Facile preparations of 4-fluororesorcinol

Abstract

Two facile methods for preparing 4-fluororesorcinol have been developed. In the first method, the direct fluorination of 1,3-dimethoxybenzene with trifluoromethyl hypofluorite carried out in Freon 11 at −78 °C afforded 2,4-dimethoxyfluorobenzene. Demethylation by heating under reflux in 48% HBr in acetic acid gave 4-fluororesorcinol in an overall yield of 60%. The second method involved the fluorination of 2,6-dimethoxyacetophenone by trifluoromethyl hypofluorite in Freon 11 at −78 °C, leading to 2,6-dimethoxy-3-fluoroacetophenone. On heating under reflux in 48% HBr in acetic acid, 4-fluororesorcinol was obtained in an overall yield of 74%. The latter is the method of choice for preparing 4-fluororesorcinol.