DE1903968B2 - METHOD FOR PRODUCING THIOPHENOLS - Google Patents

Description

The hydrogenative cleavage of aromatic dilufides under the influence of catalysts has been carried out for a long time

In US Patent 24 02 694 is about the Hydrogenic cleavage of dinaphthyl disulfide to naphthyl mercaptan on iron polysulfide contact reported Thereafter, the feed must be dry, and the catalyst is also before its use of the adhering water has been released. Both require a very considerable effort before the hydrogenation in advance.

The invention relates to the process for the preparation of thiophenols as defined in more detail in the claim.

The catalysts used can easily be obtained by precipitation of water-soluble cobalt or cobalt Manufacture nickel salts with sodium sulfide or polysullide. They do not require any further treatment and are Ready for salting immediately after filtering. Under the influence of these catalysts, aromatic substances become Disulfides hydrogenated to the corresponding thiophenols in high yields and excellent purity

The best way to proceed is to use the liquid or molten diphenyl disulfides Catalyst in amounts of about 0.5 to 10%, preferably 1 to 5%, added and at hydrogen pressures Hydrogenated from 150 atmospheres Solvents can be used in this process, however their absence leads to improved space-time yields. After the reactions stop sucks the thiophenols from the catalyst. Particularly noteworthy is the fact that> the catalysts retain their effectiveness unchanged even in the presence of water and can be reused as often as required can be. The process can be carried out continuously or batchwise.

Suitable aromatic disulfides are compounds of the general formula

where R = hydrogen, halogen or alkyl and π is an integer between 1 and 5.

example 1

13 g CoSO ₄ · 7H ₂ O are dissolved in 15 g of water at 40 ⁰ C and a solution of 6.2 g Na ₂ S containing 40% of water, dissolved in 15 g of water were added The precipitated cobalt sulfide is 4 times Washed sulfate-free with 25 ml of water each time, filtered off with suction and dried on a clay plate.

In a? 00 ml autoclave, 200 g of diphenyl disulfide containing 0.1% water, in the presence of the cobalt sulfide catalyst prepared above with 150 atm hydrogen for the reaction starts at \ Z8 "C and passes through increase to 180 ⁰ C within 10 Minutea The resulting thiophenol contains less than 0.1% diphenyl sulfide and 0.8% diphenyl disulfide; the yield is therefore 99.1%.

Example 2

13 g of CoSO ₄ · 7 H ₂ O, dissolved in 15 g of water at 40 °, are mixed with a solution of 6.2 g of Na ₂ S, which contains 40% water, in 15 g of water 25 ml of water each are washed free of sulfate, then filtered off with suction and reused while moist. 200 g of diphenyl disulfide are mixed with 2 g of water and the cobalt catalyst. sets and hydrogenates. The start of the reaction is at 139 °. The hydrogenation is complete after 15 minutes. It contains 99.8% thiophenol, less than 0.1% diphenyl sulfide and 0.1% diphenyl disulfide.

Example 3

200 g of diphenyl disulfide are mixed with 2 g of water and with a cobalt sulfide contact, which as in Example 2 has been prepared, at a

Hydrogen pressure of 150 atmospheres hydrogenated. The reaction starts at 138 ° and increases to 180 ° within 10 minutes. The reaction product is filtered off from the contact; it contains according to gas chromatography Analysis less than 0.1% diphenyl sulfide and 0.1% starting product Yield of thiophenol 99.8%

Example 4

As in Example 3, 200 g of diphenyl disulfide are used. to which 2 g of water have been added, hydrogenated in the presence of the cobalt sulfide catalyst recovered from Example 3. The reaction starts at 148 ° and ends after 20 minutes at 180 °. The thiophenene is 99.8% pure; it contains less than 0.1% diphenyl sulfide and less than 0.1% diphenyl disulfide.

Example5

13 g of NiSO ₄ · 7 H ₂ O are dissolved in 15 ml of water and a solution of 6.7 g of 60% sodium sulfide in 15 ml of water is added at 40 ° with stirring. The nickel sulphide precipitate formed is reused with water, as described in Example 2 for cobalt sulphide

200 g of diphenyl disulfide, to which 2 g of water have been added, are prepared in the presence of the Nickel sulfide catalyst hydrogenated. The reaction begins at 178 ° and ends at 200 ° after 40 minutes. The resulting thiophenol contains 0.8% diphenyl sulfide and less than 0.1% starting product; the The yield is 99.1% of theory. Th.

