CS254947B1 - A method for preparing 2,2'-dibenzothiazulide disuifide - Google Patents

Abstract

The solution concerns a method of preparing 2,2'-dibenzthiazolyl disulfide by oxidizing a 10 to 20% solution of 2-mercaptobenzthiazole in a mixture of aliphatic or alicyclic alcohol and water with a water content of 1 to 30% by mass. with a 10 to 30% aqueous solution of hydrogen peroxide at a temperature of 25 to 80 °C. The molar ratio of 2-mercaptobenzthiazole to hydrogen peroxide is 2.0:1.1 to 1.8. The solution can be used in the chemical industry.

Description

The invention relates to a process for the preparation of 2,2'-dibenzothiazolyl disulfide by oxidation of 2-mercaptobenzothiazole with hydrogen peroxide in an environment of a mixture of an aliphatic or alicyclic alcohol and water.

2,2-Dibenzothiazolyldisulfide is used as a vulcanization accelerator for natural and synthetic rubber.

The known processes for the preparation of 2,2'-dibenzothiazolyldisulfide are based on the oxidation of 2 mercaptobenzothiazole or its salts and use oxygen, ozone, sodium chlorine, chlorine and others as oxidizing agents.

The preparation of 2,2‘-dibenzothiazolyldisulfide by oxidation of the ammonium salt 2 of mercaptobenzothiazole with atmospheric oxygen in an aqueous medium and in the presence of organic cobalt value as a catalyst is the subject of SU 575 348.

By introducing oxygen into a mixture of 2-mercapto-benzothiazole, cobalt phthalocyanine disulfonate and a surfactant in dimethylformamide at 70 ° C, 2,2‘-dibenzothiazolyldisulfide in 97.9% yield and 99.3% purity can be prepared. (US 3,654,297).

Adding 3% sodium hypochlorite solution to 10% benzothiazole solution of technical 2-mercapto in dilute ammonia yields 2,2'-dibenzothiazolyldisulfide in 98-99% yield (CS 182 579).

Also known are ozone oxidation processes for 2-mercaptobenzothiazole in which the selectivity of 2,2'-dibenzothiazolyl disulfide formation is increased by lowering the reaction temperature to 0 ^J C.

According to DE 2 800 462 it is possible to prepare 2,2-dibenzothiazolyldisulphide in 98% yield and with a purity of 98.1% by adding separate streams of aqueous alkaline salt solution at 20 to 75 ^° C below the surface of a vigorously stirred aqueous medium. mercaptobenzothiazole and chlorine, maintaining the pH of the reaction mixture at 6-9.

2,2'-Dibenzothiazolyl disulfide in the form of granules of 0.1 to 1 mm in size makes it possible to prepare a process according to I 55160040 based on the oxidation of the water-soluble salts of 2-mercaptobenzothiazole in an aqueous-organic medium at a temperature below the boiling point of water.

Yields of 2,2‘-dibenzothiazolyldisulfide above 99% provide the electrochemical oxidative climatization of 2-mercaptobenzothiazole (US 2,385,416, DE 2,309,584, DE 2,743,629).

Methods for the preparation of 2,2-dibenzthiazolyldisulfide by oxidation of 2-mercaptobenzothiazole with hydrogen peroxide are also known. Reaction according to scheme:

, C-Sh 'and O - k x no. FROM

N.

c-p-s

The older processes (US 2,024,567, US 2,024,575) are based on the reaction of an alkaline aqueous solution of 2-mercaptobenzothiazole with hydrogen peroxide and require neutralization of the resulting reaction mixture with a mineral acid.

The process according to EP 8548 allows to prepare 2,2‘-dibenzothiazolylsulfide in 99% yield by oxidation of 2-mercaptobenzothiazole in aqueous suspension with hydrogen peroxide in the presence of EDTA or its alkali salts at 10 to 100 ° C for 0.5 to 50 h.

In the process of EP 112 794, 2,2'-dibenzothiazolyldisulphide is obtained in 95% yield by soaking a 10-20% suspension of 2-mercaptobenzothiazole in aqueous ammonia or amine solution with a 10% excess of hydrogen peroxide or alkyl hydropepoxide at 64-80 °. C. The product obtained contains 0.73 pens. unreacted 2-mercaptobenzothiazole.

The oxidation of 2-mercaptobenzothiazole with hydrogen peroxide in the presence of alkali metal, alkaline earth metal hydroxides or salts of these metals with 2-mercaptobenzothiazole is described in HU 32361.

