In this study the rate constants and the activation energies of the direct quaternizations of the tertiary amines with benzyl chloride are obtained. The reactivities are in the order (CH3)3N > (C2H5)3N > (C4H9)3N > (C3H7)3N > (C8H17)3N > (C6H13)3N > pyridine > N,N-dimethylaniline almost-equal-to quinoline. Owing to the steric effect of the ethyl group, the rate constant of (CH3)3N is about 100 times that of (C2H5)3N and, owing to the polar, the steric and the resonance effects of the phenyl group, the rate constant of (CH3)3N is about 3000 times that of NN-dimethylaniline. The rate constants of other trialkylamines are of the same order, because their polar effects and steric effects are approximately counterbalanced. The range of the activation energies of the quaternization of trialkylamines is from 9.94 to 12.0 kcal mol-1, and that of the heterocyclic amines and NN-dimethylaniline is from 13.2 to 15.6 kcal mol-1. The rate of the quaternization of trimethylamine is greatly reduced by adding benzene or hexane, and log k2 increases linearly with increasing volume average solubility parameter of the mixed solvent, and the direct quaternization rate constant is obtained by extrapolation. For convenient comparison, relevant kinetic data from the literature and those obtained in this study are separately listed in tables. They show that the spread of the kinetic data of this work is reasonable.
關聯:
CHEMICAL ENGINEERING JOURNAL AND THE BIOCHEMICAL ENGINEERING JOURNAL
