Reactions of N-halogenobenzylmethylamines with triethylamine in acetonitrile. Effect of leaving group upon the imine-forming transition state
Abstract
Reactions of N-halogenobenzylmethylamines (1) and (2) with Et3N–MeCN have been investigated kinetically. Eliminations from (1) and (2) were quantitative and regiospecific, producing only benzylidenemethylamines. For the elimination reaction of (1) with Et3N, kH/kD 5.7, p 0.88, ΔH‡ 9.1 kcal mol–1, and ΔS‡–42.4 cal mol–1K–1 were determined. The transition-state structure is assessed as being highly symmetric with similar extents of Cβ–H and Nα–Cl bond cleavage, little carbanionic character, and significant π-bond formation. The structure of the transition state changes only slightly with the change in the leaving group from Cl to Br.