Determination and Correlation of Pyridazin-3-amine Solubility in Eight Organic Solvents at Temperatures Ranging from (288.05 to 333.35) K

Using a synthetic method, the solubility data of pyridazin-3-amine were obtained in methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-propanone, ethyl acetate, and aniline at temperatures ranging from (288.05 to 333.35) K at atmospheric pressure. The fusion enthalpy and melting point were measured by differential scanning calorimetry. Modified Apelblat, λh, and Wilson models of nonideal solution were used to correlate the measured solubility data, respectively. Among them, Apelblat and λh equations have satisfying fitting effects for the experimental solubility values in all selected solvents with the root-mean-square deviation being less than 1.58 %. The activity coefficients of pyridazin-3-amine and molar dissolution enthalpy, entropy, and Gibbs free energy of the solute in methanol, 1-propanol, and 2-propanol were calculated in accordance with the parameters of the Wilson model at experimental solubility points.