CHEMICAL-STRUCTURE OF COALS AS INDICATED BY REDUCTIVE ALKYLATION

Reduction with potassium in tetrahydrofuran in the presence of naphthalene, and alkylation of the 'coal anion', were applied to coals of different rank. The reduction reaction alone increases the dissolution of the coals in benzene only to a very small extent. However, the reduction process in conjunction with alkylation of the 'coal anion' leads to products readily soluble in benzene. The solubilization of alkylated coals depends on the type of coal, the degree of its substitution with alkyl groups, and the length of the substituent alkyl chain. The number-average molecular weights of benzene extracts from the lowest-rank coal ranged from 500 to 800, whereas the higher-rank coals consist essentially of structural units characterized by number-average molecular weights ranging from 1300 to 2000. © 1979.