NMR-STUDY ON THE ELECTROCHEMICALLY GENERATED TRIPHENYLMETHYL ANION

The C-13 and H-1 NMR spectra of the triphenylmethyl anion, which had b een generated by an electrochemical reduction of triphenylmethane in d imethylformamide at -40 degrees C, were successfully obtained. An anio n having a tetrabutylammonium counter cation had C-13 chemical shifts similar to those for an anion with a lithium counter cation. An examin ation of the H-1 NMR spectra revealed that the reaction is a one-elect ron reaction. Experiments conducted under temperature control showed t hat the anion is fairly stable below -20 degrees C. Decomposition of t he anion above -20 degrees C was suggested to be hydrogen abstraction from the beta-position of a tetrabutylammonium cation by a triphenylme thyl anion (Hofmann decomposition of the ammonium cation).