Solid-liquid phase equilibrium in the water-Zn(II) methanesulfonate and water-Cu(II) methanesulfonate systems

Fragments of M(CH3SO3)2-H2O (M = Zn,Cu) phase diagrams from subsolidus temperatures up to 70 °C (343.15 K) were obtained. Melting parameters of anhydrous zinc methanesulfonate (Tm = 566.2 ± 0.3 K, ΔmH = 33.4 ± 0.6 kJ/mol) were clarified. New dodecahydrate zinc methanesulfonate and octahydrate copper methanesulfonate were revealed and characterized. Space group (R-3), lattice parameters (a = 9.1711(2), c = 21.4910(5)) and structure of Zn(CH3SO3)2∙12H2O were determined. The dodecahydrate melts congruently at Tm = 299.4 ± 0.1 K, with the enthalpy of fusion ΔmH = 78.9 ± 0.1 kJ/mol. The octahydrate Cu(CH3SO3)2∙8H2O melts incongruently at 254.9 ± 0.1 K.