Theoretical Studies of the Hydrolysis of the Methyl Phosphate Anion

Ching Han Hu, Tore Brinck

Research output: Contribution to journalArticle

88 Citations (Scopus)

Abstract

The mechanism for the hydrolysis of the methyl phosphate anion was studied using high-level ab itiitio and density functional theory methods. Starting from the molecular species CH3OPO3H-, CH3OP3H-·(H2O), and CH3OPO3H-(H2O)2, gas phase reaction coordinates of the proposed mechanisms were followed. Solvation free energies were evaluated using the polarizable continuum model (PCM) at the stationary point geometries. The dissociative mechanism, which involves the formation of a metaphosphate ion (PO3 -), is found to be more favorable than the associative mechanism, which involves a pentacoordinated intermediate, both in the gas phase and in aqueous solution. In the dissociative mechanism, the first step is rate determining. The computed free energy of activation in solution is within 1.7 kcal/mol of the experimentally determined activation free energy for hydrolysis. The first step and the second step in the dissociative mechanism are each shown to proceed via a six-centered water-assisted transition state.

Original languageEnglish
Pages (from-to)5379-5386
Number of pages8
JournalJournal of Physical Chemistry A
Volume103
Issue number27
DOIs
Publication statusPublished - 1999 Jul 8

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Free energy
Anions
hydrolysis
Hydrolysis
phosphates
Phosphates
anions
Gases
Chemical activation
free energy
Solvation
Density functional theory
activation
Ions
vapor phases
Geometry
Water
solvation
density functional theory
continuums

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

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abstract = "The mechanism for the hydrolysis of the methyl phosphate anion was studied using high-level ab itiitio and density functional theory methods. Starting from the molecular species CH3OPO3H-, CH3OP3H-·(H2O), and CH3OPO3H-(H2O)2, gas phase reaction coordinates of the proposed mechanisms were followed. Solvation free energies were evaluated using the polarizable continuum model (PCM) at the stationary point geometries. The dissociative mechanism, which involves the formation of a metaphosphate ion (PO3 -), is found to be more favorable than the associative mechanism, which involves a pentacoordinated intermediate, both in the gas phase and in aqueous solution. In the dissociative mechanism, the first step is rate determining. The computed free energy of activation in solution is within 1.7 kcal/mol of the experimentally determined activation free energy for hydrolysis. The first step and the second step in the dissociative mechanism are each shown to proceed via a six-centered water-assisted transition state.",
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Theoretical Studies of the Hydrolysis of the Methyl Phosphate Anion. / Hu, Ching Han; Brinck, Tore.

In: Journal of Physical Chemistry A, Vol. 103, No. 27, 08.07.1999, p. 5379-5386.

Research output: Contribution to journalArticle

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AU - Hu, Ching Han

AU - Brinck, Tore

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