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Correlation and estimation of gas-chloroform and water-chloroform partition coefficients by a linear free energy
M H Abraham1, J A Platts, A Hersey
1Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, U.K.; Science Development Group, GlaxoWellcome Research and Development, Park Road, Ware SG12 0DP, U.K.; Seaver Chemistry Laboratory, Pomona College, Claremon.
Abstract:
A linear free energy relationship, LFER, has been used to correlate 150 values of gas-chloroform partition coefficients, as log Lchl with a standard deviation, sd, of 0.23 log units, a correlation coefficient r2 of 0.985, and an F-statistic of 1919. The equation reveals that bulk chloroform is dipolar/polarizable, of little hydrogen-bond basicity, but as strong a hydrogen-bond acid as bulk methanol or bulk ethanol. However, the main influence on gaseous solubility in chloroform is due to solute-solvent London dispersion interactions. A slightly modified LFER has been used to correlate 302 values of water-chloroform partition coefficients, as log Pchl. The correlation equation predicts log Pchl for a further 34 compounds not used in the equation with sd = 0.17 log units. When the LFER is applied to all 335 log Pchl values, the resulting equation has sd = 0.25, r2 = 0.971, and F = 2218.