Studies in fungitoxicity. VI.—Fungicidal activity of certain 2‐(substituted thio)‐5‐(2,4‐dinitrophenylthio)‐1,3,4‐thiadiazoles and related compounds

Twenty 2‐(substituted thio)‐5‐(2,4‐dinitrophenylthio)‐1,3,4‐thiadiazoles and several related compounds were synthesised from the appropriate 1,3,4‐thiadiazole derivatives and the aryl chlorides, and tested for activity against Venturia inaequalis, Botrytis cinerea, Fusarium bulbigenum and Cercospora melonis. Only compounds derived from fungitoxic aryl chlorides were themselves fungitoxic. The compounds cleave at the Ph‐S bond. It is tentatively assumed that compounds in which this bond is not shielded may undergo a nucleophilic attack by cell constituents. This is paralleled by results obtained with dimethyldithiocarbamoyl derivatives where only those that readily split off the dimethyldithiocarbamate group had high activity against Venturia inaequalis .