GB843745A - Process for the preparation of 2, 6-dialkyl phenols - Google Patents

Abstract

A 2,6-dialkyl phenol product is prepared by heating a mixture of a hydroxy benzene compound having a replacable hydrogen atom on the carbon atoms in the para. and at least one of the ortho positions relative to the hydroxyl group and a molecular excess of a monoolefin under pressure in intimate contact with an aluminium halide catalyst, and the 2,6-dialkyl phenol is separated from the reaction mixture between the time at which the ratio of the molar concentration of the 2,6-dialkyl phenol to the sum of the molar concentration of 2,6-dialkyl phenol, 4-alkyl phenol, 2,4-dialkyl phenol and 2,4,6-trialkyl phenol reaches a maximum, and the time at which the concentration of 2,6-dialkyl phenol in the reaction mixture reaches a maximum. The alkylation may be carried out batchwise or continuously, preferably at 100 DEG -200 DEG C. and 7 to 70 atmospheres pressure in an inert atmosphere using an aluminium chloride catalyst which may be promoted by a hydrogen halide or saturated organic halide. The starting olefin is preferably an acyclic compound containing 4 to 7 carbon atoms e.g. isobutylene or an aryl olefin e.g. a -methyl styrene. The phenolic reactant may contain substituents such as methyl, ethyl, nitro or amino groups or bromine atoms in one or both of the meta positions on the ring. In an example phenol is alkylated with isobutylene, and the reaction conditions and the concentrations of the various reaction products after various reaction times are tabulated.