2,2'-Dibenzothiazolyldisulfide in 98% yield can also be prepared by oxidizing 2-mercaptobenzothiazole with cumene hydroperoxide (US 4,143,045).

A disadvantage of the known processes is, in particular, the use of the 2-mer captobenzothiazole salt, which necessitates subsequent neutralization of the resulting reaction mixture to form considerable amounts of inorganic salts, or the use of catalysts.

These disadvantages make it possible to largely overcome the process for the preparation of 2,2'-dibenz thiazolyldisulfide by oxidizing 2-mercaptobenzothiazole with hydrogen peroxide according to the invention, which is characterized in that a 10 to 20% solution of 2-mercaptobenzothiazole in a mixture of aliphatic or alicyclic alcohol and water with a water content of 1 to 30 wt. is reacted with a 10 to 30% aqueous hydrogen peroxide solution at 25 to 80 ° C. The molar ratio of 2-mercaptobenzothiazole to hydrogen peroxide is 2.0: 1.1 to 1.6.

It has been found to be particularly advantageous if the process according to the invention is carried out in an environment of 75 to 95% by weight. % of an aqueous aliphatic or alicyclic alcohol, using 10 to 20 wt.% hydrogen peroxide; % in a molar excess of 1.2 to 1.3 at a concentration of 2-mercaptobenzothiazole in a reaction medium of 10 to 20 wt. and at a temperature of 40 to 70 ° C.

The process of the invention is a one-step process,

It does not require the use of a catalyst, it works with the free 2-norptaptobenzothiazole, so that no neutralization of the resulting reaction sound is required, no anorous waste salts are formed. A further advantage of the process according to the invention is that impurities from the starting 2-mercaptobenzothiazole enter the used solvent, which allows washing not only with high purity 2-nercaptobenzothiazoloin but also with crude or refined 2-mercaptobenzothiazole. The solvent used can be used in the process after regeneration with p. The product is readily isolated from the reaction mixture by filtration. The yield of 2,2'-dibenzoisolyldisullide tocol is always greater than 98% and the purity is 99%. The process according to the invention can be carried out in a continuous or continuous manner.

The following examples illustrate the invention.

Example !

10 g of 99% 2-morkiiptobenzyl chloride (hereinafter 2 MBTj) were mixed in a reaction vessel with a mixture of 90 g of isopropyl alcohol and 10 g of water. The solution was heated to 40 ° C and 12.4 g of 10% hydrogen puroxyl (molar) was added. ratio of 2-MBT: HO-.

2.0: 1.23) and the reaction mixture was maintained at 40 ° C for 90 minutes. After 90 min, the suspension was filtered and the product obtained was dried.

9.66 g (98.2%) of 2,2'-dibenzothiazolyldisulphide with a purity of 99.48% were obtained.

Example 2

In the reaction vessel, 10 g of 99.1 percent 2-MBT was mixed with a mixture of 105 g of cyclohexanol and 5 g of water, to the mixture. at 60 ° C, 6.6 g of 20% sodium hydrogen peroxide (molar ratio 2-MBT: H 2 O 2 = 2.0:

: 1.31) and the mixture was maintained at this temperature for 1 hour.

After 1 hour, 9.7 g (98.5%) of 2,2'-dibenzothiazolyldisulfide with a purity of 99.56% was obtained by filtration and drying.

Example 3

10 g of 90% 2-MBT was mixed in a reaction vessel with a mixture of 120 g of ethanol and 52 g of water, and 4.67 g of 30% hydrogen peroxide (mole ratio of 2-MBT) was added to the mixture at a temperature of three degrees Celsius. : H _; O;

2.0: 1.39) and held at this temperature for 2 hours.

After 2 hours, filtering and drying yielded 9.72 g (98.7%) of 2,2'-dibenzyl azolyldisulfide with a purity of 99.66%.

Example 4

In the reaction vessel, 20 g of 99.1% 2-MBT was mixed with a mixture of 180 g of n-butyl alcohol and 20 g of water, and 24.78 g of 10% hydrogen peroxide (mole ratio 2-) were added to the mixture at 70 ° C. MBT: H 2 O 2 = - 2.0: 1.23) and held at this temperature for 1 hour.

After 1 hour, 19.3 g (98%) of 2,2'-dibenzothiazolyldisulfide having a purity of 99.53% was obtained by filtration and drying.

Example 5

In the reaction vessel, 19 g of 98.3% 2-MBT was mixed with a mixture of 100 g of iso-butyl alcohol and 15 g of water, and 4.43 g of 30% hydrogen peroxide (mol. Ratio 2-MBT: 2.0: 1.34) and the mixture was held at this temperature for 90 minutes.

