Facile Heterolysis of a Carbon-Carbon Bond. Arylazodicyanomethanides as the Leaving Group Capable of Generating tert-Cumyl Cation and the Hydrogen-Bond-Insusceptible Behavior of the Leaving Group Anions

Article abstract of DOI:10.1021/ja00269a042

Decompositions of (p-nitrophenyl)azo-tert-cumylmalonitrile in polar solvents were found to proceed via the heterolysis of a carbon-carbon bond to generate tert-cumyl cation and the conjugate base of (p-nitrophenyl)hydrazonomalononitrile.The major products arising from tert-cumyl cation are as follows: tert-cumyl methyl ether in methanol, the N-cumylpyridinium hydrazonide in pyridine, and α-methylstyrene in Me2SO and in DMF.The reactions in MeCN and in acetone afford a rearranged product, N-(tert-cumyl)(p-nitrophenyl)hydrazonomalononitrile, which gradually undergoes heterolysis as well.Decompositions of the azo compound and the rearragend product are faster in Me2SO than in methanol, being in conflict with the usual trend of solvent-ionizing power.This phenomenon is explained in terms of extensive charge dispersal of the leaving group anion wich prevents hydrogen bonding with a protic solvent molecule.It is pointed out that the behavior of the conjugate base of (p-nitrophenyl)hydrazonomalononitrile as the leaving group anion is closely connected with the function of FCCP (the p-CF3O derivative of the hydrazone) as one of the best uncouplers of phosphorylation in mitochondrial systems.