CS225046B1 - The one-stage production of n-cyclohexylbenzthiasole-2-sulphoamine - Google Patents

Description

SUMMARY OF THE INVENTION The present invention provides a process for the one-step production of N-cyclohexylbenzothiazole-2-sulfehamide of the formula

by reacting 2-mercaptobenzothiazole obtained as a crude reaction product from aniline, carbon disulfide and sulfur, with cyclohexylamine and an oxidizing agent carried out in one technological operation by simultaneously dosing all three reaction components.

_N-t Cyklohexylbenztiazol-2-sulfenamide are generally prepared by oxidation of the cyclohexylamine salt of 2-mercaptobenzothiazole, primarily obtained by reaction of the sodium, calcium, or an ammonium salt with cyclohexylamine. Subsequently, the cyclohexylamine salt of 2-mercaptobenzothiazole fc. oxidized with sodium hypochlorite, hydrogen peroxide, or other oxidizing agent.

All these procedures are mentioned in the literature review of Czechoslovakia. author's certificate no. 215 179 and have the drawbacks not only that the resulting sulfenamide is of relatively low quality but also that their inevitable accompanying appearance is the considerable volumes of chemically contaminated waste water and solid waste of various kinds.

In principle, a new process for the preparation of N-cyclohexylbenzothiazole-2-sulfenamide according to US Pat. of the author's certificate no. 215 179 substantially removes all these drawbacks by starting directly from the crude product of the high-pressure reaction of aniline, carbon disulphide and sulfur free of any volatile fractions and by using a molar excess of cyclohexylamine allows the

225046 2 contaminated 2-mercaptobenzothiazole directly, without dilution of preliminary refining stages. As a result, the production of N-cyclohexylbenzothiazole-2-sulfenamide is substantially simplified and favors the quality of the final product, economy and ecology of the process.

In practice, the oxidative condensation of the crude product of the reaction of aniline, carbon disulphide and sulfur deprived of volatile constituents is carried out according to the cited author's certificate at a molar ratio of 2-mercaptobenzothiazole: cyclohexylamine = 1: 2.80 and the primary formed cyclohexylamine salt at a molar ratio of 1: 1.275 and a temperature of 42 to 47 ° C. The N-cyclohexylbenzothiazole-2-sulfenamide recovered from the reaction medium after the addition of 75 to 80 mol% of the total amount of oxidizing agent is very fine and its separation from the mother liquors is complicated due to the high resistivity of the filter cake. This results in a high degree of clogging of the filter cake with the organic fractions of the smO1 solution in cyclohexylamine, resulting in the need for efficient separation devices and a relatively large volume of the cyclohexylamine wash.

We have found that the specific resistance of the filter cake decreases and the filtration rate of the product is substantially increased by the process of producing N-cyclohexylbenzothiazole-2-sulfenamide without preliminary preparation of the cyclohexylamine salt of 2-mercaptobenzothiazole. cyclohexylamine and an oxidizing agent according to the invention.

Advantage of the process for the preparation of N-cyclohexylbenzothiazole-2-sulfenamide by oxidative condensation of the crude product of the reaction of aniline, carbon disulfide and sulfur with cyclohexylamine and sodium hypochlorite in excess of cyclohexylamine without preliminary preparation of the cyclohexylamine salt of 2-mercaptobenzothiazole, m.p. j. in a single technological operation, the simultaneous dosing of all three reaction components results from a comparison of the two following examples.

Example 1

334 g (385 ml) of a 50% aqueous cyclohexylamine solution, 112 g of a molten reaction product of aniline, carbon disulphide and sulfur containing 90% by weight of 2-mercaptobenzothiazole are charged simultaneously to the 1000 ml reactor with stirrer, thermometer and cooling circuit. and 341 ml sodium hypochlorite containing 160 g Cl per liter solution. The molar ratio of 2-mercaptobenzothiazole: cyclohexylamine: Cl = 1: 2.8: 1.275, the reaction temperature is 42-47 ° C. After a holding period of 1 h, the mixture is passed from the reactor to a second 1000 ml stirred tank, where it is cooled to 20 ° C. Then the solid phase is separated from the mother liquors by filtration on a frit (S 3).

-2

The filter resistance is 1.50.10 m. The crystalline product on the frit is washed with 50 ml of a 10% aqueous cyclohexylamine solution, then with 700 ml of water and dried to constant weight at 75 ° C. Yield 145.2 g, m.p. j. 91.1% of theory for the inserted 2-mercaptobenzothiazole.

N-cyclohexylbenzothiazole-2-sulfenamide content: 99.4%

Melting point: 101.5 to 102.0 ° C

Stability at 160 ° C: 95 minutes

Insoluble residue in ethanol: 0.14%

Example 2

To a 1000 mL reactor with stirrer, thermometer, reflux condenser and dropping funnel was charged 334 g (385 mL) of a 50% aqueous cyclohexylamine solution and 112 g of molten crude reaction product of aniline, carbon disulfide and sulfur were added with stirring. 2-mercaptobenzothiazole. After the temperature has stabilized at 45 ° C, the mixture is kept under stirring for 1 hour to give the cyclohexylamine salt of 2-mercaptobenzothiazole. To the solution of this salt, 341 ml of sodium hypochlorite containing 160 g of Cl per liter of oxidizing agent are added over 1 hour. The molar ratio of 2-mercaptobenzothiazole: cyclohexylamine: Cl ⁺ = 1: 2.8: 1.275, the temperature during the oxidation is 42 to 47 ° C. Both operations, ie the preparation of the cyclohexylemine salt of 2-mercaptobenzothiazole as well as its oxidation, are carried out in one technological step, but in contrast to the procedure of Example 1, in two separate stages. The primary formation of the cyclohexylamine salt of 2-mercaptobenzothiazole and its subsequent oxidation results in a very fine suspension of the crystalline product which, upon cooling to 20 degrees C, is separated from the mother liquors by filtration on a frit (S 3).

-2

The filter resistance is 9.15-10 m. The fine product is washed on a frit with 100 ml of a 10% aqueous cyclohexylamine solution, then with 700 ml of water and dried to constant weight at 75 ° C.

Yield: 144.3 g, m.p. j. 90.5% of theory for 2-mercaptobenzothiazole loaded

N-cyclohexylbenzothiazole-2-sulfenamide content: 99.2%

Melting point a: 101 a ^-1 . 102.5

The stability of the 1ó0 ^<J C: 88 minutes

Insoluble residue in ethanol: 0.09%

Cyclohexylamine is recovered from the mother liquors similar to Example 1 by the method of U.S. Pat. of the author's certificate no. 221 005.

Claims (1)

A process for the one-step preparation of N-cyclohexylbenzothiazole-2-sulfenamide of the formula by reacting crude 2-mercaptobenzothiazole obtained as the product of the reaction of aniline, carbon disulfide and sulfur with cyclohexylamine and an oxidizing agent such as sodium hypochlorite or hydrogen peroxide. 2.1 to 2.9 moles per mole of 2-mercaptobenzothiazole and a temperature of 40 to 60 ° C, characterized in that the reaction of the crude 2-mercaptobenzothiazole with cyclohexylamine and sodium hypochlorite is carried out in a single technological operation by simultaneous dosing of all three reaction components.