2,2'-Dithiobis(benzothiazole) (DM) is an excellent accelerant for rubber vulcanization. It is widely used in rubber industry meanwhile it is a pharmaceutical intermediate with high activity.

Uses

In recent years, DM was used to synthesize benzothiazole ester which is a precursor drug for cephalosporin antibiotics. The melting point of industrial grade DM used in rubber industry is required to reach 170 ºC. However, the DM used in pharmaceutical industry requires its melting point above 180 ºC, with fewer impurities, high activity, facilitating organic synthesis and quality control in pharmaceutical industry. 2,2'-Dithiobis(benzothiazole) produced from M is generally oxidized in aqueous solutions with various oxidants, such as air, chlorine, sodium hypochlorite, potassium bromate, ozone, hydrogen peroxide etc.

Improve purities

The purities of DM are different due to their different oxidation capacity. However, their melting points are all under 175 ºC and thus do not meet the requirements (high melting point, short melting range, few impurities and good quality) of the pharmaceutical industry. Many researchers have concentrated their work on this improvement. Nolte et al. used DMBA as the solvent, O2 as an oxidant, the product purity and yield were all above 99 %, but the melting point was relatively low. It is used O2 as an oxidant, acetonitrile as solvent to prepare high purity DM with the presence of CsF-Celite.

Preparation

Refined 2-mercaptobenzothiazole was produced by recrystallization from 2-mercaptobenzothiazole with industrial grade and oxidized to 2,2'-dithiobis(benzothiazole), using oxygen as an oxidant, nitric oxide as a oxygen carrier and alcohols as solvents, in a circulating fluidized reactor under one-step oxidation. 2,2'-Dithiobis(benzothiazole) was thus obtained with high purity up to 99 %, melting point at 183 ºC, high yield over 98 %, through the optimization of reaction parameters as reaction time, temperature, reactants ratio, with less waste generation and emission during the production process. Alcohol solvents can be reused after purification.

Safety Profile

Poison by intravenous andintraperitoneal routes. Slightly toxic by ingestion.Experimental teratogenic and reproductive effects.Questionable carcinogen with experimental tumorigenicdata. Mutation data reported. When heated todecomposition it emits over.