HYDROGEN-BONDING .25. THE SOLVATION PROPERTIES OF METHYLENE IODIDE

Ostwald solubility coefficients, L, have been determined for 37 gases and vapours in methylene iodide at 298 K, and have been correlated through equation (i), where the solute explanatory log L = -0.74 + 0.32R2 + 1.347pi2H + 0.83alpha2H + 1.19beta2H + 0.87 log L16 (i) variables are R2 an excess molar refraction, pi2H the solute dipolarity/polarisability, alpha2H and beta2H the solute hydrogen-bond acidity and basicity, and log L16 where L16 is the solute Ostwald solubility coefficient on hexadecane at 298 K. Similar equations have been constructed for solvation of solutes in tetrachloromethane, trichloromethane and 1,2-dichloroethane using literature data. It is shown that polarisability effects favour solvation in methylene iodide, through the R2 term, but that such effects enhance the solubility of polarisable solutes only moderately: thus the R2 term contributes 0.4 log units more in methylene iodide than in trichloromethane for the solute benzene. Examination of DELTAG-degrees, DELTAH-degrees and DELTAS-degrees for solvation of gaseous solutes suggests also that polarisability effects in methylene iodide are not very much larger than in the other halogenated solvents.