Solvent-free reactions of fullerenes and N-alkylglycines with and without aldehydes under high-speed vibration milling

Abstract

The solvent-free reactions of fullerenes and N-alkylglycines with and without aldehydes (RCHO) 2a– e under high-speed vibration milling (HSVM) conditions have been investigated. Fulleropyrrolidines 4a– e (C 60(CH 2N(CH 3)CHR), R=H ( 4a ), C 6H 5 ( 4b ), p-NO 2–C 6H 4 ( 4c ), p-CH 3O–C 6H 4 ( 4d ), p-(CH 3) 2N–C 6H 4 ( 4e )) were obtained in moderate yields from reactions of C 60 with aldehydes 2a– e and N-methylglycine (Prato reaction). In all these solvent-free reactions, 4a was found to be formed besides 4b– e , indicating that fullerenes can react with N-substituted glycines in the absence of aldehyde to give fulleropyrrolidines. For this novel reaction, a possible reaction mechanism involving an electron transfer process has been proposed. Intrigued by this observation, the dependence of the yield on the reagent ratio for the reaction of C 60 with paraformaldehyde and/or N-methylglycine was examined to search the optimal conditions. The reaction of C 70 with paraformaldehyde and/or N-methylglycine under HSVM conditions was also studied and was found to give the positional isomers of [70]fulleropyrrolidines.