Effect of substituents on acidity

This would have both a solvent effect and a mass law effect on the rate of ester formation. The error is systematic, since it is most serious for the slower ester formation reactions, and consequently the p value calculated by Jaffe144 from the data of Hartman and Borders142 is not accurate. Later workers allowed for this side-reaction 46 or used aromatic sulphonic acids rather than HC1 as the catalyst145147. However, whatever the exact p values, it is quite clear that the polar effects of substituents on acid-catalyzed ester hydrolysis and formation are small. 

It is possible to break down the effect of substituents on acidity or basicity into the effect on the charged species on the one hand and on the corresponding neutral species on the other. For example, the effect of substituents on the acidity of aniline (reaction 4) is given by the difference between the interaction energies for the appropriate substituted anilide ion (reaction 7) ... 

Effect of Substituents on Acidities of Phenols (kcal mole )... 

TABLE 18.2 Effect of Substituents on Acidity of Carboxylic Acids ... 

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