Solubility data of zwitterions in water

In this work a series of ammonium- and phosphonium-based zwitterions (ZIs) namely: 3-(triethylammonio)propane-1-sulfonate, N222C3S, 4-(triethylammonio)butane-1-sulfonate, N222C4S, 3-(tributylammonio)propane-1-sulfonate, N444C3S, 4-(tributylammonio)butane-1-sulfonate, N444C4S, 3-(trihexylammonio)propane-1-sulfonate, N666C3S, 4-(trihexyl-ammonio)butane-1-sulfonate, N666C4S, 3-(tributylphosphonio)propane-1-sulfonate, P444C3S and 4-(tributyl-phosphonio)butane-1-sulfonate, P444C4S have been synthesized. The structure and purity of these compounds were confirmed by 1H NMR. The thermal properties such as temperature and enthalpy of (solid + solid) phase transition as well as the melting temperature of pure ZIs were evaluated by DSC technique. The (solid + liquid) and (liquid + liquid) phase equilibria measurements have been performed for eight binary systems of synthesized ZIs and one purchased 3-(1-pyridinio)-1-propanesulfonate [PyC3S] using the dynamic method and the experimental results were correlated using NRTL equation. Additionally, ternary system of {N666C3S (1) + N444C3S (2) + water (3)} with three different N666C3S to N444C3S initial molar fractions was determined.