Study on Thermodynamic Properties of Ionic Liquid 1-Ethyl-3-methylimidazolium Alanine

We synthesized the alanine-based ionic liquid [C(2)rnim][Ala] (1-ethyl-3-methylimidazolium alanine) by using the neutralization method and characterized it. Using a solution-reaction isoperibol calorimeter, we determined the molar enthalpies of the solution (Delta H-sol(m)) at various molalities in water from (288.15 +/- 0.01) to (308.15 +/- 0.01) K in intervals of 5 K. Using Archer's method, we obtained the standard molar enthalpy of solution for [C(2)mim][Ala] (Delta H-sol(m)theta) and calculated its apparent relative molar enthalpy (L-Phi). Using Glasser's theory of lattice energy, we obtained the lattice energy, U-POT = 566 kJ . mol(-1), the hydration enthalpy of the cation and anion, (Delta H+ + Delta H-) = -620 kJ . mol(-1) , and the hydration enthalpy of an anion, Delta H-([Ala](-)) = 387 kJ . mol(-1) at 298.15 K. Finally, we obtained the heat capacity of aqueous [C(2)mim][Ala(C-p(sol))and its apparent molar heat capacity (C-Phi(p)) at various specific molalities.