TX-100 reverse micelles as microreactors for alkaline hydrolysis of tris(2,2ʹ-bipyridine) iron(II) complex

Abstract

Alkaline hydrolysis reaction of tris(2,2ʹ-bipyridine)iron(II) complex with sodium hydroxide has been investigated in TX-100 reverse micelles using cyclohexane/water with hexanol as cosurfactant by spectrophotometric method. In reverse micellar medium, the reaction is first order with respect to each reactant. The effects of water pool size and surfactant concentration are investigated. The rate decreases as the [water]/[surfactant] molar ratio (W) increases, but increases as surfactant concentration increases. Effect of both W and surfactant concentration are prominent at lower regions of W. The results are explained by considering the occurrence of two reactions at a measurable speed in reverse micellar medium, i.e., aqueous dissociation and alkaline hydrolysis reactions. Both these reactions in the reverse micellar medium are catalyzed. In the water pool, properties of water are such that at lower W, dissociation reaction is favorable, whereas at higher W, hydrolysis is favorable. Experimental results also conclude that dissociation occurs mainly at the interface and hydrolysis in the cavity of the water pool.