Synthesis of 4-(ω-X-alkyl)benzonitriles (X = 1,3-dioxan-2-yl, CN, CO2Et) by the reaction of terephthalonitrile dianion with ω-X-alkyl bromides in liquid ammonia

Resumo

The main products of the reaction of terephthalonitrile dianion disodium salt with ω-X-alkyl bromides (2-(2-bromoethyl)-1,3-dioxane, 5-bromovaleronitrile, ethyl 6-bromohexanoate) in liquid ammonia are the corresponding 4-(ω-X-alkyl)benzonitriles. Similar reactions of benzonitrile radical anion sodium salt lead to ω-X-alkylbenzenes. In both cases the formation of products is due to selective ipso-alkylation of anionic forms that indicates the nucleophilic activity of terephthalonitrile dianion and benzonitrile radical anion in these reactions and the realization of alkylation via S_N2 mechanism.