Pyrazine
Encyclopedia
Pyrazine is a heterocyclic aromatic organic compound
with the chemical formula
C4H4N2.
Pyrazine is a symmetrical molecule with point group
D2h. Derivatives like phenazine
are well known for their antitumor, antibiotic and diuretic activity. Pyrazine is less basic in nature than pyridine
, pyridazine
and pyrimidine
. Tetramethylpyrazine (also known as ligustrazine) is reported to scavenge superoxide anion and decrease nitric oxide production in human polymorphonuclear leukocytes. Tetramethylpyrazine is also a component of some herbs in traditional Chinese medicine
.
of pyrazine and derivatives and some of them very old.
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 chlorine compound in the above method is a lachrymatory agent
)
The Gastaldi synthesis (1921) is another variation :
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
with the chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
C4H4N2.
Pyrazine is a symmetrical molecule with point group
Point group
In geometry, a point group is a group of geometric symmetries that keep at least one point fixed. Point groups can exist in a Euclidean space with any dimension, and every point group in dimension d is a subgroup of the orthogonal group O...
D2h. Derivatives like phenazine
Phenazine
Phenazine , also called azophenylene, dibenzo-p-diazine, dibenzopyrazine, and acridizine, is a dibenzo annulated pyrazine and the parent substance of many dyestuffs, such as the eurhodines, toluylene red, indulines and safranines.-Synthesis:A classic method for the synthesis of phenazine is the...
are well known for their antitumor, antibiotic and diuretic activity. Pyrazine is less basic in nature than pyridine
Pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...
, pyridazine
Pyridazine
Pyridazine is a heteroaromatic organic compound with the molecular formula C4H4N2, sometimes called 1,2-diazine. It contains a six-membered ring with two adjacent nitrogen atoms. It is a colorless liquid with a boiling point of 208 °C....
and pyrimidine
Pyrimidine
Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring...
. Tetramethylpyrazine (also known as ligustrazine) is reported to scavenge superoxide anion and decrease nitric oxide production in human polymorphonuclear leukocytes. Tetramethylpyrazine is also a component of some herbs in traditional Chinese medicine
Traditional Chinese medicine
Traditional Chinese Medicine refers to a broad range of medicine practices sharing common theoretical concepts which have been developed in China and are based on a tradition of more than 2,000 years, including various forms of herbal medicine, acupuncture, massage , exercise , and dietary therapy...
.
Synthesis
Many methods exist for the organic synthesisOrganic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
of pyrazine and derivatives and some of them very old.
In the Staedel-Rugheimer pyrazine synthesis (1876) 2-chloroacetophenone is reacted with ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
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 chlorine compound in the above method is a lachrymatory agent
Lachrymatory agent
Tear gas, formally known as a lachrymatory agent or lachrymator , is a non-lethal chemical weapon that stimulates the corneal nerves in the eyes to cause tears, pain, and even blindness...
)
The Gastaldi synthesis (1921) is another variation :
See also
- PyrimidinePyrimidinePyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring...
, an analog with the second nitrogenNitrogenNitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
atomAtomThe atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
in position 3. - PyridazinePyridazinePyridazine is a heteroaromatic organic compound with the molecular formula C4H4N2, sometimes called 1,2-diazine. It contains a six-membered ring with two adjacent nitrogen atoms. It is a colorless liquid with a boiling point of 208 °C....
, an analog with the second nitrogen atom in position 2. - PyridinePyridinePyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...
, an analog with only one nitrogen atom. - BenzeneBenzeneBenzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
, an analog without the nitrogen atoms. - Simple aromatic ringSimple aromatic ringSimple aromatic rings, also known as simple arenes or simple aromatics, are aromatic organic compounds that consist only of a conjugated planar ring system with delocalized pi electron clouds. Many simple aromatic rings have trivial names. They are usually found as substructures of more complex...
s - MethoxypyrazinesMethoxypyrazinesMethoxypyrazines are a class of chemical compounds that produce odors. The odors tend to be undesirable, as in the case of certain wines, or as in the case of the Asian Lady Beetle which produces isopropyl methoxy pyrazine . They have also been identified as additives in cigarette manufacture...