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

Hui Yin Fu, Chi Tang Ho

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4 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)1878-1882
Number of pages5
JournalJournal of agricultural and food chemistry
Volume45
Issue number5
DOIs
StatePublished - May 1997

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

Keywords

  • 2-(1-Hydroxyethyl)-2,4,5-trimethyl-3-oxazoline
  • Activation energy
  • GC-MS
  • Kinetic study

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