The gas phase aldose-ketone isomerization mechanism: Direct interconversion of the model hydroxycarbonyls 2-hydroxypropanal and hydroxyacetone.

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Bibliographic Details
Title:	The gas phase aldose-ketone isomerization mechanism: Direct interconversion of the model hydroxycarbonyls 2-hydroxypropanal and hydroxyacetone.
Authors:	Sun, Jing¹, So, Sui¹, da Silva, Gabriel¹ gdasilva@unimelb.edu.au
Source:	International Journal of Quantum Chemistry. 10/15/2017, Vol. 117 Issue 20, pn/a-N.PAG. 5p.
Subjects:	Hydroxypropanone, Hydroxycarbonyls, Gas phase reactions, Isomerization, Aldoses, Ketones
Abstract:	We report a novel mechanism for the interconversion of 2-hydroxypropanal with its more-stable ketone isomer hydroxyacetone. Reaction proceeds via concerted transfer of two H atoms, requires a barrier of only ∼40 kcal mol−1, bypasses the enediol intermediate, and is general for α-hydroxy carbonyls. A similar isomerization mechanism is shown to persist for β, γ, and δ-hydroxy carbonyls; these compounds are skeletal forms of the monosaccharides and this work, therefore, discloses the gas-phase mechanism for aldose-ketose isomerization. As an example, the isomerization of glyceraldehyde to dihydroxyacetone is shown to proceed via this mechanism with a barrier of 31 kcal mol−1. Rate coefficients and thermochemical properties are reported for the isomerization of 2-hydroxypropanal and hydroxyacetone for use in detailed kinetic models. Additionally, RRKM theory k( E) values for this reaction suggest that it may transpire in the troposphere following solar excitation. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	We report a novel mechanism for the interconversion of 2-hydroxypropanal with its more-stable ketone isomer hydroxyacetone. Reaction proceeds via concerted transfer of two H atoms, requires a barrier of only ∼40 kcal mol−1, bypasses the enediol intermediate, and is general for α-hydroxy carbonyls. A similar isomerization mechanism is shown to persist for β, γ, and δ-hydroxy carbonyls; these compounds are skeletal forms of the monosaccharides and this work, therefore, discloses the gas-phase mechanism for aldose-ketose isomerization. As an example, the isomerization of glyceraldehyde to dihydroxyacetone is shown to proceed via this mechanism with a barrier of 31 kcal mol−1. Rate coefficients and thermochemical properties are reported for the isomerization of 2-hydroxypropanal and hydroxyacetone for use in detailed kinetic models. Additionally, RRKM theory k( E) values for this reaction suggest that it may transpire in the troposphere following solar excitation. [ABSTRACT FROM AUTHOR]
ISSN:	00207608
DOI:	10.1002/qua.25434