Equilibrium Solubilities of 2-Cyanoguanidine in Water + (Ethane-1,2-diol or N,N-Dimethylformamide) Mixtures at Different Temperatures: An Experimental and Correlational Study

The solid-liquid equilibrium of 2-cyanoguanidine in water + (ethane-1,2-diol, MEG, or N,N-dimethylformamide, DMF) mixtures within the temperature range from 278.15 K to 323.15 K at atmospheric pressure by using a static equilibrium method. Its corresponding (solid + liquid) equilibrium data will provide essential support for industrial design and further theoretical studies. The solubility of 2-cyanoguanidine in mixed solvents of (water + MEG) and (water + DMF) increased with increasing temperature, but the rate of solubility is different. The ideal solution, the modified Apelblat equation, and the semiempirical Buchowski-Ksiazczak lambda h equation were used to correlate with the solubility of 2-cyanoguanidine. The sum of the root-mean-square deviations was < 2.598.10(-3), the relative deviation < 4.844.10(-2) for phi(1) = 0.025 to 0.186 in (water + MEG) mixed solvents, and the root-mean-square deviations < 3.412.10(-3), the relative deviation < 4.941.10(-2) for phi(2) = 0.025 to 0.189 in (water + DMF). By comparing the models, the modified Apelblat equation provides a more accurate mathematical representation of the experimental data.