Effect of solvent composition on the acidity of phenols in dimethyl sulfoxide–water mixtures

✍ Scribed by Richard M. Tarkka; Ik-Hwan Um; Hai-Qi Xie; Alan-Pierre Chatrouse; Francois Terrier; Shmaryahu Hoz; Erwin Buncel

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 83 KB
• Volume: 11
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199812)11:12<847::aid-poc42>3.0.co;2-5

✦ Synopsis

The effect of solvent composition on the acidity of substituted phenols in DMSO-H 2 O systems was examined. It is shown that in DMSO-H 2 O mixtures with up to 35 mol% DMSO there is a linear relationship between the pK a values of monosubstituted phenols in the binary solvent mixtures of different compositions and the corresponding pK a values in water. This leads to an equation relating the slope and intercept terms, pK a (DMSO-H 2 O) = slope[pK a (H 2 O)] intercept. The basis of this relationship in the Kirkwood-Westheimer equation is examined. The significance of a possible 'supersolvent' is discussed. The applicability of the relationships derived herein to other rate-equilibria relationships and solvent mixtures is considered.