Pyrazines refer to heterocyclic compounds containing two nitrogen atoms on the 1,4 sites of benzene ring. Pyrazine, pyrimidine and pyridazine are isomerides to each other. Similar with pyridine, pyrazines are weakly aromatic and less prone to electrophilic substitution reaction, but easily reactive with nucleophilic reagent. Halogen or hydrogen on the methyl group become active after the hydrogen on carbon atom is substituted with methyl or halogen. Pure pyrazine can hardly be found in nature, but its residue exists in the pterin structure of folic acid. Pyrazines are prepared through gas phase catalytic dehydrogenation of ethanolamine in industry.
Pyrazine derivatives are multifunctional, e.g. dibenzo pyrazine is an important dye, phenazine is widely known for its anti-tumor, antibacterial and diuretic properties and tetramethylpyazine has been reported to be able to catch the superoxide anions and reduce human granulocyte’s production of nitrogen oxides. hexahydropyrazine (also as piperazine) citrate is a commonly used animal repellents, particularly effective against roundworms. 2,5-Dioxopiperazine is an agent used in the preparation of peptides.
Pyrazine spices generally have an aroma of roasted food, nuts, popcorn and coffee; although they don’t have the flavor of meat, they are commonly used in meat flavor spices recipe to enhance and enrich the overall barbecue flavor.