The herbicidal activity of 3‐substituted 1‐phenylureas

A variety of 1‐phenylureas, substituted in the 3‐position with one acyl, alkoxycarbonyl or cyano group, and optionally with a lower alkyl group, have been synthesised and assessed for pre‐ and post‐emergence herbicidal activity against a range of monocotyledonous and dicotyledonous weed species. Generally, activity was associated only with compounds containing two small substituents in the 3‐position. Their possible metabolic fate is discussed in the light of comparisons with the activity of the commercial herbicides, fenuron, monuron and diuron, and their de‐methylated derivatives.