Structure Breaking/Making Property of Acefylline Piperazine in Aqueous, Aqueous Methanol, and Aqueous Ethylene Glycol Systems

Abstract

Densities of acefylline piperazine (AP) in aqueous, aqueous methanol, and aqueous ethylene glycol (10% v/v) systems are determined in the concentration range 0.04-0.14±0.001 mol/dm3 at different temperatures (298.15-318.15 K) with the interval of 5 K. The apparent molar volume (φv), the partial molar volume $$(\phi_v^0)$$ , and the ion-ion interaction parameter (Sv) are calculated using the Masson equation. Partial molar expansibilities $$(\phi_E^0)$$ , which indicate the presence or absence of the caging or packing effect, are also evaluated and discussed. The results are interpreted in terms of solute-solvent and solute-solute interactions of AP in aqueous, aqueous methanol, and aqueous ethylene glycol systems. The structure-breaking and structure-making properties of AP are inferred by the sign of Hepler′s criterion $$(\partial^2\phi_v^0/\partial{T}^2)_p$$ , i.e. the second derivative of the partial molar volume with respect to the temperature at the constant pressure.