Electrochemical fluorination of aliphatic secondary amines

Electrochemical fluorination (ECF) has been examined for six aliphatic seco ndary amines: N,N-di-ethylamine, N-ethyl,N-n-propylamine, N,N-di-n-propylam ine, N-ethyl,N-iso-propylamine, N,N-di-iso-propylamine, and N-methyl,N-n-bu tylamine. It was found from these amines that not only the corresponding F- (N-fluoro-N,N-dialkylamines) but also F-imines having the same number of th e carbon atoms were formed in low yields. The suppression of the C-N bond c leavage (blocking effect) which is expected to occur during fluorination du e to the presence of bulky N-alkyl group was not observed as a result of th e ECF of these aliphatic secondary amines. It was also found that the chang e of the initial solute concentration of N,N-di-n-propylamine did not affec t on the product yields, which is usually observed for cyclic secondary ami nes. Several F-(N-fluoro-N,N-dialkylamines) were treated with triphenylphos phine for conversion into the corresponding F-imines. An imine bond was gen erated during this defluorination exclusively at the site of the alkyl grou p with a longer chain length when there were two different alkyl groups pre sent in F-(N-fluoro-dialkylamines). (C) 2000 Elsevier Science S.A. All righ ts reserved.