Studies on the Decarboxylation of Amino Acids with Glyoxal

Decarboxylation of about twenty kinds of α, β and γ-amino acids in the reaction with glyoxal or ninhydrin was investigated. The decarboxylation rate of amino acids proved that steric and polar effects had important roles in the reaction.

From the data of pK₂ values and decarboxylation rates of amino acids, it can be concluded that under a similar steric environment, the decarboxylation rate depends on the anion concentration of amino acids.

Besides carbon dioxide, acetaldehyde, 2-propanone and propionaldehyde were respectively detected from the reaction of β-alanine, β and γ-amino-n-butyric acids with glyoxal or ninhydrin. The decarboxylation mechanism of these amino acids seemed to take place through the corresponding β- or γ-keto acid.

Oxygen absorption was also observed from the reaction of amino acids with dicarbonyl compounds.