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Pyrazine is a heterocyclic
The Gastaldi synthesis (1921) is another variation:''Amines: Synthesis, Properties and Applications'' Stephen A. Lawrence 2004 Cambridge University Press
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Safety evaluation of food additives – pyrazine derivatives
{{Authority control Simple aromatic rings
aromatic
In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
with the chemical formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
C4H4N2. It is a symmetrical molecule with point group
In geometry, a point group is a mathematical group of symmetry operations ( isometries in a Euclidean space) that have a fixed point in common. The coordinate origin of the Euclidean space is conventionally taken to be a fixed point, and every ...
D2h. Pyrazine is less basic than pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid w ...
, pyridazine and pyrimidine
Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The othe ...
. 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
In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula . The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of th ...
and decrease nitric oxide
Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its ...
production in human Granulocytes.
Synthesis
Many methods exist for theorganic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...
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
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous ...
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.
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The Gastaldi synthesis (1921) is another variation:''Amines: Synthesis, Properties and Applications'' Stephen A. Lawrence 2004 Cambridge University Press
:
See also
* Alkylpyrazines *Benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...
, an analog without the nitrogen atoms
* Methoxypyrazines
* Pyridazine, an analog with the second nitrogen atom in position 2
* Pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid w ...
, an analog with only one nitrogen atom
* Pyrimidine
Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The othe ...
, an analog with the second nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
atom
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons.
Every solid, liquid, gas, a ...
in position 3
* Simple aromatic rings
References
External links
Safety evaluation of food additives – pyrazine derivatives
{{Authority control Simple aromatic rings