- Mechanistic Studies of 2-(1-Hydroxyethyl)-2,4,5-trimethyl-3-oxazoline Formation under Low Temperature in 3-Hydroxy-2-butanone/Ammonium Acetate Model Systems
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Volatile compounds formed from the reaction of 3-hydroxy-2-butanone/ammonium acetate at 25, 55 and 85 °C were investigated. Six compounds were characterized by gas chromatography - mass spectrometry (EI and CI). Among the volatile compounds identified, an interesting intermediate compound, 2-(1-hydroxyethyl)-2,4,5-trimethyl-3-oxazoline, was found. 15N-Labeled ammonium acetate was used to confirm the structure of 2-(1-hydroxyethyl)-2,4,5-trimethyl-3-oxazoline. The formation pathway of these volatile compounds was proposed. In these model systems, 2-(1-hydroxyethyl)-2,4,5-trimethyl-3-oxazoline was formed at the reaction temperature below 25 °C. On the other hand, tetramethylpyrazine was the major component when the reaction temperature was higher than 85 °C. The amounts of 2-(1-hydroxyethyl)-2,4,5-trimethyl-3-oxazoline and tetramethylpyrazine increased linearly with the increasing heating time at 55 °C. Protic solvents did not promote 2-(1-hydroxyethyl)-2,4,5-trimethyl-3-oxazoline formation but did favor the formation of tetramethylpyrazine. A kinetic study of 2-(1-hydroxyethyl)-2,4,5-trimethyl-3-oxazoline formation was also performed, and the activation energy was found to be 16.5 kcal/mol.
- Fu, Hui-Yin,Ho, Chi-Tang
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p. 1878 - 1882
(2007/10/03)
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