4-SUBSTITUTED 2-AMINO-1,3,4-THIADIAZOLONES-(5) AND THEIR USE AS HERBICIDES

1,267,290. 2 - Amino - 1,3,4 - thiadiazolones. FARBENFABRIKEN BAYER A.G. 23 Oct., 1970 [25 Oct., 1969], No. 50474/70. Heading C2C. Novel thiadiazolones of the formula in which R represents alkyl or alkenyl groups having 1-8 carbon atoms and optionally substituted by alkoxy, cycloalkyl, cycloalkenyl, furyl or aryl group which aryl group may be substituted by halogen, alkyl, dialkylamino, alkoxy and/or haloalkyl, or R represents a C 3-12 cycloalkyl group or a anaryl group optionally substituted by alkyl, haloalkyl, nitro and/or alkoxy groups, and the known compound in which R is phenyl, are prepared by condensing a thiosemicarbazide of the formula R-NH-NH-CS-NH 2 with phosgene, preferably at temperatures in the range 25-100‹ C. in the presence of water. The reaction medium may also contain a water immiscible organic solvent. Examples relate to the preparation of the 4-phenyl, cyclohexyl, propyl, ethyl, isopropyl, butyl, benzyl and 41-chlorobenzyl compounds; many other suitable starting thiosemicarbazides are specified. 1-Cyclohexylthiosemicarbazide is obtained by NaBH 4 reduction of cyclohexanone thiosemicarbazone. The thiadiazolones possess herbicidal properties and are used in conventional forms as pre- and post-emergence weed-killers.