GB786668A - Production of polyalkyl benzenes - Google Patents

Abstract

Alkyl benzenes having at least 3 alkyl groups are produced by condensing an aromatic hydrocarbon feed having at least 2 alkyl groups per molecule and having at least one unsubstituted nuclear hydrogen atom per molecule with formaldehyde to form a di-arylmethane, subjecting the diarylmethane to hydrogenolysis (i.e. the cleavage of a carbon to carbon bond accompanied by the addition of hydrogen) to produce alkyl benzenes and separating the product of hydrogenolysis to recover an alkyl benzene having one more alkyl group substituted on the nucleus than the aromatic hydrocarbon feed. The condensation is preferably catalysed by sulphuric acid optionally in the presence of methanol, ethanol, or glacial acetic acid. Alternatively, phosphoric acid trichloracetic acid, ferric chloride, methane sulphonic acid or hydrofluoric acid may be used, condensation being effected at 30-300 DEG F. The hydrogenolysis is preferably conducted at 650-900 DEG F. at a pressure ranging from atmospheric to 250 p.s.i.g. and may be catalysed by metals, oxides and sulphides of Group VI (b) VII (b) and VIII of the Periodic Table, molybdenum oxide on alumina being especially suitable. In examples, the process is directed particularly to the production of nearly pure pseudocumene by condensing any one of the xylene isomers or a mixture thereof with formaldehyde to produce a di-xylyl methane which is reacted with hydrogen to produce 1 molecule of xylene and 1 molecule of over 90 per cent 1,2,4-trimethylbenzene. Durene may be produced by an extension of the process.