Description
2-acetylpyrazine is white to pale yellow crystalline powder with a nutty, popcorn, bread-crust odor. It is soluble in water and stable under ordinary conditions. It is used to manufacture many polycyclic compounds and used as useful structures in pharmaceuticals and perfumes. It is a component of the folates (vitamin B compounds) and of the isoalloxazine ring nucleus of flavins. Numerous pyrazine derivatives such as pyrazine polycyclic compounds, alkyl-, alicyclic-, and alkylaryl-substituted compounds, derivatives containing oxygenated functional groups and thio-functional groups in the side-chains are used in biological, drug, flavoring and perfumery industry. 2-acetylpyrazine is used as food additive, commonly used in chocolate and baked goods.
Chemical Properties
Acetylpyrazine is a light yellow to yellow-brownish powder that has a nutty, popcorn, bread crust odor. It is one of the volatile aroma components in popcorn, wheat and rye crusts.
Occurrence
Reported found in guava fruit (Psidium guajava L.), wheaten bread, other types of breads, boiled and cooked
beef, grilled/roasted uncured pork, pork liver, cocoa, coffee, black tea, roasted barley, roasted filbert (Corylus avellano), roasted
peanut (Arachis hypogea), roasted almond (Prunus amygdalus), scallop, filberts, popcorn and sesame oil.
Uses
Acetylpyrazine has been used in synthesis of:
7-heteroaryl-pyrazolo[1,5-a]pyrimidine-3-carboxamides
copper (II) complexes with di-imine ligands
N(4) substituted thiosemicarbazones
Application
Acetylpyrazine has been widely used as an intermediate in the organic synthesis of various heterocyclic derivatives and in coupling reactions, alkylation reactions, and sensitizer ligands because of its good biological and reactive activities. For example, it is a significant reaction intermediate for producing drugs for treating malaria, epilepsy, and Parkinson's disease.
Preparation
synthesis of acetylpyrazine: By the ester condensation of EtO2 C-pyrazine; by dehydrating pyrazynamide with POCI3 and then reacting the resulting 2-cyano-pyrazine with methyl magnesium bromide.
Definition
ChEBI: 2-acetylpyrazine is a pyrazine that is substituted by an acetyl group at position 2. It has been identified as one of the volatile flavor constituents in popcorn, bread crust, vinegar, and potato snacks. It has a role as a flavouring agent. It is an aromatic ketone and a member of pyrazines.
Aroma threshold values
Detection at 62 ppb
Taste threshold values
Taste characteristics at 10 ppm: roasted, nutty, bready, yeasty with popcorn, corn chip nuance
General Description
2-Acetylpyrazine has been identified as one of the volatile flavor constituents in popcorn, wheat and rye bread crust.
Synthesis
General procedure: 2-ethylpyrazine (0.5 mmol), MnOx-N(at)C catalyst (1 mg, pyrolyzed at 600 °C) and tert-butyl hydroperoxide (TBHP, 1.5 mmol, 65% aqueous solution) were added to a 15 mL round bottom flask (RBF). After sealing the flask, the reaction mixture was heated and stirred at 60 °C for 12 hours. Upon completion of the reaction, it was cooled to room temperature and the reaction mixture was diluted with ethyl acetate (4 mL), followed by centrifugation at 10,000 r/min for 1 min to separate the catalyst. The supernatant was collected and the catalyst was washed with ethyl acetate (5 x 4 mL). The supernatant and washings were combined and concentrated to dryness under reduced pressure, and the resulting residue was purified by rapid column chromatography on silica gel (eluent: ethyl acetate/hexane = 1:10, v/v).
References
[1] CHAO-RUI LI. Study on 2-Acetylpyrazine (pyridine-2-acetyl) hydrazone as a fluorescent sensor for Al3+[J]. Journal of Luminescence, 2015, 168: Pages 330-333. DOI:
10.1016/j.jlumin.2015.07.055.
[2] RAMAIYER VENKATRAMAN. Structures of Eight Thio(semi)carbazones Derived from 2-Acetylpyrazine, 2-Acetythiazole and Acetophenone[J]. Journal of Chemical Crystallography, 2009, 39 10. DOI:
10.1007/s10870-009-9541-0.
[3] LIN MAO. Electrochemical Synthesis of Acetylpyrazine[J]. Journal of Electrochemistry, 2021, 9 1: 0. DOI:
10.13208/J.ELECTROCHEM.210706.
[4] https://pubchem.ncbi.nlm.nih.gov/compound/Acetylpyrazine#section=Pharmacology-and-Biochemistry
[5] https://en.wikipedia.org/wiki/Acetylpyrazine
[6] http://www.chemicalland21.com/specialtychem/perchem/2-ACETYLPYRAZINE.htm
