(Solid + liquid) phase equilibria of binary mixtures containing N-methyl-2-pyrrolidinone and ethers at atmospheric pressure

Solid–liquid equilibria (SLE), have been measured from 270 K to the boiling temperature of the solvent for 10 binary mixtures of N-methyl-2-pyrrolidinone, with ethers (dipropyl ether, dibutyl ether, dipentyl ether, methyl 1,1-dimethylethyl ether, methyl 1,1-dimethylpropyl ether, ethyl 1,1-dimethylpropyl ether, 1,4-dioxane, tetrahydrofuran, tetrahydropyran, 18-crown-6) using a dynamic method. The solubility of N-methyl-2-pyrrolidinone in ethers is lower than in alcohols and generally decreases with an increase of the number of carbon atoms of ether chain. The highest intermolecular solute–solvent interaction is observed for the cyclic ethers and for methyl 1,1-dimethylethyl ether. mental solubility results are compared with values calculated by means of the Wilson, UNIQUAC ASM and two NRTL equations utilizing parameters derived from SLE results. The existence of a solid–solid first-order phase transition in 18-crown-6 ether has been taken into consideration in the calculations. The correlation of the solubility data has been obtained with the average root-mean-square deviation of temperature σT = 0.9 K with UNIQUAC ASM and two NRTL equations and 0.6 K with the Wilson equation.