After 90 minutes, filtering and drying yielded 9.68 g (99.1%) of 2,2'-diheozthiazolyldisulfide with a purity of 99.40%.

Example 6

In the reaction vessel, 10 g of 96-percent 2-MBT was mixed with a mixture of 99 g of isopropviaicobol and 1 g of water, and 4.23 g of 30% peroxide was added to the mixture at 60 ° C (optional 2-MBT: H2O2 ratio). - 2: 1.3) and the mixture was held at this temperature for 2 hours.

After 2 hours, 9.4 g (98.5%) of 2,2'-dibenzothiazolyldisulfide having a purity of 99.3% were obtained by filtration and drying.

Example 7

In the reaction vessel, 10 g of 90 percent 2-MBT (crude melt) was mixed with a mixture of 150 g of i-butanol and 5 g of water, and 4.88 30% hydrogen peroxide (mole ratio) was added at 70 ° C. The 2-MBT: PbCl = 2.0: 1.6 was maintained at this temperature for 2 hours.

After 2 hours, filtering and drying yielded 8.5 g (95%) of 2,2'-dibenzothiazolyldisulfide with a purity of 99%.

Example 8

In the reaction vessel, 10 g of 98.3 µl of 2-MBT was mixed with a mixture of 60 g of ethanol and 5 g of water, and 5.0 g of 30% hydrogen peroxide (mole ratio 2-) were added to the mixture at 25 ° C. MBT: H 2 O 2 = 2.0: 1.5) and held at this temperature for 5 hours.

After 5 hours, 9.6 g (98.3%) of 2,2'-dibenzothiazolyldisulfide with a purity of 99.08% was obtained by filtration and drying.

Example 9

In the reaction vessel, 10 g of 98.3% 2-MBT was mixed with a mixture of 150 g of ethylhexanol and 2 g of water, and 3.66 g of 30% hydrogen peroxide (mole ratio 2-MBT: H2O2 = 2.0) was added. : 1.1 j at temperature

5'9.47 ° C. The reaction mixture was held at this temperature for 50 minutes.

After 90 minutes, filtering and drying yielded 9.32 g (95.4%) of 2,2'-dibenzothiazolyldisulfide with a purity of 99.75%.

Example 10

A 10% 99% 2-MBT solution in a mixture of n-butyl alcohol and 5% water was charged at a rate of 120 g to a 100 mL continuous flow reactor. ^_I h and 30% hydrogen peroxide at a rate of 4.92 g. h ^-1 (molar ratio 2-MBT: H 2 O 2 = 2.0: 1.22). At 60 ° C, a slurry of 2,2'-dibenzothiazolyldisulfide in wet butanol was obtained at a conversion of ,498.4% at the reactor outlet.

The product obtained had a purity of 99.53%. Example 11

Into a flow stirred reactor

Claims (1)

SUBJECT Process for the preparation of 2,2'-dibenzothiazole disulfide by oxidation of 2-mercaptobenzothiazole with hydrogen peroxide, characterized in that a 10-20% solution of 2-mercaptobenzothiazole in a mixture of an aliphatic or alicyclic alcohol and water containing 1 to 30% water at a rate of 200 ml was dosed at 8% a solution of 98.3% 2-MBT in a mixture of isopropyl alcohol and 9% water at a rate of 147 g. tr ¹ and 30% hydrogen peroxide at Ný 5.38 g. h ^-1 (molar ratio 2-MBT: H 2 O 2 = 2.0: 1.39). At 50 ° C, 99% conversion was achieved, the purity of the obtained 2,2‘-dibenzothiazolyldisulfide was 99.4%. Example 12 A 20% solution of 99.8% 2-MBT in a mixture of isobutyl alcohol and 10% water at a rate of 75 g was charged to a 100 mL continuous flow reactor. h ¹ and the 10% hydrogen peroxide at Ný 19.1 g. h ^-1 (molar ratio 2-MBT: H 2 O 2 - 2.0: 1.26). At 70 ° C, 98.2% conversion was achieved, the purity of the obtained 2,2‘-dibenzothiazolyldisulfide was 99.58%. OF THE INVENTION is reacted at 25 to 80 ° C with a 10 to 30% aqueous hydrogen peroxide solution, the molar ratio of 2-mercaptobenzothiazole to hydrogen peroxide being 2.0: 1.1 to 1.6.