Brpnsted catalysis law

The relative rate constants (k /ki) reflect the relative rates for intra- and intermolecular proton transfer, respectively. As discussed for disilene, the Brpnsted catalysis law must be applied to determine the relative rates, where ki and k are expected to increase with the... 

A number of studies of fhe acid-cafalyzed mechanism of enolizafion have been done, and the case of cyclohexanone is illustrative. The reaction is catalyzed by various carboxylic acids and substituted ammonium ions. The effectiveness of these proton donors as catalysts correlates with their values. When plotted according to the Brpnsted catalysis law (Section 3.6.1) the value of fhe slope a is 0.74. When deuterium or tritium is introduced in the a-position, there is a marked decrease in the rate of acid-catalyzed enolization h/ d 5. This kinetic isotope effect indicates that the C-H bond cleavage is part of the rate-determining step. The generally accepted mechanism for acid-catalyzed enolization pictures the rate-determining step as deprotonation of the protonated ketone. 

The Brpnsted relationship (see Section 3.7.1.2 to review the Brpnsted catalysis law) shows a correlation with the identity of the alkoxy group. The alkoxy groups derived from more acidic alcohols have lower Brpnsted coefficients a. 

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