Example 6

3.08 g of sulfur flowers are added to a solution of 6.2 g of sodium sulfur in 16 ml of water and the mixture is stirred for 90 minutes at 70 °. The resulting yellow solution is added dropwise, with stirring, to a solution of 13 g of CoSO ₄ · 7 H ₂ O in 15 ml of water. The precipitate is filtered off with suction, washed free of sulfate 4 times with 25 ml of water each time and dried on a clay plate.

200 g of diphenyl disulfide, which contains 0.1% v / water, is used in the presence of this cobalt trisulfide contact Hydrogenated at 150 atm. Hydrogen pressure. The reaction begins at 140 ° and is completed in 7 minutes at 180 °. That resulting reaction product contains less than 0.1%

Diphenyl sulfide and 1.5% diphenyl disulfide. The yield of thiophenol is 98.4%.

Example 7

A cobalt sulfide catalyst produced according to Example 1 lysator is added to 200 g of diphenyl disulfide and 8 g of water and the mixture at 150 atmospheres with hydrogen hydrogenated. The reaction starts at 139 ° and is ended at 175 ° in the course of 10 minutes resulting thiophenol contains 0.1% diphenyl sulfide and 0.1% diphenyl disulfide, yield 99.8% of theory. Th.

Example 8

The cobalt sulfide catalyst recovered from Example 7 becomes 200 g of diphenyl disulfide, which is 0.8% Contains water and added 6 g of water and hydrogenated as described in Example 1. The reaction begins at 140 ° and is ended within 13 minutes at 180 ° The resulting thiophenol contains 0.1% Diphenyl sulfide and 0.1% diphenyl disulfide; Yield 99.8% of theory Th.

Example 9

The catalyst recovered from Example 8 is added to 200 g of diphenyl disulfide and 8 g of water, and, as indicated in Example 1, hydrogenated The reaction starts at 140 ° and ends at 175 ° in the course of 15 minutes. The resulting thiophenol contains less than 0.1% diphenyl sulfide and 0.1% diphenyl disulfide; Yield: 99.8% of theory.

Example 10

413 parts by weight of 2,2,5,5'-tetrachlorodiphenyl disulfide are added in the melt with a contact that contains approx. 40% water. It is produced in the following way: 7.7 parts by weight of crystallized material are dissolved Kobaitsulfatlieptahydrat in 35 parts by volume of water, brings the cobalt sulfide through a solution of 3.6 Parts by weight of sodium sulfide trihydrate in 35 parts by volume of water for precipitation, sucks the resulting black precipitate and wash with water. At 180 ° and a hydrogen pressure until ISOatü becomes hydrogenated After the reaction has ended, the reaction mixture is filtered off with suction and the mixture that remains Catalyst washed with benzene. Distillation of the combined filtrates gives a fraction which is 70 " and boiling 1.1-13 torr: 38 parts by weight of 2,5-dichlorothiophenol corresponding to a yield of 92% of theory. Th.

Example 11

139 parts by weight of bis (p-tert-butylphenyl) disulfide are mixed with 4% = 5.5 parts by weight of water and a catalyst is added which, by precipitating a solution from 15.2 parts by weight of cobalt sulfate in 70 parts by volume of water with a solution of 7.2 parts by weight of sodium sulfide trihydrate in 70 parts by volume of water, then suction and washing »with water. Hydrogenation is carried out under a hydrogen pressure of 150 atmospheres at a temperature of 180 °. The reaction is complete after ³ Å hours

The mixture is then filtered off with suction and the contact remaining in the filter is washed with benzene. 136 parts by weight of p-tert-butylthiophenol = approx. 98% of theory can be obtained from the filtrates by distillation. Th. obtain.

Claims (1)

Claim: Process for the preparation of thiophenols by reducing the corresponding diphenyl disulfide with hydrogen under increased pressure and in the presence of catalysts at temperatures between 60 and 300 ^° C., characterized in that a sulfide or polysulfide of cobalt or nickel is used as the catalyst