COAL SOLUBILIZATION - PROMOTION OF THE C-ALKYLATION REACTION BY NORMAL-BUTYLLITHIUM AND POTASSIUM TERT-BUTOXIDE

A new base-catalyzed C-alkylation reaction that employs a mixture of n-butyllithium and potassium tert-butoxide in refluxing heptane to produce coal anions that are subsequently treated with n-alkyl halides at 0 °C has been developed and applied. Almost quantitative pyridine solubilization was achieved by C-octylation of a Lower Kittanning coal, PSOC 1197. C-Octylation was less successful for the solubilization of bituminous Illinois No. 6 coal, APCSP 3, and subbituminous Wyodak coal, APCSP 2, which gave 35 and 33% soluble material, respectively. Their O-methyl derivatives yielded 43 and 20% soluble material in the same reaction. The observations are in accord with the concept of Ouchi and his associates that higher rank coals, although more aromatic in character, have a lower degree of polymerization than low-rank coals. In this situation relatively mild chemical reactions, such as C-alkylation, that lead to modest changes in molecular dimensions can disrupt intermolecular forces and accomplish solubilization of the high-rank coals. © 1990, American Chemical Society. All rights reserved.