L. Tan, M. Cocivera
Mar 15, 1982
Citations
0
Influential Citations
10
Citations
Journal
Canadian Journal of Chemistry
Abstract
Rapid addition of primary amino acids and imidazole to 4-formylpyridine to form carbinolamine intermediates in water has been studied by means of stopped-flow 1H nuclear magnetic resonance spectroscopy. The equilibrium constant Kn for this process was determined using stopped-flow uv spectroscopy. For the amino acid D,L-alanine and its derivatives, D,L-alanine methyl ester and D,L-alanylglycine, Kn does not appear to correlate with Ka, the acid dissociation constant. Values of kn, the addition rate constant, appear to be independent of pH and buffer concentration for these nucleophiles. The limited data indicate that the variation in rates of nucleophilic addition to 4-formylpyridine cannot be accounted for in terms of pKa, Kn or related to systematic changes in structure of the nucleophile. As a group, the primary amino acid D,L-alanine and its derivatives have comparable kn values within a factor of two in spite of their different pKa values. Imidazole, an aromatic secondary diamine, has a kn value that...