By G. Charlot
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2. STANFORD, / . Chem. Phys. 9, 204 (1941). 3. GORDY, / . Chem. Phys. 9, 215 (1941). 4. LATIMER, Chem. Revs. 44, 59 (1949). 5. GOULDEN, Spectrochim. Ada 6, 129 (1954). 6. ANDREWS, Chem. Revs. 54, 713 (1954). 7. SMYTH, Dielectric Behaviour and Structure, McGraw-Hill, 1955. 8. , Pergamon, 1957, p. 163. 9. R . E . , p. 177. 44 CHEMICAL REACTIONS IN SOLVENTS A N D MELTS 10. PINEAU, N . L. JOSIEN, / . Chim. Phys. 55, 464 (1958). 11. S . P . M C G L Y N N , Chem. Revs. 58, 1113 (1958). 12. MACKLEN, Chem.
P. 59. shows the predicted differences between pKA in water and in various solvents S for various types of acid-base couples. The influence of the dielectric constant is the same for acids of the same form with the exceptions of phenols and picric acid which behave differently from other acids of type HA. Notes. 1. Analogous rules apply to the basicity constants: *B = [HB] [S] [B] Couples HB+/B: pKB increases as the dielectric constant decreases. Couples HB2+/B+: even stronger effect. Couples HA/A~: No effect.
Allen and Caldin2 have shown that the constants of the dimerization of benzoic and alkylcarboxylic acids often vary in the same sense as the pKA values in water, but they were not able to establish a quantitative relationship. It is the same for aliphatic amines and substituted pyridines. It is impossible at present to relate the two phenomena. Effect of Association due to Hydrogen Bonding on Acid-Base Reactions We are, most of all, interested to know how hydrogen bonds can affect acid-base reactions and how to take them into account.