The synthesis of alkyl aromatic hydrocarbons and its geochemical implications

Abstract

In the present study clay minerals have been shown to catalyse alkylation at 200–270°C of substituted benzenes and naphthalenes by alcohols and esters that are known to occur naturally in sediments. It has also been demonstrated that the formation of CC and CO bond linkages under these experimental conditions is accompanied by some dealkylation of alkyl aromatic products. It therefore seems likely that alkyl aromatic compounds may be synthesized during the thermal treatment of coal. Consequently the significance, in relation to coal structure, of the occurrence of such compounds in the products of coal liquefaction, in artificial maturation experiments and in situations where pyrolytic analytical techniques are used requires re-examination. The value of alkyl aromatics as biomarkers for sedimentary maturation processes is questionable when thermal processes have been used in their separation and identification.