Synthesis and thermodynamics studies of ionic liquid 1-methyl-3-pentylimidazolium bromide ([C5mim][Br]) with amino acids (l-cysteine and N-acetyl-l-cysteine) at different temperatures

Ionic liquid 1-methyl-3-pentylimidazolium bromide have been synthesised and confirmed by characterisation techniques H1 NMR, C13 NMR, MASS and IR spectroscopy. Density and speed of sound of aqueous amino acids (L-cysteine and N-acetyl-l-cysteine) in aqueous ionic liquid (0.005, 0.01, 0.03, 0.05) mol⋅kg−1 as solvent have been determined at four different temperatures T = (288.15, 298.15, 308.15, 318.15) K. Using these experimental data apparent molar volumes (Vϕ), limiting apparent molar volume (Vϕ°), experimental slope (Sv), standard partial molar volumes of transfer (ΔVϕ0), Limiting apparent molar expansibilities (Eϕ∘), apparent molar isentropic compression (Кϕ,s), limiting apparent molar isentropic compression (κϕ,s0) and standard partial molar isentropic compression of transfer (Δκϕ,s0) have been evaluated. The pair and triplet interaction coefficient have also been calculated. The values of these parameters are helpful for interpretation in terms of solute-solute and solute-solvent interactions, ion hydrophilic, hydrophilic-hydrophilic and hydrophilic-hydrophobic interactions in the amino acid and ionic liquid solutions. The structure making or structure-breaking tendency of amino acids has also been studied using these thermodynamic parameters.