Novel Alkylanthracenes Synthesis, Reductive Alkylation, and Reductive Polymerization

A series of novel substituted anthracenes has been prepared which carry two or four n‐alkyl groups at C‐2 and C‐3 (C‐6 and C‐7). The route taken includes the synthesis of novel 2,3‐dialkylbutadienes, their Diels‐Alder reaction with 1,4‐benzo‐ or 1,4‐naphthoquinone, the dehydrogenation of the adducts, and the reduction of the anthraquinones. The substituted anthracenes are submitted to reduction and reductive alkylation in ethereal solvents and in liquid ammonia to yield 9,10‐dialkyl‐substituted 9,10‐dihydroanthracenes. A modification of the reductive alkylation, i.e. the introduction of 1,n‐dihaloalkanes as electrophiles, provides polymeric chains, in which dihydroanthracene moieties are linked by alkanediyl bridges. It appears that the behavior of alkyl‐substituted anthracenes in reductive alkylation and reductive polymerization reactions is completely different to that of the parent anthracene. This feature, which follows from different solubilities and basicities of carbanionic intermediates in the solvent systems, allows to control the properties of the polymer chains.