GB795574A - Process for the alkylation of aromatic compounds - Google Patents

Abstract

Phenols, thiophenes and furans are alkylated with an olefine acting compound, using a preformed complex of boron trihalide and an iron group metal halide as a catalyst. The catalyst is preferably a preformed complex of boron trifluoride and an iron group metal halide in a low valence state, e.g. ferrous fluoride, cobaltous fluoride, or nickelous fluoride and may be supported on a porous carrier. The complex may be used either in lump form or as preformed pills. Suitable supporting materials are activated charcoal, petroleum coke, coconut char, bone char, metal halides or oxides and other unspecified metal compounds. Suitable phenols, thiophenes and furans which may be subjected to the alkylation are phenol, di and trihydric phenols, halophenols, nitro phenols, naphthol, guiacol, anol, eugenol, thymol; hydroxyacetophenones, hydroxydiphenyls, p-methoxy phenol, cyclohexylphenols, aminophenols, alkyl thiophenes, halo thiophenes, nitrothiophenes, cyanothiophenes, carboxythiophenes, alkyl furans, halofurans, nitrofurans, cyanofurans and carboxyfurans. Suitable olefine acting compounds are alkyl halides or alkyl phosphates which produce olefines under the conditions of the alkylation reaction, and gaseous or liquid olefines such as ethylene, butylene, isobutylenes, olefine polymers having from 6-18 carbon atoms per molecule, cyclopentene, methycyclohexene, butadiene, isoprene. The reaction is carried out at a temperature of from - 60 DEG C. to 300 DEG C. at pressures from about atmospheric pressure to about 100 atmospheres, preferably under sufficient pressure to maintain the reactants and the products in a substantially liquid phase and to maintain the complex as such that no boron trifluoride is lost therefrom. It is preferable to have present from 2 to 10 or more, sometimes up to 20 molecular proportions of alkylatable aromatic hydrocarbon per one molecular proportion of olefine acting compound present. The process may be carried out batchwise or continuously and the reactants added in various ways. Examples are given of the preparation of 2-amyl 5-methyl phenol, by the action of m-cresol with mixed amylenes, amylthiophene from thiophene and 2-pentene, tertiary butyl furan from furan and tertiary butyl chloride. The preparation of 2,6 di-tert.-butyl-4-methyl phenol by the alkylation of p-cresol with tert-butyl chloride or isobutylene is also mentioned.ALSO:Phenols, thiophenes and furans are alkylated with olefine acting compounds in presence of a preformed complex of boron trihalide and an iron group metal halide, preferably a complex of boron trifluoride and ferrous fluoride. The complex may be prepared by either reacting iron with hydrogen fluoride and reacting the ferrous fluoride so formed with boron trifluoride, or contacting the iron simultaneously with hydrogen fluoride and boron trifluoride. The addition of boron trifluoride should take place in an atmosphere of hydrogen fluoride and the iron should preferably be in the finely divided state. Suitable supports are activated charcoal, petroleum coke, coconut char, metal fluorides, e.g. aluminium fluoride, barium fluoride, calcium fluoride, magnesium fluoride, strontium fluoride or metal oxides.