Improvements in or relating to the ethylation of toluene

摘要

Ethyl toluenes are prepared by (a) reacting toluene with 0.4-1.1 mol. of ethylene in the presence of aluminium chloride at 50-90 DEG C., (b) fractionating the product from (a) to obtain toluene, ethyltoluenes and diethyltoluenes, (c) disproportionating the diethyltoluenes from (b) in the presence of toluene and aluminium chloride at not more than 90 DEG C., (d) fractionating the product from (c) to obtain toluene, ethyltoluenes and diethyltoluenes and (e) combining the ethyltoluenes from (b) and (d) to obtain over head a fraction containing at least 30% of para isomer; the amount of aluminium chloride used in steps (a) and (c) being 0.5-3.5% by weight of total hydrocarbon. The bottoms from step (e) contain a high proportion of ortho-isomer and may be isomerized in the presence of aluminium chloride at nor more than 90 DEG C., ethyltoluenes separated from any toluene and diethyltoluenes formed and redistilled in step (e). Iso- and tere-phthalic acids may be prepared by oxidation of the overhead mixture of paraand meta-ethyltoluenes from the final fractionation. Oxidation may be effected with air in the presence of acetic acid as liquid diluent, and a mixture of manganese acetate, cobalt naphthenate, and ammonium bromide, as catalyst. Specification 752,200 is referred to.