Volumetric properties, viscosity and taste behavior of MDMA-HCl in aqueous binary and (water plus D-lactose) ternary mixtures at different temperatures

Experimental measurements of density and viscosity of 3,4-methylenedioxymethamphetamine hydrochloride (MDMA-HCl) in aqueous binary and in (water + D-lactose) ternary mixtures have been investigated in different temperature and molality ranges: from (293.15 to 313.15) K and from (0.05 to 0.5) mol.kg(-1). In order to study interactions between solute and solvent, besides obtained experimental results for density and viscosity, computational analysis was conducted. From calculated apparent molar volumes, apparent molar volume at infinite dilution, Hepler's coefficient and viscosity B-coefficients, and hydration number of MDMA-HCl, it was found that in binary aqueous mixture and in (water + D-lactose) ternary mixture MDMA-HCl acting as cosmotropic substance. The taste of MDMA-HCl in these two systems was evaluated through calculated values of apparent specific molar volumes at infinite dilution. The structural entropy and entropy of solvation for MDMA-H+ ion was calculated. It was concluded that the taste of MDMA-HCl is basically bitter and becomes more bitter in the presence of lactose, which is explained by desolvation properties of the D-lactose and by strong interactions between MDMA-HCl and D-lactose. (C) 2019 Elsevier Ltd.