A scale of solute hydrogen-bond basicity has been set up using log K values for the complexation of a series of bases ( i ) against a number of reference acids in dilute solution in tetrachloromethane, equation (i).Thirty-four such linear equations have been solved t o yield 1, and 0, values that characterise the acids, and log K$ values that characterise the base; all the thirty-four equations intersect at a point where log K = -1.1 with K on the molar scale. This primary set of log K z values involved 215 bases, and through a large number of secondary values we have been able to determine log K! for some 500 bases, that include nearly all the functional groups encountered in organic chemistry. By making use of the 'magic point,' we have transformed log K t into an entirely equivalent, but more convenient, scale through equation (ii). p ; = (log K,H + 1.1)/4.636 (ii) Since w e can take p? = 0 for all non-basic compounds such as alkanes and cycloalkanes, the new p ; hydrogen-bond solute basicity scale covers virtually all classes of base.We show that p$ is not generally related to measures of full proton-transfer basicity such as aqueous pK or gaseous proton affinity (€pa) values, although family dependence is observed, and w e stress that solute hydrogen-bond basicity must not be equated with full proton-transfer basicity. We also briefly investigate the solvent dependence of the pc values in terms of the Maria-Gal &value, and w e point out a number of exclusions t o the 'reasonably general' p ; scale.

SK 70 4TG * These K z values are formally equivalent to equilibrium constants for the series of acids against a particular base with L, = 1 and D, = 0.

Olive oil-gas partition coefficients, Lo,,, have been determined for 80 solutes at 310 K using a gas chromatographic method in which olive oil is used as the stationary phase. Combination with other literature values has enabled a list of 140 log L o i , values at 31 0 K to be constructed. Hexadecane-gas partition coefficients, Lhex, have similarly been determined for 140 solutes at 298 K, and used to obtain a reasonably comprehensive list of log Lhex values for ca. 240 solutes at 298 K. It is shown that olive oilwater partition coefficients, Poi,, calculated indirectly from Loir and Cwater partition coefficients agree quite well with directly determined Poi,. values. Similarly, hexadecane-water partition coefficients, Phex, obtained from Lhex and Lwater agree with directly determined values. It is suggested that in the case of the t w o particular solvents, olive oil and hexadecane, mutual miscibility of the two phases is of little consequence, and that Po,, and Phex values can conveniently be obtained by combining the respective solventgas and water-gas partition coefficients.

Solvent effects on a number of different processes have been surveyed, and results of the application of multiple linear regression analysis are discussed. The processes examined include examples of solubility of gases or vapours, distribution coefficients of solutes between water and a series of solvents, and solvent effects on conformational equilibria, on keto-en01 tautornerism, and on reaction rates. It is shown that two particular equations, that due to Koppel and palm and extended by Makitra and Pirig, and that due to Abraham, Kamlet, and Taft, can cope quite satisfactorily with solvent effects on these various processes. It is pointed out that interpretation of parameters obtained from equations that involve macroscopic quantities such as AG* or AGO is not necessarily straightforward, and that some model is needed in order to interpret these macroscopic quantities in terms of qicroscopic quantities that can characterise, for example, solute-solvent interactions.

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