Process for producing bishalophenyl disulfide

Details Process for producing bishalophenyl disulfide Process for producing bishalophenyl disulfide

2002-09-20

2003-11-11

Vollano, Jean F. (Department: 1621)

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

Organic compounds

Sulfur containing

C568S065000

Reexamination Certificate

active

06646165

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for producing a bishalophenyl disulfide. The bishalophenyl disulfide is a useful compound which is used for a wide variety of applications including medicine, agricultural chemicals, functional materials and the like.
BACKGROUND ART
Conventional processes for producing a bishalophenyl disulfide include a process wherein a halothiophenol is oxidized. The halothiophenol can be prepared, for example, by converting a halobenzene into a methylthiohalobenzene with an alkali metal methylmercaptide, and making the same into a halomethylthiohalobenzene with a halogenating agent, followed by hydrolysis according to the process disclosed in Japanese Unexamined Patent Publication No. 40636/1997.
When the halothiophenol used as the raw material is free of impurities in production of a bishalophenyl disulfide, a bishalophenyl disulfide having a high purity can be obtained by usual oxidation. However, when a disulfide is produced by oxidizing a low-purity halothiophenol containing impurities such as halobenzene, halomethylthiohalobenzene, bishalothiophenylmethane or the like, a problem is posed in that it is difficult to separate the disulfide as the contemplated product from the oxide derived from impurities, and a bishalophenyl disulfide can not be obtained with a high purity in a high yield.
DISCLOSURE OF THE INVENTION
A principal object of the invention is to provide a process for industrially producing a bishalophenyl disulfide having a high purity in a high yield even when a low-purity halothiophenol is used as the raw material.
The present inventors conducted extensive research to achieve the foregoing object, and found that an alkali metal halothiophenolate produced by reaction of a halothiophenol with an alkali metal hydroxide is easily dissolved in an aqueous solution of alkali metal hydroxide and that the impurities in the halothiophenol are insoluble in water. Based on this novel finding, the present invention was completed.
The present invention provides the following processes for producing a bishalophenyl disulfide and the following process for producing a halothiophenol used as the raw material.
1. A process for producing a bishalophenyl disulfide represented by the formula (3)
wherein X
1
is a halogen atom and X
2
is a halogen atom or a hydrogen atom, the process comprising the steps of reacting a halothiophenol represented by the formula (1)
wherein X
1
and X
2
are as defined above with an alkali metal hydroxide to obtain an alkali metal halothiophenolate represented by the formula (2)
wherein X
1
and X
2
are as defined above, and M is an alkali metal atom and subsequently converting the alkali metal halothiophenolate into a disulfide with an oxidizing agent in the presence of a mineral acid.
2. The process according to item 1, wherein the alkali metal hydroxide is potassium hydroxide or sodium hydroxide.
3. The process according to item 1, wherein the mineral acid is hydrochloric acid.
4. The process according to item 1, wherein the oxidizing agent is hydrogen peroxide.
5. The process according to item 1, wherein the halothiophenol is 2-chlorothiophenol, 3-chlorothiophenol, 4-chlorothiophenol, 2-bromothiophenol, 3-bromothiophenol, 4-bromothiophenol, 2,3-dichlorothiophenol, 2,4-dichlorothiophenol, 2,5-dichlorothiophenol, 3,4-dichlorothiophenol, 3,5-dichlorothiophenol, 2,3-dibromothiophenol, 2,4-dibromothiophenol, 2,5-dibromothiophenol, 3,4-dibromothiophenol or 3,5-dibromothiophenol.
6. The process according to item 1, wherein the halothiophenol of the formula (1) is prepared by the steps of reacting a halobenzene represented by the formula (4)
wherein X
1
and X
3
are each a halogen atom and X
2
is a halogen atom or a hydrogen atom, with sodium thiomethoxide in the presence of a quaternary phosphonium salt to obtain a methylthiohalobenzene represented by the formula (5)
