GB794153A - Process for alkylating aromatic compounds - Google Patents

Abstract

Aromatic hydrocarbons, and their hydroxy-and halo-derivatives, are alkylated with olefines or alkyl halides in the presence of anhydrous hydrogen fluoride and a preformed complex of boron trifluoride and an iron group metal fluoride. Preferred aromatic compounds are monocyclic such as benzene, toluene, xylenes, ethylbenzene, mesitylene, ethyltoluenes, n-propyl benzene, cumene, C6-C18 alkyl benzenes and toluenes, styrene, vinyl toluenes, allyl benzene, phenol, cresols, chlorophenols, p-bromophenol, 2,4,6-trichloro- and -tribromophenols, guaiacol, and, isoeugenol, eugenol, carvacrol, thymol, o- and p-cyclohexyl phenols, catechol, resorcinol, hydroquinone, pyrogallol, hydroxyhydroquinone, phloroglucinol, fluoro-, chloro-, bromo- and iod0-benzenes, chloro- and bromo - toluenes, p - dichloro, 1,2,4 - trichloro -, 1,2,3,4 - tetrachloro - and 1,2,4,5 - tetrachlorobenzenes, p - dibromobenzene, o- and p-bromochlorobenzenes, o-, and p-bromoiodobenzenes and p - chloroiodobenzene. Polycyclic compounds which may be used include diphenyl, diphenylmethane, triphenylmethane, fluorene, stilbene, naphthalene, anthracene, phenanthrene, naphthacene, rubrene and 2,21- and 4,41-dihydroxy-diphenyl. Olefines which may be used as alkylating agents include ethylene, propylene, 1- and 2-butenes, isobutylene, pentenes, olefine polymers of 6-18 carbon atoms, cyclopentane, cyclohexene, methylcyclopentene, methylcyclohexene, butadiene and isoprene, n-Butyl chloride is also referred to as an alkylating agent. The complex of the catalyst is preferably formed from an iron-group metal in the divalent state and can be prepared by forming the metal fluoride and adding the boron trifluoride in the presence of hydrogen fluoride; the metal fluoride may be formed in situ from the metal and hydrogen fluoride. It may be used in solution in HF when it should be present in an amount of at least one mol. per 150 mols. of HF, as a solid mass or slurry with HF when the HF should be present in an amount of at least 0.5 mol. per mol. of complex, or disposed on a carrier such as activated charcoal, aluminium fluoride, calcium fluoride, magnesium fluoride, strontium fluoride or barium fluoride, when the HF should be present in an amount of at least 0.01 mol. per mol. of complex. The hydrogen fluoride may be replaced by a C2-C6 alkyl fluoride which releases hydrogen fluoride under the reaction conditions. Liquid phase conditions are preferred at -60 DEG to 300 DEG C. The pressure should be sufficient to prevent the complex losing BF3 and may be 1-100 atmospheres. A mol. ratio of alkylating agent to aromatic compound in the range of 1 : 2 to 1 : 20 is preferred. Batch or continuous operations may be used. The examples describe the preparation of a FeF2.BF3 complex and its use with hydrogen fluoride in reactions between (1) propylene and toluene; (2) ethylene and benzene; (3) n-butyl chloride and m-cresol; (4) a propylene tetramer fraction and benzene.