INVERSE PHASE-TRANSFER CATALYSIS - KINETICS AND MECHANISM OF THE PYRIDINE 1-OXIDE-CATALYZED SUBSTITUTION-REACTION OF BENZOYL CHLORIDE AND BENZOATE ION IN A 2-PHASE WATER DICHLOROMETHANE MEDIUM

The two-phase reaction of benzoyl chloride (PhCOCl) and benzoate ion with pyridine 1-oxide (PNO) as the inverse phase transfer catalyst yields both the substitution product (benzoic anhydride) and the hydrolysis product (benzoic acid). A high yield (> 95%) of benzoic anhydride can be obtained if a polar organic solvent like dichloromethane is used. Under appropriate conditions, this reaction follows the rate law -d[PhCOCl]org/dt = (k(h) + k(c)[PNO]iaq)[PhCOCl]org. The effects of agitation rate, organic solvent, ionic strength, temperature, and the concentrations of reactants and catalyst on the reaction rate were investigated. A mechanism to rationalize the kinetic results is also given.