Thermal Decomposition and Hydrolysis of Dithionates of Metal(II) Amine Complexes

Abstract

Thermal decomposition under both dynamic temperature conditions and isothermal conditions at 235 and 240°C, and hydrolysis by using H₂SO₄, solution (0.4 25∼17.1 mol/kg-H₂O, 3 0-95°C)and NaOH solution (2.1 9∼12.0 m olfkg-H₂O, 140-150°C) of the complex salts [M^II ( amine)n ]. (M=Ni, Cu, Zn, Cd; amine=en, pn, dien; n=2, 3) were carried out. Sim ultaneous thermal decomposition to form SO₂ and amine occured for these complexes at 160-275°C. However, a part of amine also decomposed into black substances indistinguishable by prolonged heating. Decomposition of dithionate proceeded after neutralization of amine in acid solution. The rate of acid hydrolysis of dithionate ion was first order to the concentrations of h ydrogen ion and dithionate ion. On the other hand, alkali mole ratio more than 4 was n e eded to decompose dithionate ion perfectly in alkaline solution. The complex salts [Zn^II(amine)n]S₂O₆ evolved only amines without decomposing dithionate ion with alkali mole ratio less than 2.