Physicochemical and thermodynamic properties of the {1-alkyl-1-methylmorpholinium bromide, [C1Cn=3,4,5MOR]Br, or 1-methyl-1-pentylpiperidinium bromide, [C1C5PIP]Br + water} binary systems

• The aqueous solutions of the [C1C3MOR]Br, [C1C4MOR]Br, [C1C5MOR]Br, [C1C5PIP]Br have been studied.
• The density, dynamic viscosity, heat capacity and phase equilibria have been determined.
• The experimental data have been correlated using relevant equations.

In this study, the density, ρ, dynamic viscosity, η, (solid + liquid), SLE and (vapor + liquid), VLE phase equilibria of four binary systems (ionic liquid, IL + water) are determined. Heat capacities, Cp of (organic salt + water) mixtures were studied as well. In this work, a series of organic salts namely: 1-mehyl-1-propylmorpholinium bromide, [C1C3MOR]Br, 1-mehyl-1-butylmorpholinium bromide, [C1C4MOR]Br, 1-mehyl-1-pentylmorpholinium bromide, [C1C5MOR]Br and 1-methyl-1-pentylpiperidinium bromide, [C1C5PIP]Br have been synthesized. The structure of the synthesized compounds were confirmed by 1H NMR, 13C NMR and elemental analysis. The thermophysical characterization of pure organic salts, including: temperature of phase transition (Ttr), enthalpy of phase transition (ΔtrH), melting temperature (Tm) and enthalpy of melting (ΔmH) have been determined using differential scanning microcalorimetry technique (DSC) at atmospheric pressure. Additionally, the thermogravimetry technique (TG/DTA) was used to determine the decomposition temperature. The influence of the alkyl chain length in the morpholinium cation as well as the cation structure on the physicochemical and thermodynamic properties presented in this work are discussed.