Equilibrium Acidities of 2-Alkylthiazolium Cations at the C-2α Position

F. G. Bordwell; A. V. Satish; Frank Jordan; Carlos B. Rios; A. Chitong Chung

doi:10.1021/ja00158a045

Equilibrium Acidities of 2-Alkylthiazolium Cations at the C-2α Position

F. G. Bordwell, A. V. Satish, Frank Jordan, Carlos B. Rios, A. Chitong Chung

SASN Chemistry

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Abstract

The properties of the 2-(1-methoxyethyl)-3,4-dimethylthiazolium cation (3) and seven related thiazolium cations have been investigated as models for the behavior of 2-(1-hydroxyethyl)thiamin (1). The equilibrium acidity (pK^HA+) of 3 in Me₂SO solution was found to be 14.1 ± 0.05, and evidence is presented to indicate that the value in aqueous solution is within ±1 unit of this value. These values are 3 units, or more, lower than previous estimates for the pK^HA+ at C-2α of the thiazolium moiety in 1, which were based on kinetic measurements. Related thiazolium cations, where Me, RO, or Ph groups were introduced into the C-2 side chain, were found to have acidities in the 9-15 pK^HA+ range.

Original language	English (US)
Pages (from-to)	792-797
Number of pages	6
Journal	Journal of the American Chemical Society
Volume	112
Issue number	2
DOIs	https://doi.org/10.1021/ja00158a045
State	Published - Jan 1 1990

All Science Journal Classification (ASJC) codes

Catalysis
Chemistry(all)
Biochemistry
Colloid and Surface Chemistry

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title = "Equilibrium Acidities of 2-Alkylthiazolium Cations at the C-2α Position",

abstract = "The properties of the 2-(1-methoxyethyl)-3,4-dimethylthiazolium cation (3) and seven related thiazolium cations have been investigated as models for the behavior of 2-(1-hydroxyethyl)thiamin (1). The equilibrium acidity (pKHA+) of 3 in Me2SO solution was found to be 14.1 ± 0.05, and evidence is presented to indicate that the value in aqueous solution is within ±1 unit of this value. These values are 3 units, or more, lower than previous estimates for the pKHA+ at C-2α of the thiazolium moiety in 1, which were based on kinetic measurements. Related thiazolium cations, where Me, RO, or Ph groups were introduced into the C-2 side chain, were found to have acidities in the 9-15 pKHA+ range.",

author = "Bordwell, {F. G.} and Satish, {A. V.} and Frank Jordan and Rios, {Carlos B.} and {Chitong Chung}, A.",

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T1 - Equilibrium Acidities of 2-Alkylthiazolium Cations at the C-2α Position

AU - Bordwell, F. G.

AU - Satish, A. V.

AU - Jordan, Frank

AU - Rios, Carlos B.

AU - Chitong Chung, A.

PY - 1990/1/1

Y1 - 1990/1/1

N2 - The properties of the 2-(1-methoxyethyl)-3,4-dimethylthiazolium cation (3) and seven related thiazolium cations have been investigated as models for the behavior of 2-(1-hydroxyethyl)thiamin (1). The equilibrium acidity (pKHA+) of 3 in Me2SO solution was found to be 14.1 ± 0.05, and evidence is presented to indicate that the value in aqueous solution is within ±1 unit of this value. These values are 3 units, or more, lower than previous estimates for the pKHA+ at C-2α of the thiazolium moiety in 1, which were based on kinetic measurements. Related thiazolium cations, where Me, RO, or Ph groups were introduced into the C-2 side chain, were found to have acidities in the 9-15 pKHA+ range.

AB - The properties of the 2-(1-methoxyethyl)-3,4-dimethylthiazolium cation (3) and seven related thiazolium cations have been investigated as models for the behavior of 2-(1-hydroxyethyl)thiamin (1). The equilibrium acidity (pKHA+) of 3 in Me2SO solution was found to be 14.1 ± 0.05, and evidence is presented to indicate that the value in aqueous solution is within ±1 unit of this value. These values are 3 units, or more, lower than previous estimates for the pKHA+ at C-2α of the thiazolium moiety in 1, which were based on kinetic measurements. Related thiazolium cations, where Me, RO, or Ph groups were introduced into the C-2 side chain, were found to have acidities in the 9-15 pKHA+ range.

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Equilibrium Acidities of 2-Alkylthiazolium Cations at the C-2α Position

Abstract

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