Coal chemistry. 8. Reactions of tetralin with coal and with some carbon-14-containing model compounds

When coal was treated with tetralin-l-14C at 4000C, small yields of α- and β-methylnaphthalenes-14C were observed. In order to determine the mechanism of the reaction, tetralin was heated with 14C-labeled 1,3-diphenylpropanes (1), with 1,3-diphenylpropene (2), and with 14C-labeled phenetoles (3). In each case methylnaphthalenes were observed, and the origins of the methyl groups were determined with carbon-14. In addition to the methylnaphthalenes, 1 and 2 also yielded toluene and ethylbenzene (after 19 h), whereas phenetole-β-14C (3-β-14C) yielded toluene (unlabeled) plus ethyl-14C-benzene, benzene, phenol, and a mixture of α- and β-ethyl-14C-naphthalenes. Crossover experiments with labeled phenetole and unlabeled ethyl p-tolyl ether proved the intramolecularity of the reaction phenetole → toluene + ethylbenzene, thus illustrating a 1,2-phenyl shift from oxygen to carbon