Mechanistic Studies of Tetramethylpyrazine Formation under Weak Acidic Conditions and High Hydrostatic Pressure

Abstract

A significant enhancement of the tetramethylpyrazine (TMP) formation at high pressure was observed in the 3-hydroxy-2-butanone/ammonium acetate model system. In a water system, the activation volume of TMP formation under high pressure was found to be −6.82 mL/mol. A mechanism was proposed to elucidate the formation of TMP under a weak acidic condition and high hydrostatic pressure. Solvents such as propylene glycol (PG), glycerol, methanol, ethanol, propanol, and butanol were found to enhance TMP formation. Kinetic analyses indicated that TMP formation in aqueous, 80% PG, and ethanol systems followed pseudo-zero-order reaction kinetics. The activation energies were found to be 18.84 ± 1.3, 14.19 ± 7.1, and 13.09 ± 4.7 kcal/mol, respectively. The intermediate of TMP formation was characterized as tetramethyldihdyropyrazine using gas chromatography−mass spectrometry. A 15N-labeled ammonium acetate/3-hydroxy-2-butanone model system was used to confirm the incorporation of a nitrogen atom in the molecule of tetramethyldihydropyrazine. Hydrogen acceptors such as nicotinamide adenine dinucleotide and flavin adenine dinucleotide were found to increase TMP formation, and the formation of TMP from tetramethyldihydropyrazine through dehydrogenation was shown. Keywords: Pyrazine formation; high hydrostatic pressure; kinetics

High-yield fermentative preparation of tetramethylpyrazine by Bacillus sp. using an endogenous precursor approach

“…Similarly, Nakashimada et al [23] increased HB formation with a high air supply when investigating the eVect of oxygen supply on diol fermentation by Paenibacillus polymyxa ATCC 12321 (formerly classiWed as a member of the Bacillus genus). Tetramethyldihydropyrazine has been characterized as an intermediate in the transformation of the corresponding TTMP in a redox reaction [10]; as such, this reaction may be accelerated by an increased dissolved oxygen level.…”

Combined Effects of a Buffer and Solvent on Tetramethylpyrazine Formation in a 3-Hydroxy-2-butanone/Ammonium Hydroxide System

“…Salts of weak acids may act as catalysts in the formation of TMP. 15 ) To look with more detail into the formation mechanism for TMP in the buffer system. the pH change in models with different concentrations of phosphate was investigated.…”

Mechanistic Studies on the Formation of Thiazolidine and Structurally Related Thiazines in a Cysteamine/2,3-Butanedione Model System

“…The formation of 2-acetyl-2methylthiazolidine was found to be independent of azodicarbonamide as shown in Table 3. The redox reaction seems to lead to the conversion of 2-acetyl-2,3,5,6-tetrahydro-1,4-thiazine to 5-acetyl-2,3-dihydro-1,4-thiazine via a proton-transfer reaction similar to that in the conversion of tetramethyldihydropyrazine to tetramethylpyrazine (Huang et al, 1996). The redox reaction has been proposed by Huyghues-Despointes and Yaylayan (1996) in a Maillard model system composed of D-glucose and proline.…”

“…In a reaction medium with a phosphate buffer, the nucleophilic amino group on a cysteamine molecule tends to attack the positively induced carbonyl carbon on the 2,3-butanedione molecule. The proton transfer facilitated by a phosphate ion not only makes the hydroxyl group a better leaving group, which is converted to a molecule of water, but also leads to the elimination of the hydrogen atom on the nitrogen atom (Huang et al, 1996). The dehydration and proton transfer gives a Schiff base.…”