Some chemical and physical properties of epronaz, a new herbicide

A brief account is given of the work leading up to the synthesis of epronaz (BTS 30 843), 1‐(N‐ethyl‐N‐propylcarbamoyl)‐3‐propylsulphonyl‐1,2,4‐triazole, a new pre‐ and early post‐emergence herbicide for annual grasses. The synthesis is described, together with the occurrence and isolation of all three possible positional isomers in the final (carbamoylation) stage. The evidence for the structure assigned to epronaz is presented together with that for the other two isomers, and their interconversion is described. Some chemical properties of epronaz are described, with particular reference to its hydrolysis and its ability to function as a carbamoylating agent, in relation to persistence in the environment and to mode of action respectively. Some physical properties are also reported, including vapour pressure, solubility, and spectra. The mass spectral fragmentation pattern is also discussed.