Solubility of Imidazoles in Ethers

Journal of Chemical & Engineering Data (Impact Factor: 2.05). 02/2003; 48(3). DOI: 10.1021/je020113t

ABSTRACT Solid−liquid equilibrium (SLE) has been measured from 270 K to the melting temperature of the solid for 15 binary mixtures of an imidazole (1H-imidazole, 2-methyl-1H-imidazole, and 1,2-dimethylimidazole) with ethers [dipropyl ether, dibutyl ether, dipentyl ether, methyl 1,1-dimethylethyl ether (tert-butyl methyl ether), and methyl 1,1-dimethylpropyl ether (tert-amyl methyl ether)] using a dynamic method. The solubility of imidazoles in ethers is lower than that in alcohols and in water and generally decreases with increasing of the ether chain length. Additionally, two liquid phases were observed for mixtures of 1H-imidazole and 1,2-dimethylimidazole in dibutyl ether and dipentyl ether. The intermolecular solute−solvent interaction is higher for branch chain ethers, and the mutual solubility is much higher, which results in one liquid phase being observed. Experimental results of solubility are compared with values calculated by means of the Wilson, UNIQUAC, and NRTL equations utilizing parameters derived from SLE results. The existence of a solid−solid first-order phase transition in 2-methyl-1H-imidazole has been observed and has been taken into consideration in the solubility calculation. The best correlation of the solubility data was obtained with the Wilson equation.