COMPARISON OF CALCULATED EQUILIBRIUM MIXTURES OF ALKYLNAPHTHALENES AND ALKYLPHENANTHRENES WITH EXPERIMENTAL AND SEDIMENTARY DATA - THE IMPORTANCE OF ENTROPY CALCULATIONS

Evaluation of the relative stabilities of tetramethylnaphthalenes and dimethylphenanthrenes by means of molecular mechanics calculations all ows one to predict the equilibrium mixture compositions for these grou ps of compounds. These equilibrium compositions have been calculated a t various temperatures with and without taking into account the entrop y of the compounds. Comparison with experimental observations, and sed imentary data, showed that when entropy is taken into account in the c alculations, agreement between the experimental and sedimentary data i s much improved. A distinct temperature dependence of the equilibrium composition is predicted for the tetramethylnaphthalenes, indicating t he potential of this group of compounds for burial temperature evaluat ions. (C) 1997 Elsevier Science Ltd.