GB567353A - Improvements in the manufacture of tetrazole compounds - Google Patents

Abstract

1.2.3.4-Tetrazole compounds, containing a substituted or unsubstituted hydrocarbon group in the 1-position and a mercapto group in the 5-position and tautomers thereof, are made, in the form of their alkali metal salts, by reaction of a compound of the formula R.NH.CSSR1, where R and R1 represent substituted or unsubstituted hydrocarbon groups, with an alkali metal azide. The free tetrazoles are obtained by acidification of the alkali-metal salts in solution. The mercaptan R1SH, split off during the reaction, constitutes a valuable by-product. In examples: 1-methyl-, phenyl-, cyclohexanyl-, (21 - methoxy) - phenyl-, (41 - chloro) phenyl-, benzyl- and a - and b -naphthyl-5-mercapto-1.2.3.4-tetrazoles are made from the corresponding N-substituted dithiocarbamic acid methyl esters and sodium azide in an aqueous ethyl alcohol medium with subsequent acidification. Any other substantially inert solvent or solvent mixture may be used. Other specified groups, R, are ethyl or higher alkyl, naphthylmethyl, diphenyl and cyclopentanyl and other substituents which such groups may carry are halogen atoms, nitro, amino, substituted amino, hydroxy, alkoxy and hydroxyalkyl groups. Also the group R may carry a second -NH.CSSR1 group, whereupon bis-tetrazole compounds are formed. Thiocarbamic esters of the above general formula are prepared by reaction of an amine of the formula R.NH2 with carbon disulphide in the presence of a strong base, e.g. caustic soda, to give, e.g. a compound R.NH.CSSNa, and treating this with an ester, R1X, where X represents the residue of a strong acid, e.g. a mineral acid or p-toluene sulphonic acid. Where a diamine such as p-phenylene diamine or benzidine is used, the product contains two -NH.CSSR1 groups. Thus, N-cyclohexanyl dithiocarbamic acid methyl ester is prepared from cyclohexylamine, carbon disulphide, caustic soda and dimethyl sulphate.