Dicyanoacetylene
(also carbon subnitride
, IUPAC but-2-ynedinitrile), NC
4N, is a compound of
carbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
and
nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
. It has a linear structure, NCCCCN, with alternating triple and single
covalent bondA covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, or between atoms and other covalent bonds...
s. In other words, it is
acetyleneAcetylene is the chemical compound with the formula HC
2H. It is a hydrocarbon and the simplest alkyne. This colourless gas is widely used as a fuel and a chemical building block...
with the two hydrogen atoms replaced by
cyanideA cyanide is any chemical compound that contains the cyano group , which consists of a carbon atom triple-bonded to a nitrogen atom. Inorganic cyanides are hydrogen cyanide salts in which cyanide is generally the anion CN
-. Organic compounds that have a -C≡N functional group bonded to...
groups.
At room temperature, dicyanoacetylene is a clear liquid. Because of its high endothermic heat of formation, it can explode to carbon powder and nitrogen gas, and it burns in oxygen with a bright blue-white flame at a temperature of 5260 K (4990 °C, 9010 °F), which is the hottest flame of any chemical, according to
Guinness World RecordsGuinness World Records, known until 2000 as The Guinness Book of Records , is a reference book published annually, containing an internationally recognised...
.
Dicyanoacetylene is a powerful dienophile because the cyanide groups are electron-withdrawing, so it is a useful reagent for
Diels-Alder reactionThe Diels-Alder reaction is an organic chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. The reaction can proceed even if some of the atoms in the newly-formed ring are not carbon...
s with unreactive dienes.
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Dicyanoacetylene
(also carbon subnitride
, IUPAC but-2-ynedinitrile), NC
4N, is a compound of
carbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
and
nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
. It has a linear structure, NCCCCN, with alternating triple and single
covalent bondA covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, or between atoms and other covalent bonds...
s. In other words, it is
acetyleneAcetylene is the chemical compound with the formula HC
2H. It is a hydrocarbon and the simplest alkyne. This colourless gas is widely used as a fuel and a chemical building block...
with the two hydrogen atoms replaced by
cyanideA cyanide is any chemical compound that contains the cyano group , which consists of a carbon atom triple-bonded to a nitrogen atom. Inorganic cyanides are hydrogen cyanide salts in which cyanide is generally the anion CN
-. Organic compounds that have a -C≡N functional group bonded to...
groups.
At room temperature, dicyanoacetylene is a clear liquid. Because of its high endothermic heat of formation, it can explode to carbon powder and nitrogen gas, and it burns in oxygen with a bright blue-white flame at a temperature of 5260 K (4990 °C, 9010 °F), which is the hottest flame of any chemical, according to
Guinness World RecordsGuinness World Records, known until 2000 as The Guinness Book of Records , is a reference book published annually, containing an internationally recognised...
.
As a reagent in organic chemistry
Dicyanoacetylene is a powerful dienophile because the cyanide groups are electron-withdrawing, so it is a useful reagent for
Diels-Alder reactionThe Diels-Alder reaction is an organic chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. The reaction can proceed even if some of the atoms in the newly-formed ring are not carbon...
s with unreactive dienes. It even adds to the
aromaticIn organic chemistry, the structures of some rings of atoms are unexpectedly stable. Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone...
compound
dureneDurene, or 1,2,4,5-tetramethylbenzene, is an aromatic hydrocarbon used as a solvent. It is also an intermediate in the manufacture of pyromellitic acid, which is used for manufacturing curing agents, adhesives and coating materials...
(1,2,4,5-tetramethylbenzene) to form a substituted bicyclooctatriene. Only the most reactive of dienophiles can attack aromatic dienes.
In outer space
Solid dicyanoacetylene has been detected in
TitanTitan , or Saturn VI, is the largest moon of Saturn, the only moon known to have a dense atmosphere,
and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
's atmosphere by
infrared spectroscopyInfrared spectroscopy is the subset of spectroscopy that deals with the infrared region of the electromagnetic spectrum. It covers a range of techniques, the most common being a form of absorption spectroscopy. As with all spectroscopic techniques, it can be used to identify compounds or...
. As the seasons change on Titan, the NC
4N condenses and evaporates in a cycle, which allows scientists on Earth to study Titanian meteorology.
, the detection of dicyanoacetylene in the
interstellar mediumIn astronomy, the interstellar medium is the gas and dust that pervade interstellar space: the matter that exists between the star systems within a galaxy. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
has been impossible, because its symmetry means it has no
rotational microwave spectrumRotational spectroscopy or microwave spectroscopy studies the absorption and emission of electromagnetic radiation by molecules associated with a corresponding change in the rotational quantum number of the molecule...
. However, similar asymmetric molecules like cyanoacetylene have been observed, and it is suspected that advances in astronomical infrared spectroscopy will lead to the detection of interstellar NC
4N.