Christian P. Meintzer

Polar radicals XVIII. On the mechanism of chlorination by N-Chloroamines: Intermolecular and intramolecular abstraction

Abstract The photochlorinations of the n -butyl, n -pentyl, and n -hexyltrimethyl-ammonium chlorides, using molecular chlorine in hexachloroacetone or 15% CD3CO2D/85% H2SO4, or using N-chlorodimethylamine in the acid solvent are described. The ammonium group exerted a strong polar directing effect upon the site of substitution. This effect was found to be more pronounced in the more polar protic solvent. The reagent, N-chlorodimethylamine, generated the dimethylamminium radical, whose reaction showed a polar sensitivity toward hydrogen abstraction similar to that of the chlorine atom, but exhibiting a much greater secondary/primary selectivity. Comparison of the isomer distributions obtained from the self photochlorination reactions of N-chloro- n -hexylmethylamine and N-chloro- n -pentylmethylamine in the acid solvent, with the distribution pattern obtained for the chlorinations of the ammonium salts with N-chlorodimethylamine, suggested that the self chlorinations of the N-chloroamines proceed by the intramolecular hydrogen abstraction mechanism suggested previously.