Thermoanalytical and solution stability studies of hexamethylenedithiocarbamates

Abstract

Thermogravimetric and differential scanning calorimetric investigation of the thermal behavior of nickel(II), copper(II), zinc(II) and cadmium(II) hexamethylenedithiocarbamates were performed under nitrogen and air atmospheres in order to investigate the steps and products of thermal decomposition. When obtained in a crystalline form, the decomposition products were identified by their X-ray diffraction patterns. Metal sulfides and oxides were the major residues under nitrogen and air atmospheres, respectively. Spectrophotometric measurements in the ultraviolet region were used to estimate the pKa = 3.6 ± 0.2 for the haxamethylenedithiocarbamic acid at 0.50 mol dm -3 ionic strength (KCl) at 25.0°C and the kinetic parameters of decomposition at different pH values (klim = 2.21 × 10 -2 s-1 and t1/2 lim = 156 s). ©2006 Sociedade Brasileira de Química.