CH648028A5 - METHOD FOR PRODUCING N-CYCLOHEXYLBENZOTHIAZOL-2-SULFENAMIDE. - Google Patents

Description

The invention relates to a process for the preparation of N-cyclohexylbenzothiazole-2-sulfenamide by reacting 2-mercaptobenzothiazole with cyclohexylamine and an oxidizing agent. N-Cyclohexylbenzothiazol-2-sulfenamide is used as a safe accelerator in rubber vulcanization.

N-Cyclohexylbenzothiazol-2-sulfenamide is usually made by oxidizing the cyclohexylamine salt of 2-mercapto-3o benzothiazole with a solution of sodium hypochlorite or hydrogen peroxide:

sh snh h

+ h2o

The cyclohexylamine salt of 2-mercaptobenzothiazole can be prepared from the sodium, calcium or ammonium salt. In the form of these salts, 2-mercaptobenzene is obtained in the purification of the crude melt from 2-mercaptobenzothiazole. The process for the preparation of the sodium salt is described in CS-PS 114 693; in U.S. Patent 2,191,657; U.S. Patent 2,268,467; U.S. Patent 2,762,814; in DE-PS 855 564 and DE-AS 1 940 364; in GB-PS 642 597; GB-PS 665 668; GB-PS 1 106 577; the preparation of the calcium salt in CS-PS 113 006; in DE-AS 1 940 364 and that of the ammonium salt in the CS author acceleration 184 052.

The principle of all of these methods is the same. The prescribed amount of cyclohexylamine is added to the aqueous solution of the associated 2-mercaptoben-zothiazole salt and the resulting solution or suspension of

Cyclohexylamine salt of 2-mercaptobenzothiazole treated with a suitable oxidizing agent. The preparation of the 55 sulfenamides directly from the amine salt of 2-mercaptoben-zothiazole protects a whole series of documents, US Pat. No. 2,339,002; U.S. Patent 2,772,279; U.S. Patent 3,144,652; GB-PS 452 044; GB-PS 655 668; GB-PS 1 106 577;

GP-PS 519 617; GB Patent 1,289,407; DE-PS 615 580; 60 DE-AS 2 056 764; FR-PS 852 118; FR-PS 950 693;

FR-PS 1 549 002 and JA-AS 74110 664 and JA-AS 74134674.

In many cases, the methods mentioned have considerable shortcomings. The inorganic bases 65 used pass into the waste water in the form of salts, when the calcium salt of 2-mercaptobenzothiazole is used, the contaminated calcium sludge is obtained and the product must pass through the insoluble calcium compounds

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acidic laundry. If you start with ammonium salt, the demands on the production plant increase.

The sulfenamides that are made from the sodium salt are not of the required quality and therefore they are cleaned (for example: FR-PS 2 056 749;

DE-AS 1 940 365; GB-PS 756 464; US Pat. No. 2,762,814), which is associated with increased losses and more waste water.

It has now been found that N-cyclohexylbenzothiazole-2-sulfenamide of high purity can be produced by reaction of 2-mer captobenzothiazole, cyclohexylamine and sodium hypochlorite or hydrogen peroxide.

The process of the invention consists in first reacting 2-mercaptobenzothiazole with an excess of 1.5 to 5 mol, preferably 2.5 mol, of cyclohexylamine to 1 mol of 2-mercaptobenzothiazole and the resulting solution of the cyclohexylamine salt of 2-mercaptoben-zothiazole then oxidized with sodium hydrochlorite or hydrogen peroxide at a temperature of 20 to 70 ° C, advantageously 45 ° C, and the oxidation by-products are separated off. 2-mercaptobenzothiazole can enter the reaction in the form of the crude reaction product which is formed in the high pressure reaction of aniline, carbon disulfide and sulfur, and is free of volatile components, e.g. by blowing with an inert gas, or without prior purification.

The production process according to the invention guarantees high yield and purity of N-cyclohexylbenzothiazole-2-sulfenamide, the process being maximally simplified and the preparation of cyclohexylamine salt of 2-mercaptobenzothiazole and its oxidation taking place in one step. The advantage of the new manufacturing process is also the substantial reduction in the amount of waste and wastewater, which is of particular importance for the ecology.

The method of preparation of N-cyclohexylbenzo-thiazole-2-sulfenamide according to the invention is illustrated by the following examples.

example 1

118.8 g (0.6 mol) of 50% cyclohexylamine and 34.8 g technical grade 96% (0.2 mol) 2 were placed in a 500 ml four-necked flask equipped with a high-speed stirrer, thermometer, reflux condenser and dropping funnel -Mercaptobenzothiazole given. The contents of the flask were heated to the temperature of 85 ° C. with stirring, the solution of the cyclohexylamine salt of 2-mercaptobenzothiazole being formed, which was further cooled to the temperature of 45 ° C. An amount of 110 ml (16.7 g Cl + / 100 ml) sodium hypochlorite solution was added from the Triehter over a period of 60 minutes at a uniform rate. The temperature was maintained at 42-45 ° C after cooling. After adding about 3A of the volume of the sodium hypochlorite solution, a crystal product began to separate out of the reaction mixture. After the end of the addition, the reaction mixture was allowed to react for a further 30 minutes and then cooled to 20 ° C. The crystal product was separated from the by-products by filtration and washed on the filter with 1000 ml of 10% cyclohexylamine and then with 700 ml of water.

The wet product was dried to constant weight. The yield was 48.2 g, i.e. 91.2% of the theoretical amount of N-cyclohexylbenzothiazol-2-sulfenamide. Melting point 101.5 to 102 ° C; Sulfenamide content 99.7% (mass.); insoluble residue 0.14% (mass.).

The mother liquor and the first wash water (two-phase system) were combined and distilled under normal pressure of 0.1 MPa. 94.4 g of azeotropic mixture of the cyclohexylamine with water were obtained, which, after being supplemented with fresh cyclohexylamine, was returned to the process. The yield, calculated on the amount of cyclohexylamine entered, represents 94.2% of the theoretical value.

Example 2

The preparation procedure was as described in Example 10, but 79.2 g (0.4 mol) of 50% cyclohexylamine was used. 48.6 g of the product were isolated (91.9% of the theoretical value) with a melting point of 100 to 102 ° C., sulfenamide content 98.2% (mass.), Insoluble remainder 0.25% (mass.).

15

Example 3

The preparation procedure was as described in Example 1, but 200 g (1.0 mol) of 50% cyclohexylamine was used. 45.1 g of product 20 were isolated (85.3% of the theoretical value) with a melting point of 102 ° C., sulfenamide content 99.9% (mass.), Insoluble remainder 0.1% (mass.).

Example 4

25 The manufacturing process was as described in Example 1, but the temperature was 30 ° C during the addition of the sodium hypochlorite solution. 47.2 g of product were isolated (98.2% of the theoretical value) with a melting point of 99 to 101 ° C., sulfenamide content 98.9% (mass.), 30 insoluble remainder 0.9% (mass.).

Example 5

The manufacturing process was as described in Example 1, but the temperature during the addition of the 35 sodium hypochlorite solution was 70 ° C. 46.2 g of product were isolated (80.55% of the theoretical value) with a melting point of 101.5 to 102 ° C .; Sulfenamide content 99.5% (mass.), Insoluble remainder 0.15% (mass.).

40 Example 6

The preparation procedure was as described in Example 1, but 36.3 g of 92.0% crude reaction product of the high pressure reaction of aniline, carbon disulfide and sulfur were used. The yield was 45 48.0 g (90.8% of the theoretical value) of the product with melting point 101 to 103.4 ° C; Sulfenamide content 99.3% (mass.); insoluble residue 0.14% (mass.).

Example 7

The manufacturing process was as in Example 1

described, but 38.8 g of 86.3% crude reaction product of the high pressure reaction of aniline, carbon disulfide and sulfur were used. The yield was 46.4 g (87.7% of the theoretical value) of the product with 55 melting point 100 to 102 ° C; Sulfenamide content 98.8% (mass.); insoluble residue 0.15% (mass.).

Example 8

The manufacturing process was as described in Example 1 60, but 102.5 ml was used for the oxidation

(16.7 g of C1V100 ml of sodium hypochlorite were used. The yield was 45.3 g (85.7 g of the theoretical value) of the product, melting point 100 to 101 ° C.; sulfenamide content 99.8% (mass.); Insoluble residue 0. 17% (mass.).

65

Example 9

The manufacturing process was as described in Example 1, but instead of sodium hypochlorite

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added 184 g of 5% hydrogen peroxide as an oxidizing agent in the reaction. There were 46.1 g (87.1% of the theoretical value) of the product with melting point 101 to 102 ° C; Sulfenamide content 99.4% (mass.); Insoluble residue 0.13% (mass.) Obtained.

Example 10

The manufacturing process was as described in Example 6, but 184 g of 5% hydrogen peroxide were used for the oxidation. The yield was 46.0 g (87.0% of the theoretical value) of the melting point product

101 to 103 ° C; Sulfenamide content 99.2% (mass.); insoluble remainder 0.10% (mass.).

s Example 11

The production process was as described in Example 7, but 184 g of 5% hydrogen peroxide were used for the oxidation. The yield was 44.9 g (84.9% of the theoretical value) of the product with a melting point of 100 to 102 ° C .; Sulfenamide content 99.0% (mass.); insoluble remainder 0.10% (mass.).

B

Claims (5)

648028 2nd PATENT CLAIMS 1. Process for the preparation of N-cyclohexylbenzothiazole-2-sulfenamide of the formula I .s nh [I] by reacting 2-mercaptobenzothiazole with cyclo-hexylamine and an oxidizing agent, characterized in that first 2-mercaptobenzothiazole is allowed to react with an excess of 1.5 to 5 mol of cyclohexylamine to 1 mol of 2-mercaptobenzothiazole and the resulting solution of the cyclohexylamine salt of the 2nd -Mercaptobenzothi-azols oxidized with sodium hypochlorite or hydrogen peroxide at a temperature of 20 to 70 ° C and the by-products of the oxidation are separated. 2. The method according to claim 1, characterized in that the cyclohexylamine is used in an excess of 2.5 moles per mole of 2-mercaptobenzothiazole. 3. The method according to claim 1 or 2, characterized in that the Oxidaton is carried out at 45 ° C. 4. Application of the method according to one of claims 1 to 3 to the crude product of the reaction of aniline with carbon disulfide and sulfur to 2-mercaptobenzothiazole. 5. Application according to claim 4 to that of volatile components, e.g. by blowing through with an inert gas, is released crude reaction product. 20th