Benzothiazole-2-Thiol

Abstract

[149-30-4] C7H5NS2 (MW 167.25) InChI = 1S/C7H5NS2/c9-7-8-5-3-1-2-4-6(5)10-7/h1-4H,(H,8,9) InChIKey = YXIWHUQXZSMYRE-UHFFFAOYSA-N (reagent whose major application in synthetic organic chemistry is in olefinations) Alternate Names: 2(3H)-benzothiazolethione, 1,3-benzothiazole-2-thiol, 2-mercaptobenzothiazole, MBT, Captax, Dermacid. Physical Data: mp 180–182 °C; bp 305 ± 25 °C at 760 Torr. Solubility: not very soluble in ethanol diethyl ether, benzene, and carbon tetrachloride. Moderately soluble in acetone (10 g/100 mL) and glacial acetic acid. Soluble in alkaline solutions. Insoluble in H2O in its neutral form but freely soluble in its salt form. Form Supplied in: solid; widely available. Analysis of Reagent Purity: IR, NMR. Preparative Methods: benzothiazole-2-thiol can be synthesized by several methods. A commonly employed industrial method involves treating aniline with carbon disulfide (CS2) and sulfur under high temperatures and pressures (eq 1).1 Other methods include the condensation of 2-mercaptoaniline with CS2 or thiophosgene.2 Other syntheses describe the use 2-mercaptoaniline disulfide,3 2-chloro-benzothiazole,4 or benzothiazoline-2-thione.5 Benzothiazole-2-thiol can also be obtained from more elaborate precursors such as sulfenamide derivatives,6 β-keto analogs,7 or by reduction of bis(benzothiazole-2-yl) disulfide. (1) Purification: benzothiazole-2-thiol can be purified by heating in tert-butyl methyl ether at 70 °C for 30 min followed by filtration.8 Handling, Storage, and Precautions: apart from its odor, which may be considered unpleasant, the reagent can be used safely under normal laboratory conditions. Due to its widespread use in the rubber vulcanizing process, the compound is widely distributed. Toxicological studies indicate some occupational hazards and irritations from allergic reactions9 after prolonged contact with the skin. Sensitized subjects can rapidly develop irritations on contact with numerous rubber-containing, commonly-used articles such as gloves and tennis shoes. However, these irritations are most probably caused by the disulfide derivative (Altax) formed by oxidation of 2-mercaptobenzothiazole. Benzothiazole-2-thiol can also be found in the environment as a result essentially of its use in the rubber vulcanizing process.