Dehalogenation of polyhalophenols to 5-or 3,5-dihalophenols - by hydrogenation in the presence of iron nickel or cobalt sulphides or noble metals and S cpds

摘要

Starting materials are cpds. (I):- (where X is halogen; R1-R4 are H, halogen, alkyl, aralkyl aryl alkoxy, aryloxy, alkylthio or dialkylaminomethyl at least one of R1, R2 and R4 being halogen and R3 may be OH or halogen, R is OH or R + R1 is OCH2OCH2 when R is considered as the phenolic oxygen and X, R2, R3 and R4 are H, halogen, or alkyl, one of X and R3 and R2 and R4 being halogen) the reaction is effected at 100-350 degrees C under 20-250 ats (relative).