Catalysis, general acid dioxide

Carbon atom, 4. See also Atomic orbitals Carbon dioxide hydration, 197-199. See also Carbonic anhydrase Carbonic anhydrase, 197-199,200 Carbonium ion transition state, 154, 159 Carboxypeptidase A, 204-205 Catalysis, general acid, 153,164,169 in carboxypeptidase A, 204-205 free energy surfaces for, 160, 161 in lysozyme, 154... 

It should also be noted that decarboxylation of / -oxo acids is subject to specific catalysis by primary amines as well as to general catalysis. For example, the very smooth decarboxylation of 2,2-dimethylacetoacetic acid in water is uninfluenced by addition of a secondary or tertiary amine but its rate is increased by a factor of 10 on addition of aniline. The explanation lies in the fact that primary amines can react to form / -imino acids, whose imino-nitro-gen atom, being considerably more strongly basic than the ketonic oxygen atom, causes almost complete transfer of the proton from the carboxyl group, and it is this transfer that initiates the decomposition. A further example is the violent decomposition to acetone and carbon dioxide that occurs when a small amount of aniline is added to acetonedicarboxylic acid. 

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