The Electrochemical Fluorination of N, N-Dimethylalkylamines and N, N-Dialkylmethylamines

Abstract

Electrochemical fluorination of N, N-dimethylakylamines [(CH₃)₂NR; R=C₂H₅ n-C₃H₇, n-C₄H₉, n-O₅H₁₁, t-C₄H₉, c-O₅H₉ and c-C₆H₁₁] and N, N-dialkylmeth ylamines [R₁R₂⋅NCH₃; R₁=R₂=C₂H₅, R₁=R₂=n-C₃H₇, R₁=R₂=n-C₄H₉;R₁=n-C₃H₇, R₂=n-C₄H₉ and R₁ n-C₃H₇, R₂ =n-C₅H₁₁] was carried out.
In the case of N, N-dimethylalkyl amines, yields of perfluoroamines decreased with the increase in the number of carbon atoms of the straight-chain alkyl group due to the cleavage of C-N bond. Isomerization and ring-opening reaction occurred extensively for amines with branched and cycloalkyl groups, respectively.
In the case of N, N-dialkylmethylami nes, it was found that the initial concentration of the amine in anhydrous hydrogen fluoride has great influence upon the yield of the fluorinated amine, which was not the case with N, N-dimethylalkylamines: The higher concentration gave the better results. The β-scission of an alkyl group of amines resulted in the formation of a considerable amount of perfluoro(N, N-dimethylalkylamine). The longer alkyl group in an asymmetric N, N-dialkylmethylamine showed a tendency of such β-scission more easily.