wherein X
1
and X
2
are as defined above, chlorinating the obtained methylthiohalobenzene with chlorine to obtain a chloromethylthiohalobenzene represented by the formula (6)
wherein X
1
and X
2
are as defined above, and n is an integer of 1 to 3, and hydrolyzing the obtained chloromethylthiohalobenzene in the presence of a lower alcohol or a base.
7. A process for producing a halothiophenol represented by the formula (1)
wherein X
1
is a halogen atom and X
2
is a halogen atom or a hydrogen atom, the process comprising the steps of reacting a halobenzene represented by the formula (4)
wherein X
1
and X
2
are as defined above, and X
3
is a halogen atom, with sodium thiomethoxide in the presence of a quaternary phosphonium salt to obtain a methylthiohalobenzene represented by the formula (5)
wherein X
1
and X
2
are as defined above, chlorinating the obtained methylthiohalobenzene with chlorine to obtain a chloromethylthiohalobenzene represented by the formula (6)
wherein X
1
and X
2
are as defined above, and n is an integer of 1 to 3, and hydrolyzing the obtained chloromethylthiohalobenzene in the presence of a lower alcohol or a base.
[Production of bishalophenyl disulfide]
In the invention, a halothiophenol of the formula (1) is reacted with an alkali metal hydroxide to give an alkali metal halothiophenolate of the formula (2).
Examples of the halogen atom represented by X
1
and X
2
in the halothiophenol of the formula (1) are Cl, Br and I among which Cl and Br are preferred. Specific examples of the halothiophenol used in the invention are 2-chlorothiophenol, 3-chlorothiophenol, 4-chlorothiophenol, 2-bromothiophenol, 3-bromothiophenol, 4-bromothiophenol, 2-iodothiophenol, 3-iodothiophenol, 4-iodothiophenol, 2,3-dichlorothiophenol, 2,4-dichlorothiophenol, 2,5-dichlorothiophenol, 3,4-dichlorothiophenol, 3,5-dichlorothiophenol, 2,3-dibromothiophenol, 2,4-dibromothiophenol, 2,5-dibromothiophenol, 3,4-dibromothiophenol, 3,5-dibromothiophenol, 2,3-diiodothiophenol, 2,4-diiodothiophenol, 2,5-diiodothiophenol, 3,4-diiodothiophenol, 3,5-diiodothiophenol, etc. Among them, it is suitable to use 2-chlorothiophenol, 3-chlorothiophenol, 4-chlorothiophenol, 2-bromothiophenol, 3-bromothiophenol, 4-bromothiophenol, 2,3-dichlorothiophenol, 2,4-dichlorothiophenol, 2,5-dichlorothiophenol, 3,4-dichlorothiophenol, 3,5-dichlorothiophenol, 2,3-dibromothiophenol, 2,4-dibromothiophenol, 2,5-dibromothiophenol, 3,4-dibromothiophenol or 3,5-dibromothiophenol.
The halothiophenol to be used in the invention is not limited to high-purity compounds. It is possible to use a halothiophenol having a purity of 30 to 97%, preferably 50 to 91%. Consequently the crude halothiophenol produced, e.g., from a halobenzene as the raw material can be used without purification.
The alkali metal hydroxide to be used in the invention is not limited and includes, for example, lithium hydroxide, potassium hydroxide, sodium hydroxide and the like. Among them, it is suitable from an economical viewpoint to use potassium hydroxide or sodium hydroxide. The amount of the alkali metal hydroxide to be used is usually 1 to 3 moles, preferably 1 to 2 moles, per mole of halothiophenol. When the alkali metal hydroxide is used in an amount of less than 1 mole, a satisfactory effect is unlikely to be achieved. On the other hand, more than 3 moles of alkali metal hydroxide used is unlikely to give the effect corresponding to the amount used and may be uneconomical. The alkali metal hydroxide is generally used in the form of an aqueous solution. Preferably the aqueous solution has a concentration of about 10 to about 40 wt %.
The temperature in the reaction between a halothiophenol and an alkali metal hydroxide is not limited, but usually −10 to 100° C., preferably 0 to 40° C. The reaction time is variable with the reaction temperature, but usually 5 minutes to 1 hour.
The alkali metal halothiophenolate resulting from the reaction between a halothiophenol and an alkali metal hydroxide is easily dissolved in an aqueous solution of alkali metal hydroxide. On the other hand, the impurities in the halothiophenol are insoluble in water. Consequently even when a lo

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