Quantitative Macroscopic Analysis of Solvent Effects with Emphasis on
Pericyclic and Solvolysis Reactions
Joseph J. Gajewski
Department of Chemistry
Indiana University
The response of the Claisen Rearrangement to solvents in a manner not
unlike the solvolysis of tert-butyl chloride solvolysis required
understanding of both reactions. A multiparameter equation utilizing the
Kirkwood-Onsager function of dielectric constant, the Hildebrand cohesive
energy density, and the free energies of transfer of chloride ion and
potassium ion between bulk solvents to address specific hydrogen bond
donation and basicity, respectively, has been applied to these and related
reactions to assess changes in dipole moment, solvophobicity, and specific
acidity and basicity requirements of ground and transition states. The
bottom line is that the hydrophobic effect is an important contributor in
both reactions, and in solvolysis reactions, solvent basicity or
nucleophilicity appears to play no role.