The distribution and dissociation equilibria of phase-transfer catalyst tricaprylmethylammonium chloride and its aqueous-phase mass transfer.

Abstract

The distribution and dissociation equilibria of a representative phase-transfer catalyst, tricaprylmethylammonium chloride (Aliquat 336; Q+Cl–), were measured for the systems of n-butyl acetate–water, toluene–water, n-butyl acetate–aqueous NaCl solutions and toluene–aqueous NaOH solutions. The evaluated distribution coefficients of Q+Cl– and the OH–-substituted derivative (Q+OH–) were correlated as a function of the ionic concentrations in the aqueous phases. The dissociation constants of Q+Cl– and Q+OH– in the aqueous phase could be regarded as being identical.The diffusivities of Q+Cl– in water and in n-butyl acetate, and the ionic diffusivity of Q+ in the aqueous phase were measured. The aqueous-phase mass transfer of Q+Cl– could be quantitatively explained as that with an instantaneous reversible dissociation reaction.