Enolisation, the first stage of carbonyl reactions

In contrast to the keto tautomer which can react with nucleophilic reagents, enol and enolate are the reactive forms on which electrophilic additions (2) can occur. 

A similar conclusion has been reached for many oxidation reactions, usually in acidic conditions rates are often zero-order with respect to the oxidising agent and equal to the rates of halogenation (for a review see Verter, 1970 for a recent report see, Audsley et al., 1980). 

Enolisation and ionisation are also the first stages of some elimination reactions, aldolisation, alkylation, etc., but in most cases the enolisation (or ionisation) process is not rate-limiting. Thermodynamic data on enol and enolate formation are needed to understand the kinetic behaviour of these reactions, but a complete picture must include data on the subsequent steps. 

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