GB895928A - A process for the preparation of 2,6-dialkyl phenols - Google Patents

Abstract

A process for the preparation of a 2,6-di-alkyl phenol unsubstituted in the 4 position comprises mixing an aluminium halide catalyst with a phenol having a replaceable hydrogen atom on the ring carbon atoms in the para and at least one of the ortho positions relative to the hydroxyl group, at a temperature of at least 130 DEG C., mixing the resulting mixture with a molar excess of a mono-olefin, heating the mixture of phenol, mono-olefin and catalyst under pressure and separaing the 2,6-dialkyl phenol from the reaction mixture. The product is preferably 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 concentrations of 2,6-dialkyl phenol, 4-alkyl phenol, 2,4-dialkyl phenol and 2,4,6-trialkyl phenol is a maximum and the time at which the concentration of the 2,6-dialkyl phenol in the reaction mixture is a maximum. The preferred reactants are phenol itself or phenol substituted by alkyl, halogen, amino or nitro groups and alkenes containing up to 10 carbon atoms or aryl olefins. The reaction is preferably carried out at 100 DEG C.-150 DEG C. in the absence of a molecular oxygen, water and iron and using a catalyst promotor, e.g. a halogen compound. In the example phenol is alkylated with isobutylene in the presence of aluminium chloride and tert. butyl chloride as promotor using various temperatures for the catalyst addition and the alkylation. Reference has been directed by the Comptroller to Specification 843,745.