GB1284669A - Sulfamoyl-1,3,4-thiadiazoles and their use as agricultural pesticides - Google Patents

Abstract

1284669 Sulphamoyl-1,3,4-thiadiazoles AIR PRODUCTS & CHEMICALS Inc 16 Oct 1970 [17 Oct 1969 2 Oct 1970] 49315/70 Heading C2C Novel 1,3,4,-thiadiazoles of the formula in which R 1 is hydrogen or a C 1-7 acyclic hydrocarbon radical optionally substituted by halogen, hydroxy, cyano or C 1-7 alkoxy groups, R 2 is as R 1 or a C 1-7 alkoxy group, R 3 is hydrogen or a C 1-7 acyclic hydrocarbon radical, R 4 is hydrogen, a C 1-7 acyclic hydrocarbon radical or a cycloalkyl group containing up to 7 carbon atoms, and R 5 is hydrogen, a cycloalkyl group containing up to 7 carbon atoms or a C 1-7 acyclic hydrocarbon radical optionally substituted by halogen, hydroxy, cyano or C 1-7 alkoxy groups, provided that R 1 and R 2 are not both hydrogen and R 4 and R 5 are not both hydrogen or cycloalkyl, and, when R 3 is hydrogen, the metal, ammonium and amine salts and the tautomers of the formula are prepared (i) by condensing sulphonyl chlorides of the formula with amines HNR 1 R 2 , (ii) reacting amines of the formula with (a) an isocyanate R 5 NCO, (b) a carbamoyl chloride ClCONR 4 R 5 or (c) phosgene and subsequently an amine R 4 R 5 NH, (iii) reacting an isocyanate of the formula with an amine R 4 R 5 NH and (iv) alkylating compounds in which R 3 is H, or the alkali metal salts thereof, with an alkyl halide R 3 X. Examples describe the preparation of a variety of 1,3,4-thiadiazoles. 2 - Amino - 1,3,4 - thiadiazole - 5 - N,N dimethylsulphonamide is obtained by acylating 2 - amino - 5 - mercapto - 1,3,4 - thiadiazole with acetic acid, treating the resulting 2-acetamido-5- mercapto - 1,3,4 - thiadiazole with Cl 2 in acetic acid to obtain 2-acetamido-5-chlorosulphonyl- 1,3,4-thiadiazole which is condensed with dimethylamine and the resulting 2-acetamido-5- N,N-dimethylsulphonamido-1,3,4-thiadiazole hydrolysed to the required amino compound. 1 - Methyl - 3 - (5 - chlorosulphonyl - 1,3,4 - thiadiazol-2-yl) urea is obtained by reacting 2- amino - 5 - mercapto - 1,3,4 - thiadiazole with methyl isocyanate and chlorinating the resulting 1 - methyl - 3 - (5 - mercapto - 1,3,4 - thiadiazol - 2- yl) urea. 1,3 - Dimethyl - 3 - (5 - chlorosulphonyl - 1,3,4 - thiadiazol - 2 - yl) urea is prepared by treating 5-methylamino-2-mercapto- 1,3,4-thiadiazole with NaOH/I 2 to obtain di-5- (2 - methylamino - 1,3,4 - thiadiazolyl) disulphide which is reacted with methylisocyanate and the resulting di - 5 - [1,3 - dimethyl - 3 - (1,3,4 - thiadiazol - 2 - yl)urea]disulphide treated with Cl 2 in acetic acid. The novel 1,3,4-thiadiazoles possess herbicidal properties and are used in conventional methods for pre- and post-emergence of weeds.