Kinetics of reactions of benzyl chloride/p-chlorobenzyl chloride with sodium sulfide: phase-transfer catalysis and the role of the Omega phase

Abstract

The reactions of benzyl chloride and p-chlorobenzyl chloride with sodium sulfide were carried out both in the solid-liquid and liquid-liquid modes with phase-transfer catalysis. Tetrabutylammonium bromide was found to be the most efficient catalyst for the system among six catalysts tried. In the solid-liquid mode, the reaction was found to be mass transfer controlled with an activation energy of 2.3 kcal/mol, whereas the liquid-liquid reaction was found to be kinetically controlled with an activation energy of 11.3 kcal/mol. The reactivities of benzyl chloride and p-chlorobenzyl chloride were compared under different controlling regimes. The effect of the Ω phase on the rate of solid-liquid reaction was also studied. A maximum rate enhancement by factors of 12 and 57 was obtained for benzyl chloride and p-chlorobenzyl chloride, respectively, with a calculated amount of water compared to no extra water. The importance of mass-transfer resistance was assessed at the maximum rate.