Studies on Metal Hydroxy Compounds. XIV. Thermal Analyses, Calorimetry, and Decomposition Kinetics of Heterocationic Hydroxy Chloride Compounds

Abstract

Studies were carried out on two series of mixed metal hydroxy chloride compounds of the type xMe(OH)2•yMCl2 where Me = Cd, Cu and M = Mn, Co, Ni, Cu, Zn, Cd, Mg, or Ca.Thermal analyses for the Cd–M series reveal that the initial mode of decomposition involves a dehydroxylation step with a concomitant metathetical reaction between MCl2 and CdO. The compound CdCl2•2CdO is formed and decomposes at higher temperature leading to the eventual volatilization of CdCl2. The kinetics of thermal decomposition follow a simple first-order rate equation. The sole exception to this general pattern of behavior is the Cd–Zn compound.The initial mode of thermal decomposition of the Cu–M series compounds follows a parallel pattern described for the Cd–M series. The kinetic data for the Cu–M series are fitted into three groups: (i) phase boundary control embracing the contracting sphere and contracting plate model equations, (ii) A-E type equation with n = 2, and (iii) first-order rate equation.