THE RADICAL-ANION OF NAPHTHALENE AS PROMOTER OF THE SELECTIVE CATALYTIC DEHYDROGENATION OF 1,4-CYCLOHEXADIENE TO BENZENE AND OF THE ISOMERIZATION OF LINEAR 1,4-HEXADIENES TO 2,4-HEXADIENES

Two new examples of the application of the naphthalene radical anion, namely two cases of catalytic C-H bond activation, are described; viz.: (a) selective room temperature dehydrogenation of 1,4-cyclohexadiene to benzene, and (b) partial transformation of 1,4-hexadiene into its internal conjugated isomer. Radical anions derived from other bi- or tricyclic aromatics were tried in the reaction of the cyclic diene, and their behaviour found to depend to some extent on their reduction potentials. The use of a negatively charged electrode in place of the radical anion promoters was investigated, but no transformation of 1,4-cyclohexadiene was observed under the conditions of the electrochemical experiments. Careful GC analysis of the products from the isomerization reaction showed that no dihydronaphthalene was produced, thus excluding pathways initiated by action of the naphthalene radical anion as a base.