Cyclobutadiene
IUPAC name	1,3-Cyclobutadiene
Other names	Cyclobutadiene [4]Annulene
Identifiers
CAS number	[1120-53-2]
SMILES	C1=CC=C1
Properties
Molecular formula	C4H4
Molar mass	52. IUPAC Nomenclature is a system of naming Chemical compounds and of describing the science of Chemistry in general CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Molar mass, symbol M, is the Mass of one mole of a substance ( Chemical element or Chemical compound) 07 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Cyclobutadiene is the smallest [n]-annulene ([4]-annulene), an extremely unstable hydrocarbon having a lifetime shorter than five seconds in the free state. In Chemistry, the standard state of a material is its state at 1 bar (100 Kilopascals exactly Annulenes are completely conjugated monocyclic Hydrocarbons They have the general formula CnHn (n is an even number or CnHn+1 In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon. It has chemical formula C₄H₄ and a rectangular structure verified by infrared studies. A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 In Geometry, a rectangle is defined as a Quadrilateral where all four of its angles are Right angles A rectangle with vertices ABCD would be denoted as This is in contrast to the square geometry predicted by simple Hückel theory. Classification A square (regular Quadrilateral) is a special case of a Rectangle as it has four right angles and equal parallel sides Though it has alternating single and double bonds, it fails Hückel's rule, because its ring has 4 π-electrons, and 4 is not twice an odd number. In Organic chemistry, Hückel's rule estimates whether a Planar ring Molecule will have Aromatic properties In Mathematics an even Integer, that is a number that is divisible by 2 is called evenly even or doubly even if it is a multiple Some cyclobutadiene-metal compounds are stable because the metal atom provides 2 more electrons to the system.

The pi electron energy of cyclobutadiene is higher than that of its open-chain counterpart, 1,3-butadiene, and it is therefore said to be anti-aromatic rather than aromatic. In Chemistry, pi bonds ( π bonds) are covalent Chemical bonds where two lobes of one involved electron orbital overlap two lobes Recent studies on cyclobutadiene show that it has a rectangular structure as opposed to a square structure and two different 1,2-dideuterio-1,3-cyclobutadiene stereoisomers. This indicates that the pi electrons are localized and therefore not considered to be antiaromatic. In Chemistry, pi bonds ( π bonds) are covalent Chemical bonds where two lobes of one involved electron orbital overlap two lobes Antiaromatic Molecules are Cyclic systems containing alternating single and Double bonds where the Pi electron energy of antiaromatic compounds However it is far from stable, it is highly reactive and has a very short lifetime. Cyclobutadiene dimerizes by a Diels-Alder reaction at 35 K. A dimer is a Chemical or Biological entity consisting of two subunits called Monomers which are held together by either Intramolecular forces The Diels-Alder reaction is an Organic chemical reaction (specifically a Cycloaddition) between a conjugated Diene and a substituted Alkene,

Synthesis

After numerous attempts, it was first synthesized in 1965 by Rowland Pettit of the University of Texas, although he could not isolate it. Year 1965 ( MCMLXV) was a Common year starting on Friday (link will display full calendar of the 1965 Gregorian calendar. Cyclobutadiene can be generated through degradation from a cyclobutadiene metal compound for example C₄H₄Fe(CO)₃ with ammonium cerium(IV) nitrate. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Ceric ammonium nitrate, or in lab jargon "CAN" is the Chemical compound with the formula ( NH4)2Ce(NO36 This cyclobutadieneiron tricarbonyl complex was prepared from Fe₄(CO)₉ and cis-dichlorocyclobutene in a double dehydrohalogenation. Cyclobutadieneiron tricarbonyl or (C4H4Fe(CO3 is an Organometallic complex of Cyclobutadiene and an Iron Metal carbonyl Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Dehydrohalogenation is an Organic chemistry reaction from which an Alkene is obtained from an Alkyl halide. ^[1][2]

Cyclobutadiene when liberated from the iron complex reacts with electron-deficient alkynes to a Dewar benzene:^[3]

The Dewar benzene converts to dimethyl phthalate on heating at 90°C. Alkynes are Hydrocarbons that have at least one Triple bond between two Carbon atoms with the formula CnH2n-2. Dewar benzene or bicyclohexa-25-diene is the Bicyclic Isomer of Benzene with the molecular formula C6H6 Phthalic acid ( IUPAC Systematic name: benzene-12-dicarboxylic acid) is an Aromatic Dicarboxylic acid, with formula C6H4(COOH2

One cyclobutadiene derivative is also accessible through a [2+2]cycloaddition of a di-alkyne. A cycloaddition is a Pericyclic Chemical reaction, in which two π bonds are lost and two σ bonds are gained the resulting reaction is a Alkynes are Hydrocarbons that have at least one Triple bond between two Carbon atoms with the formula CnH2n-2. In this particular reaction the trapping reagent is 2,3,4,5-tetraphenylcyclopenta-2,4-dienone and one of the final products (after expulsion of carbon monoxide) a cyclooctatetraene:^[4]

See also

• Cyclobutene
• Butadiene

References

1. ^ Cyclobutadiene- and Benzocyclobutadiene-Iron Tricarbonyl Complexes G. In Chemistry, a chemical trap is a Chemical compound that is used to detect a certain Molecule when the Concentration of this Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. 1357-Cyclooctatetraene ( COT) is an unsaturated Derivative of Cyclooctane, with the formula C8H8 Cyclobutene is a Cycloalkene with Chemical formula 46 and CAS number 822-35-5 F. Emerson, L. Watts, R. Pettit; J. Am. Chem. Soc.; 1965; 87(1); 131-133. The Journal of the American Chemical Society (usually abbreviated as J First Page
2. ^ Iron, tricarbonyl (η4-1,3-cyclobutadiene)- R. Pettit and J. Henery Organic Syntheses, Coll. Organic Syntheses is a Scientific journal that since 1921 has provided the Chemistry community with annual collections of detailed and checked procedures Vol. 6, p. 310 (1988); Vol. 50, p. 21 (1970) Link
3. ^ Cyclobutadiene L. Watts, J. D. Fitzpatrick, R. Pettit J. Am. Chem. Soc.; 1965; 87(14); 3253-3254. The Journal of the American Chemical Society (usually abbreviated as J Abstract
4. ^ Revisit of the Dessy-White Intramolecular Acetylene-Acetylene [2 + 2] Cycloadditions Chung-Chieh Lee, Man-kit Leung, Gene-Hsiang Lee, Yi-Hung Liu, and Shie-Ming Peng J. Org. Chem.; 2006; 71(22) pp 8417 - 8423; (Article) doi:10.1021/jo061334v

The Journal of Organic Chemistry (abbreviated as J Org Chem or JOC) is a Scientific journal for original contributions of fundamental A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.

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