Base, definition hydrolysis, catalysis

A second form of acid—base catalysis reflects another, more general definition of acids and bases. In the Lewis formulation, an acid is an electron-pair acceptor, and a base is an electron-pair donor. Metal ions, including such biologically important ones as Mn +, Mg +, and Zn, are Lewis acids. Thus, they can play a role in metal-ion catalysis (also called Lewis acid-base catalysis). The involvement of Zn + in the enzymatic activity of carboxypeptidase A is an example of this type of behavior. This enzyme catalyzes the hydrolysis of... 

Small hydrogen isotope effects have been found in a nucleophilic substitution of an aromatic heterocycle, the reaction of cyanuric chloride with aniline-N,N-d2 in benzene solution (Zollinger, 1961a). As the effects are small (5%), it is difficult to draw definite mechanistic conclusions. The reactions of cyanuric chloride and other halogenated triazine derivatives are subject to bifunctional catalysis (e.g. by carboxylic acids and by a -pyridone) and to catalysis by monofunctional bases like pyridine (Bitter and Zollinger, 1961). Reinheimer et al. (1962) measured the solvent isotope effect in the hydrolysis of 2-chloro-5-nitro-pyridine (A h,o/ d.o = 2 36). The result makes it probable, but... 

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