Herbicidal 2-fluoro-3,5-dihalo-4-hydroxy-pyridines (derivs) - esp against perennial weeds, eg couch grass

摘要

The novel title cpds. are of formula (I): (where X1 and X2 are Br, Cl, F or I, and R is H, a cation forming a salt, aryl, acyl or 1-6 C alkyl substd. by OH, 1-6 C alkoxy, aryl or 2-6 C alkenyl or alkynyl). They are applied at the rate of 0.5-10 kg/ha. and may be prepd. by several methods, e.g. halogenation of 2-fluoro-4-hydroxypyridine opt. followed by acylation or alkylation.