. 47.17 g (0.616 mol) of allyl chloride was placed in a jacketed dropping funnel and cooled to −2 to 5 ° C., and the cooled allyl chloride was maintained for 3 hours while maintaining the temperature of the reaction solution at 40 ° C. The solution was added dropwise and further kept at 40 ° C. for 3.3 hours. The pH of the aqueous phase after this incubation was 8.2. The obtained reaction liquid was cooled to 0 to 10 ° C., 56.60 g of water was added to dissolve the precipitated sodium chloride, and then oil-water separation was performed. As an organic phase, 82.65 g of a toluene solution of allyl mercaptan was added. Obtained. This solution was analyzed by gas chromatography [internal standard method using flame ionization detector (FID)]. As a result, the content of unreacted allyl chloride was 0.03 g (0.0004 mol), and the content of allyl mercaptan was 41. The conversion rate of allyl chloride was 99.9%, and the yield of allyl mercaptan based on allyl chloride was 91.3%.

Comparative Example 1
In the same reactor as in Example 1, 108.59 g (1.356 mol) of sodium hydrosulfide hydrate (containing 70 wt% of sodium hydrosulfide), 94.34 g of water, 75.47 g of toluene and 55.5 wt% An aqueous solution of triethylbenzylammonium chloride (50.59 g, 0.123 mol) was added and stirred and heated to 40 ° C. At this time, the pH of the aqueous phase was 14. 94.34 g (1.233 mol) of allyl chloride was placed in a jacketed dropping funnel and cooled to −2 to 5 ° C., and the cooled allyl chloride was maintained for 3 hours while maintaining the temperature of the reaction solution at 40 ° C. The solution was added dropwise and further kept at 40 ° C. for 2.3 hours. The obtained reaction solution was cooled to 0 to 10 ° C., and 113.21 g of water was added to dissolve the precipitated sodium chloride, followed by oil-water separation. Obtained. As a result of analyzing this solution by gas chromatography (same as above), the content of unreacted allyl chloride was 0.47 g (0.006 mol), and the content of allyl mercaptan was 75.03 g (1.012 mol). The conversion of chloride was 99.5%, and the yield of allyl mercaptan based on allyl chloride was 82.1%.

Claims (3)

A method for producing an alkenyl mercaptan by reacting an alkenyl halide and an alkali hydrosulfide in a two-phase solvent consisting of an organic solvent and water in the presence of a phase transfer catalyst,
The reaction is carried out while supplying the alkenyl halide to the two-phase mixture composed of an organic solvent, water and an alkali hydrosulfide, and the pH of the aqueous phase of the two-phase mixture is adjusted to 8 to 12, and the alkenyl halide is adjusted. The production method of the alkenyl mercaptan characterized by starting supply of this.   The process according to claim 1, wherein the organic solvent is an aromatic hydrocarbon. The method according to claim 1 or 2, wherein the alkenyl halide is a 2-alkenyl halide.