STUDY ON KINETICS OF THE PHASE-TRANSFER CARBONYLATION OF BENZYL CHLORIDE CATALYZED BY DICOBALT-OCTACARBONYL

Reaction kinetics of CO_2(CO)_8-catalyzed carbonylation of benzyl chloride was studied in a liquid-liquid two-phase system(water/p-xylene). The disappearance rate of benzyl chloride is found to fit a pseudo first order kinetics law when the carbon monoxide pressure is kept constant. The observed rate constant is directly proportional to the amount of Co_2(CO)_8, PhCH_2N~+(CH_3)_3Cl~- and NaOH. It is shown that the rate-limiting step is the cleavage of the acylcobalt carbonyl [PhCH_2COCo(CO)_4] by PhCH_2N~+(CH_3)_3OH~- at the liquid-liquid interface. According to the experimental kinetic results, the reaction mechanism is suggested and the reaction rate equation is derived.