Methylation of Phenol over Alumina in the Vapour Phase : Influence of Copper Sulphate

A. C. College of Technology, Anna University, Gnindy, Madras-600 025

Manuscript received 17 March 1980, revised 21 January 1982, accepted 25 August 1982

Phenol is methylated using methanol over alumina and alumina impregnated with varying amounts of copper sulphate at 360, 400 and 440°, at a molar ratio of 0.75 : 1 of phenol to methanol. Over alumina, phenol undergoes direct nuclear (carbon) tnethylation, giving cresols and xylenois. Alumina with 10 and 20% copper sulphate catalyses both carbon and oxygen methylation forming cresols and anisole, respec­tively. Xylenois, which were absent over the above two catalysts, appear when the copper sulphate concentration increases to 30%. Further increase of copper sulphate from 30 to 40% not only enhances the proportion of xylenols in the products by increasing the temperature and the contact time, but also decreases that of anisole under these conditions. However, the concentration of cresols seems to be unaffected. Methylation of phenol follows a first order kinetics irrespective of the concentration of copper sulphate in the catalysts.