CS256573B1 - Process for producing diaminoiodenyl disulfide - Google Patents

Abstract

Method for producing diaminodiphenyl disulfide by alkaline hydrolysis of benzothiazole, oxidation of sodium salt of 2-aminothiophenolate of sodium with hydrogen peroxide while aerating the reaction mixture with air. The solution relates to the field of organic technology and can be used in the production of additives for polymeric, plastic and volcanic materials.

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of diamine diphenyl disulphide by alkaline hydrolysis of benzothiazole, oxidation of sodium salt of 2-aminothiophenol with hydrogen peroxide and the interaction of air oxygen.

Use of the subject matter of the present invention is within the scope of the use of benzothiazole, which is produced as a by-product in high-pressure synthesis.

2-mercaptobenzothiazole; by reaction of anilyne, carbon disulphide and sulfur. The benzothiazole obtained in the high-pressure synthesis of 2-mercaptobenzothiazole is purified by rectification under reduced pressure followed by hydrolysis of the pure component v. an alkaline liquor to form the sodium salt of 2-aminothiophenol.

NHCH---NonOri [Of yycocy ..

Numerous methods of alkaline hydrolysis of benzothiazole and its derivatives are known. So eg. Hoffman (Ber. August 13, 1880) prepared the sodium salt of 2-aminothiophenol by melting benzothiazole with sodium hydroxide.

In the next period, it was found that relatively milder conditions, e.g. hydrolysis of excess concentrated sodium hydroxide over 3 hours (British Pat. 558,887). According to the process of said patent, unchanged benzothiazole is distilled off with steam. The dependence of the rate of hydrolysis on the concentration of the alkali hydroxide used and the temperature are also documented.

To isolate free 2-aminothiophenol, procedures are described to acidify an aqueous solution of sodium 2-aminothiophenol with hydrochloric or acetic acid (USP 2 791612).

Boggust and Cocker I. Chem. Soc.

355 1949 discloses the possibility of opening a thiazole ring with hydrazine hydrate in an alcohol environment to form 2-aminothiophenol and by-products such as N2 and formaldehyde.

The treatment of 2-aminothiophenol or its sodium salt to 2,2'-diamino-diphenyl disulfide by oxidation with potassium dichromate is already described by Hoffman (Ber. 13. 8. 1880). Usually hydrogen peroxide is used as the oxidizing agent, but procedures using air alone as the oxidizing agent are known.

In practice, the procedure according to MS. pat. 108 079, according to which benzothiazole is subjected to alkaline cleavage followed by oxidation of the 2-aminothiophenol salt with hydrogen peroxide to 2,2'-diamino-diphenyl disulfide in the presence of chlorobenzene.

FROM

^{NC1 + Η Λ,} ~, NH ₂

N @ a C 1-2. KO

c.

A disadvantage of the conventional process is that sodium aminothiophenolate and H2O2 are dosed at a molar ratio of 2 to 1.83 to 1.77; t. j. using a molar excess of hydrogen peroxide.

The present inventors have found that in the manufacture of diamine diphenyl disulfide by oxidation of sodium amine thiophenolate with hydrogen peroxide, diamine diphenyl disulfide can be produced by oxidation of sodium aminothiophenolate with hydrogen peroxide with air oxygen, wherein the molar ratio of sodium aminothiophenolate to hydrogen peroxide is 2 to 1.07 to 1.1; while aerating the reaction mixture.

Using the process of the present invention, a high purity product is obtained while maintaining the process yield.

The present invention can be used in the manufacture of diamine diphenyl disulfide, respectively. in the manufacture of 2,2‘-dibenzoyldiaminodiphenyldisulfide, which is used as a peptizing agent.

The examples illustrate the invention but do not limit its scope.

'•' «γ · Example 1

225 kg of Na-aminothiophenol Na salt (1.53 kmol) and 2350 L of water were metered from the tank into an oxidation boiler equipped with a stirrer, a duplicator for cooling, and an air inlet to purge the reaction mixture. The contents of the boiler were cooled to 10 ° C. The oxidation is carried out at a temperature of 10-15 ° C by adding 35% H 2 O 2 from the measuring cup while continuously aerating the solution with air. 48 kg of 35% H 2 O 2 (0.84 mole) were used. 189 kg of diamine-diphenyldisulphide with a melting point of 134 ° C were obtained.

Example 2

260 kg of o-aminothiophenol Na-salt (1.76 kmol) and 2300 liters of water were metered from the tank into an oxidation boiler equipped with a stirrer, a duplicator for cooling and an air inlet to aerate the reaction mixture. The contents of the boiler were cooled to 10 degrees C. With constant air supply at 10-15 ° C, 35% H 2 O 2 was added in an amount of 52 kg (0.885).

Upon completion of the oxidation, 2/8 kg of diamine diphenyl disulfide having a melting point of 134 ° C was obtained.

Claims (2)

1. The process for producing diamine diphenyl disulfide by alkaline hydrolysis of benzothiazole, by oxidation of sodium 2-aminothiophenolate sodium with hydrogen peroxide is characterized in that sodium 2-aminothiophenolate is oxidized by peroxide. BACKGROUND OF THE INVENTION hydrogen at a dosage of 2-aminothiophenolate sodium and H2O2 at a molar ratio of 2 to 1.02 to 1.1; while aerating the reaction mixture.