Push-pull and bifunctional acid-base catalysis

5 Push-pull and bifunctional acid-base catalysis 

In the 1950s, the push-pull mechanism whereby a proton is donated by one centre and received at another was considered as a major contributor to enzyme catalysis and to give rise to third-order terms in non-enzymic reactions. Third-order terms were observed in organic solvents but in water they are of minor importance because of the solvating power of this solvent for ions and polar centres. 

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