Reactivities of triarylmethyl and diarylmethyl cations with azide ion investigated by laser flash photolysis. Diffusion-controlled reactions

Abstract

By use of the technique of laser flash photolysis, rate constants k AZ and k S have been directly measured for the reactions at 20 o C in acetonitrile-water (AN-W) solutions of varying composition of 18 triarylmethyl and 10 diarylmethyl cations with azide and solvent. The cations have k S that depend on substituent and vary from ∼10 1 to ∼10 7 s −1 . For the more stable ions k AZ also varies, increasing with decreased electron donation and also increasing by as much as 10 3 with increasing acetonitrile content. For less stable cations, however, the rate constant becomes independent of substituent