Pyrazine
Pyrazine is a heterocyclic aromatic organic compound with the chemical formula CHN. It is a symmetrical molecule with point group D. Pyrazine is less basic than pyridine, pyridazine and pyrimidine. It is a ""deliquescent crystal or wax-like solid with a pungent, sweet, corn-like, nutty odour"". Pyrazine and a variety of alkylpyrazines are flavor and aroma compounds found in baked and roasted goods. Tetramethylpyrazine (also known as ligustrazine) is reported to scavenge superoxide anion and decrease nitric oxide production in human polymorphonuclear leukocytes. Synthesis. Many methods exist for the organic synthesis of pyrazine and its derivatives. Some of  these are among the oldest synthesis reactions still in use. In the Staedel–Rugheimer pyrazine synthesis (1876) 2-chloroacetophenone is reacted with ammonia to the amino ketone, then condensed and then oxidized to a pyrazine. A variation is the Gutknecht pyrazine synthesis (1879) also based on this selfcondensation, but differing in the way the alpha-ketoamine is synthesised. The Gastaldi synthesis (1921) is another variation: