CS215179B1 - Method of making the n-cyclohexybenzthiazol-2-sulphenamide - Google Patents

Abstract

A method for the production of N- cyclohexyl-benzothiazole-2- sulfenamide in which 2- mercaptobenzothiazole reacts with an excess of cyclohexylamine and the resulting cyclohexylamine salt of 2- mercaptobenzothiazole is then oxidized with an oxidant such as sodium hypochlorite at a temperature in the range of 20 to 70 DEG C. 2-mercaptobenzothiazole may be used in the form of the crude product formed by a high-pressure reaction of aniline, carbon disulphide and sulphur. N-cyclohexylbenzothiazole-2- sulfenamide may be employed as an accelerator in the vulcanization of rubber.

Description

The present invention provides a process for the preparation of N-cyclohexylabenzthiazole-2-sulfenamide by reacting 2-mercaptobenzothiazole, cyclohexylamine and an oxidizing agent. N-Cyclohexylbenzothiazole-2-sulfenamide is used as a safe vulcanizable rubber accelerator.

N-Cyclohexylbenzothiazole-2-sulfenamide is commonly prepared by oxidation of the cyclohexyl • amine salt of 2-mercaptobenzothiazole with sodium hypochlorite or hydrogen peroxide.

The cyclohexylamine salt of 2-mercaptobenzothiazole can be prepared from the sodium, calcium or ammonium salts. In the form of these salts aa, 2-mercaptobenzothiazole is obtained by refining the crude melt of 2-mercaptobenzothiazole. The preparation of the sodium salt is described, for example, in Czechoslovak Patent No. 114,693, in US Patents 2,191,657, 2,268,467, 2,762,814, in German Patents 855,564 and / DAS / 1,940,364, in British Patents 642 597, 655 668, 1 106 577, of calcium salt in Czechoslovakian patent no. 113 006, in Germany / DAS / Number 1 940 364 and of ammonium salt in Czechoslovakian author's certificate number 184 052.

The principle of all these procedures is the same. A prescribed amount of cyclohexylamine is added to the aqueous solution of the corresponding 2-mercaptobenzothiazole salt and the resulting solution of the 2-mercaptobenzothiazole cyclohexylamine salt is oxidized with a suitable oxidizing agent. A series of protection documents such as US Patents 2,339,002, 2,772,279 Nos. 044, 655 668, 1 106 577, 519 617, 1 289 407, German Patent Nos. 615 580, and NSR / DAS / 2 056 762, French Patent Nos. 852 118, 950 693, 1 549 002, Japanese Published Applications 74 110 664 , 74,134,674 protects the preparation of sulfenamides directly from the amine salt of 2-mercaptobenzothiazole.

In many cases, these processes have considerable shortcomings. The organic bases used will pass into the waste water in the form of salts, when the calcium salt of 2-mercaptobenzothiazole is used, contaminated calcium sludge is removed and the product must be freed from insoluble calcium compounds by acidic washing. If starting from the ammonium salt, the demands on the plant 2 are increased. The sulfenamides prepared from the sodium salt and the calcium salt of 2-mercaptobenzothiazole do not usually have the desired bone and are therefore purified (e.g., French Patent No. 2,056,749, NSR / DAS) No. 1,940,356, British Patent No. 756,464, US Patent No. 2,762,814 This is accompanied by an increase in losses and waste volume.

It has now been found that N-cyclohexylbenzothiazole-2-sulfenamide of high purity can be prepared by reacting 2-mercaptobenzothiazole, cyclohexylamine and sodium hypochlorite according to the invention.

SUMMARY OF THE INVENTION The present invention is characterized in that 2-mercaptobenzothiazole is first reacted with an excess of cyclohexylamine predetermining 1.5 to 5 moles of β, preferably 3 moles of cyclohexylamine per mole of 2-mercaptobenzothiazole, and the resulting solution of cyclohexylamine salt of 2-mercaptobezothiazole is 20 ^° to 70 ° C, preferably 40 ° to 45 ° C, and by-products of the oxidation and subsequent separation by filtration. 2-MerraaPooeezthiazole can be introduced into the reaction in the form of a crude reaction product resulting from the high-pressure reaction of aniline, carbon disulfide and sieves, either free of volatile constituents or prior to purification.

The process according to the invention guarantees a high yield and purity of N-cyclohexylbenzthiathl-2-uufenamide, the process being as simple as possible for the preparation of the cyclohexylamine salt of 2-meecaprazole and its oxidation in one step. which is particularly important in terms of ecology. '

The following examples illustrate the process for the preparation of the N-cyclopropyl-2-bisphenamide according to the invention.

Example 1

Do 500 ml S ^^ play. 1113.8 g / 0.6 moles were fed to a flask equipped with a speedometer, a thermometer with a cooler, and a drop drop. 50% cyclohexylamide and 34.8 g of industrial 96% (0.2 mol) 2-methylpertertzazole. The contents of the flask were taken with stirring at 85 ° C to give a solution of the 2-methyl-hexylamine salt of cyclohexyl amine, which was subsequently cooled to 45 ° C. A sodium hypochlorite solution of 110 m was added in a uniform stream from the separating funnel over a period of 60 m. (16.7 g Cl ⁺ / 100 ml) · The temperature was maintained at 40 ° C to 45 ° C with gentle cooling. After about 3/4 volume of sodium hypochlorite solution was added, a crystalline product began to precipitate from the reaction mixture. After the dosing was complete, the reaction mixture was reacted for 30 minutes and cooled to 20 ° C. The wet cake dreamed to a constant hioota. Yield: 48.2 g theory 91,2® i.e. cykloheJχ ^{N-R-2-leenrtiatll} sufernamidu. Melting point 101.5 0 to 102 ° C, sulfenamide content 99.7% by weight, insoluble residue 0.14 wt.

The mother liquors of the first rinsing water / two-phase system were subjected to (pellets at a normal pressure of 0.1 ° C) to obtain 94.4 g of an azeotropic mixture of cyclohexylamine with water, which was returned to the process after replenishment with fresh cyclohexqraamZnop. of the product calculated from the inserted cyclohexylamine represents 94.2% of theory.

Example 2

The preparation procedure was the same as in Example 1, but using pp 79.2 g (0.4 mol./50 O) cyclohexylamir. 48.6 g of product (91.9% of theory) were isolated with a melting point of 100 ° C to 102 ° C, 98.2 ® hiroo sulfanamide content ₄ insoluble residue 0.25 ® hmoo.

Example 3

The preparation procedure was the same as in Example 1 except 200 g (1.0 mol) was used.

45.1 g of product (85.3% of theory) and a melting point of 102 DEG C., a sulfenamide content of 99.9% by weight, an insoluble residue of 0.1% by weight were isolated.

Example 4

The preparation procedure was the same as in Example 1 but the temperature during the addition of sodium hypochlorite was 30 ° C. 47.2 g of product (89.2% of theory) were isolated with a melting point of 99-101 ° C, the sulfenamides content 98.9% by weight. 0.9% insoluble residue;

Example 5

The preparation procedure was the same as in Example 1 but the temperature during the addition of the sodium hypochlorite solution was 70 ° C. Isolated 42.6 g of product / 80.55 # of theory / mp 101.5 ^0-102 ° C, kettle contents sulfenamide 99.9 wt.%, The insoluble residue of 0.15% by weight.

Example 6

The preparation procedure was the same as in Example 1 but using 36.3 g of a 92.0% crude high pressure reaction product of aniline, carbon disulphide and sulfur. Yield 48.0 g / 90.8% of theory / product, m.p. - 103.5 ° C, sulfenamide content 99.3 wt.%, Insoluble residue 0.14 wt.

Example 7

The preparation procedure was the same as in Example 1, but using 38.8 g of 86.3% crude high pressure reaction product of aniline, carbon disulphide and sulfur. Yield 46.4 g (87.7% of theory / product), m.p. 100-102 ° C, sulfenamide content 98.8% by weight, insoluble residue 0.15% by weight.

Example 8

The preparation procedure was the same as in Example 1, but 102.5 ml (16.7 g Cl ⁺ / 100 ml) sodium hypochlorite was used for the oxidation. Yield 45.3 g (85.7%) of theory / product, melting point 100-101 ° C, sulfenamide content 99.8 wt%, insoluble residue 0.17 wt%.

Example 9

The preparation procedure was the same as in Example 1 but instead of sodium hypochlorite 184 g of 5% hydrogen peroxide was added to the reaction as an oxidizing agent. 46.1 g (87.1% of theory) of product are isolated, m.p. 101-102 ° C, sulfenamide content 99.4% by weight, insoluble residue 0.13% by weight.

Example 10 o

The preparation procedure was the same as in Example 6, but 184 g of hydrogen peroxide were used for the oxidation. Yield 46.0 g / 87.0% of theory / product, m.p.

101 DEG-103 DEG C., sulfenamide content 99.2% by weight. insoluble residue 0.10 wt.

Example 11

The preparation procedure was the same as. in Example 7, however, 184 g of hydrogen peroxide were used for the oxidation. Yield 44.9 g (84.9% of theory / product), m.p. 100-102 ° C, sulfenamides content 99.0% by weight, insoluble residue 0.10% wt.

Claims (2)

1. SpĎsob of N-cykloheexlberizziazol - ^ - sulfenamide of the formula I / I / 2-reakoiou oeekaato0bezttazolu a ^^ _d ^ kJ cyclohexyl ^ É ^ min and oxldadného agent, wherein aa, by first reacting 2-oeeraatotbezttazot with excess oyklohexylamínu in an amount of 1.5 to 5 moles of cyclohexylamine, preferably 3 moles of cyclohexylamine per mole of S-meecocatoobenziazole, and the resulting solution of the tylthexylanoate salt of 2-oecapptothezeziazole e is subsequently oxidized with β sodium hypochlorite or hydrogen peroxide at 20 to 70 ° C 45 ° C and oxidation by-products and separated by liltcácoou. 2. A process according to claim 1, wherein the reaction is carried out with 2-mercaptobenzidine. in the form of a crude reaction product of the reaction of angina, sulfur carbon and sulfur. devolatilized with inert gas or without prior purification.