Triphase catalysis. I. Kinetics and mechanism of alkylation of phenylacetonitrile with alkyl halides catalyzed by aqueous naoh and polymer‐supported benzyltriethylammonium chloride

Abstract

AbstractThe alkylation and cycloalkylation of phenylacetonitrile (PAN) with excess of 1‐bromobutane and 1,4‐dibromobutane respectively catalyzed by aqueous NaOH and insoluble polystyrene‐bound benzyltriethylammonium chloride were studied and the rates depend upon several experimental parameters. The rate of cycloalkylation of PAN is five times faster than the alkylation and the former proceeds even in the absence of the solid catalyst. Both alkylation and cycloalkylation gave higher rates in reverse addition method than in direct addition. Deprotonation of PAN by hydroxide ion takes place without participation of the polymeric catalyst. The electrostatic force between the positive charge on the nitrogen atom of catalyst and carbanion is responsible for alkylation of active nitrile with polystyrene‐bound phase‐transfer catalyst. The rates of both the reactions increase with increased stirring speed, ring substitution, hydroxide ion concentration and catalyst amount and decrease with increased particle size and the degree of cross‐linking of the polymer. Apparent activation energies for the reactions were calculated. The kinetic results are discussed in terms of mass transfer and a combination of intraparticle diffusion and intrinsic reactivity limitations of the rates.