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Curley K, Pratt RF. Structure of an alpha-Keto beta-Amido Acid, 3-(Phenylacetamido)pyruvic Acid, and Its Methyl Ester in the Solid State and in Organic and Aqueous Solvents. J Org Chem. 1997;62(13):4479-4483doi: 10.1021/jo970223g.
Curley, K., & Pratt, R. F. (1997). Structure of an alpha-Keto beta-Amido Acid, 3-(Phenylacetamido)pyruvic Acid, and Its Methyl Ester in the Solid State and in Organic and Aqueous Solvents. The Journal of organic chemistry, 62(13), 4479-4483. https://doi.org/10.1021/jo970223g
Curley, Kieran, and Pratt, R. F.. "Structure of an alpha-Keto beta-Amido Acid, 3-(Phenylacetamido)pyruvic Acid, and Its Methyl Ester in the Solid State and in Organic and Aqueous Solvents." The Journal of organic chemistry vol. 62,13 (1997): 4479-4483. doi: https://doi.org/10.1021/jo970223g
Curley K, Pratt RF. Structure of an alpha-Keto beta-Amido Acid, 3-(Phenylacetamido)pyruvic Acid, and Its Methyl Ester in the Solid State and in Organic and Aqueous Solvents. J Org Chem. 1997 Jun 27;62(13):4479-4483. doi: 10.1021/jo970223g. PMID: 11671778.
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J Org Chem. 1997 Jun 27;62(13):4479-4483. doi: 10.1021/jo970223g.

Structure of an alpha-Keto beta-Amido Acid, 3-(Phenylacetamido)pyruvic Acid, and Its Methyl Ester in the Solid State and in Organic and Aqueous Solvents.

The Journal of organic chemistry

Kieran Curley, R. F. Pratt

Affiliations

  1. Department of Chemistry, Wesleyan University, Middletown, Connecticut 06459.

PMID: 11671778 DOI: 10.1021/jo970223g

Abstract

3-(Phenylacetamido)pyruvic acid and its methyl ester both exist in the enol form in the solid state and when dissolved in organic solvents. In aqueous solution, the pK(a)'s of the enol acid are 3.28 (CO(2)H) and 10.14 (enolic OH) and that of the ester is 8.14 (enolic OH). The thermodynamically stable form of both acid and ester in aqueous solution, however, is the keto species. Ketonization rates of 3-(phenylacetamido)pyruvic acid were determined spectrophotometrically in acid and in buffered solution at neutral pH. The dominant reaction at low pH is the pH-independent protonation of the enol carboxylate monoanion with a rate constant of 0.062 s(-)(1) M(-)(1). At neutral pH, the ketonization in water alone is very slow but is strongly catalyzed by buffer acids. Rapid, partial (ca. 30%) hydration of the keto form also occurs in aqueous solution. The pK(a) of the pyruvate as a carbon acid is around 12.5. These results are compared with literature data for pyruvic acid itself. Application of peptidyl pyruvates and their derivatives as protease inhibitors requires careful assessment of the complications illustrated by the behavior of 3-(phenylacetamido)pyruvic acid and its methyl ester in aqueous solution.

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