Studies on Models for Tetrahydrofolic Acid. V.A Kinetically Significant Transport Process in General Base Catalyzed Aminolysis of a Formamidine

W. P. Bullard, L. J. Farina, P. R. Farina, S. J. Benkovic

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The methoxyaminolysis of the unsymmetrically substituted formamidine I exhibits general base catalysis by amines, phosphate, and carboxylates. The catalytic constants are best correlated in the Bronsted relationship by two straight lines of d β ≃ 1 and β ≃ 0 for pKBH+ < 1.5 and pKBH+ > 1.5, respectively, suggesting the existence of a short-lived covalent intermediate and kinetically significant transport processes. The data support a mechanism in which two sequential proton transfers occur, perhaps within a single encounter complex, the rate-limiting steps being (1) diffusion-controlled encounter of the intermediate and general base species for strong bases, and (2) either diffusion separation of or a “reorganization” within the encounter complex for weaker bases. General considerations for the aminolysis of amidines and certain enzymic reactions.

Original languageEnglish (US)
Pages (from-to)7295-7302
Number of pages8
JournalJournal of the American Chemical Society
Volume96
Issue number23
DOIs
StatePublished - Nov 1 1974

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Amidines
Proton transfer
Acids
Catalysis
Amines
Protons
Phosphates
formamidine
5,6,7,8-tetrahydrofolic acid

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

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title = "Studies on Models for Tetrahydrofolic Acid. V.A Kinetically Significant Transport Process in General Base Catalyzed Aminolysis of a Formamidine",
abstract = "The methoxyaminolysis of the unsymmetrically substituted formamidine I exhibits general base catalysis by amines, phosphate, and carboxylates. The catalytic constants are best correlated in the Bronsted relationship by two straight lines of d β ≃ 1 and β ≃ 0 for pKBH+ < 1.5 and pKBH+ > 1.5, respectively, suggesting the existence of a short-lived covalent intermediate and kinetically significant transport processes. The data support a mechanism in which two sequential proton transfers occur, perhaps within a single encounter complex, the rate-limiting steps being (1) diffusion-controlled encounter of the intermediate and general base species for strong bases, and (2) either diffusion separation of or a “reorganization” within the encounter complex for weaker bases. General considerations for the aminolysis of amidines and certain enzymic reactions.",
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Studies on Models for Tetrahydrofolic Acid. V.A Kinetically Significant Transport Process in General Base Catalyzed Aminolysis of a Formamidine. / Bullard, W. P.; Farina, L. J.; Farina, P. R.; Benkovic, S. J.

In: Journal of the American Chemical Society, Vol. 96, No. 23, 01.11.1974, p. 7295-7302.

Research output: Contribution to journalArticle

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T1 - Studies on Models for Tetrahydrofolic Acid. V.A Kinetically Significant Transport Process in General Base Catalyzed Aminolysis of a Formamidine

AU - Bullard, W. P.

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AB - The methoxyaminolysis of the unsymmetrically substituted formamidine I exhibits general base catalysis by amines, phosphate, and carboxylates. The catalytic constants are best correlated in the Bronsted relationship by two straight lines of d β ≃ 1 and β ≃ 0 for pKBH+ < 1.5 and pKBH+ > 1.5, respectively, suggesting the existence of a short-lived covalent intermediate and kinetically significant transport processes. The data support a mechanism in which two sequential proton transfers occur, perhaps within a single encounter complex, the rate-limiting steps being (1) diffusion-controlled encounter of the intermediate and general base species for strong bases, and (2) either diffusion separation of or a “reorganization” within the encounter complex for weaker bases. General considerations for the aminolysis of amidines and certain enzymic reactions.

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