Contents 1 Introduction......................................................... 1 2 Solute-Solvent Interactions.. Solutions 2.4 ntermolecular Forces.,..,..,,..,,,.,.,.,.,...,,...,.,...,,.,.,... 510 2.2.1 Ion-Dipole Forces....................................... 10 2.2. Dipole-Dipole Forces.. 2.3 Dipole-Induced Dipole Forces 2.2.4 Instantaneous Dipole-Induced Dipole Forces......................... 13 2.2.5 Hydrogen Bonding... 2.2.6 Electron-Pair Donor/Electron-Pair Acceptor Interactions(EPD/EPA nteractions)............................................... 。。。。。。 19 2.2.7 Solvophobic Interactions............................................ 7 2.3 Solvation 30 2.4 Selective Solvation. 38 2.5 Micellar Solvation(Solubilization)........ 42 2.6 Ionization and Dissociation..... 46 3 Classification of Solvents. 57 3.1 Classification of Solvents according to Chemical Constitution......... 3.2 Classification of Solvents using Physical Constants. 62 3.3 Classification of Solvents in Terms of Acid-Base Behaviour.... 3.3.1 Bronsted-Lowry Theory of Acids and Bases.......................... 13 3.3.2 Lewis Theory of Acids and Bases.. 9 3.4 Classification of Solvents in Terms of Specific Solute/Solvent Interactions.. 82 3.5 Classification of Solvents using Multivariate Statistical Methods....... 4 Solvent Effects on the Position of Homogeneous Chemical Equilibria.... 93 4.1 General Remarks. 93 4.2 Solvent Effects on Acid/Base Equilibria... 95 4.2.1 Bronsted Acids and Bases in Solution...... 95 42.2 Gas-Phase Acidities and Basicities. 99 4.3 Solvent Effects on Tautomeric Equilibria 106 43.1 Solvent Effects on Keto/Enol Equilibria. 106 432 Solvent Effects on other Tautomeric Equilibria 113 44 Solvent Effects on other Equilibria. 121 441 Solvent effects on Bronsted acid/Base equilibria 121 4.4.2 Solvent effects on lewis acid/Base equilibria 123 443 Solvent Effects on Conformational Equilibria 126 4.4.4 Solvent effects on cis/trans or e/z Isomerization eauilibria 132 A45 Solvent Effects on Valence Iso erization Equilibria 135 446 ent Effects on Electron-Transfer Equilibria 137 44.7 ent Effects on Host/Guest Complexation Equilibria. 139Contents 1 Introduction ......................................................... 1 2 Solute-Solvent Interactions ........................................... 5 2.1 Solutions . .......................................................... 5 2.2 Intermolecular Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.1 Ion-Dipole Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.2 Dipole-Dipole Forces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2.3 Dipole-Induced Dipole Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.4 Instantaneous Dipole-Induced Dipole Forces . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.5 Hydrogen Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.2.6 Electron-Pair Donor/Electron-Pair Acceptor Interactions (EPD/EPA Interactions) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.2.7 Solvophobic Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.3 Solvation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2.4 Selective Solvation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.5 Micellar Solvation (Solubilization) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.6 Ionization and Dissociation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 3 Classification of Solvents............................................. 57 3.1 Classification of Solvents according to Chemical Constitution . . . . . . . . . 57 3.2 Classification of Solvents using Physical Constants . . . . . . . . . . . . . . . . . . . . 62 3.3 Classification of Solvents in Terms of Acid-Base Behaviour. . . . . . . . . . . . 73 3.3.1 Brønsted-Lowry Theory of Acids and Bases . . . . . . . . . . . . . . . . . . . . . . . . . . 73 3.3.2 Lewis Theory of Acids and Bases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 3.4 Classification of Solvents in Terms of Specific Solute/Solvent Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 3.5 Classification of Solvents using Multivariate Statistical Methods . . . . . . . 84 4 Solvent E¤ects on the Position of Homogeneous Chemical Equilibria .... 93 4.1 General Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 4.2 Solvent E¤ects on Acid/Base Equilibria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.2.1 Brønsted Acids and Bases in Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.2.2 Gas-Phase Acidities and Basicities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 4.3 Solvent E¤ects on Tautomeric Equilibria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 4.3.1 Solvent E¤ects on Keto/Enol Equilibria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 4.3.2 Solvent E¤ects on other Tautomeric Equilibria . . . . . . . . . . . . . . . . . . . . . . . 113 4.4 Solvent E¤ects on other Equilibria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.4.1 Solvent E¤ects on Brønsted Acid/Base Equilibria . . . . . . . . . . . . . . . . . . . . . 121 4.4.2 Solvent E¤ects on Lewis Acid/Base Equilibria . . . . . . . . . . . . . . . . . . . . . . . . 123 4.4.3 Solvent E¤ects on Conformational Equilibria . . . . . . . . . . . . . . . . . . . . . . . . . 126 4.4.4 Solvent E¤ects on cis/trans or E/Z Isomerization Equilibria . . . . . . . . . . . 132 4.4.5 Solvent E¤ects on Valence Isomerization Equilibria . . . . . . . . . . . . . . . . . . . 135 4.4.6 Solvent E¤ects on Electron-Transfer Equilibria . . . . . . . . . . . . . . . . . . . . . . . 137 4.4.7 Solvent E¤ects on Host/Guest Complexation Equilibria . . . . . . . . . . . . . . . 139