GB616829A - Improvements in and relating to the production of alkyl phenols - Google Patents

Abstract

Phenol is butylated with isobutene in the presence of sulphuric acid at a temperature not exceeding 70 DEG C. and the reaction products are then isomerized to yield p-tertiary butyl phenol by heating at a higher temperature less than 150 DEG C. The sulphuric acid acts as a catalyst and should preferably be not more than 5 per cent by weight of the weight of phenol used. p-Tertiary-butyl-phenol formed may be isolated by any convenient means, but more particularly by (a) cooling the reaction product to about 15 DEG C., separating off the solid by filtering or centrifuging, neutralizing excess acid in the solid and fractionally distilling the neutral solid to give the pure phenol, or by (b) neutralizing the final reaction products, cooling, separating the solid product by filtering or centrifuging and purifying by distillation. The process may be made continuous by returning the mother liquors obtained after the separation of the solid product back to the butylation stage. A temperature range of 30-70 DEG C. is preferred for butylation and of 100-150 DEG C. for isomerization. The isobutene used may be admixed with other paraffin hydrocarbons or butenes. In an example, phenol in the presence of sulphuric acid is treated at a temperature of 60-70 DEG C. with a gas containing on a percentage molar basis 18 per cent of isobutene, 7 per cent of normal butene and 75 per cent of butenes until the increase in weight corresponds to the absorption of four gram-molecules of isobutene. The product is heated for two hours at 150 DEG C. and after cooling is centrifuged to separate solid p - tertiary - butyl - phenol, the mother liquor being returned to the butylation step together with further quantities of phenol and sulphuric acid. This latter mixture is again butylated and the p-tertiary-butyl-phenol separated as above described. This cycle of operations is repeated thirteen times, the p-tertiary-butyl-phenol obtained being purified by distillation after treatment with an aqueous solution of sodium carbonate.