:Methylenecyclopropane
{{short description|1=Organic compound, (CH₂)₂C=CH₂}}
{{Chembox
| ImageFile = Methylenecyclopropane with all atoms labeled.png
| ImageSize =
| ImageAlt =
| PIN = Methylidenecyclopropane
| OtherNames =
|Section1={{Chembox Identifiers
| CASNo = 6142-73-0
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = NC8LG5TD4N
| PubChem = 80245
| ChemSpiderID = 72487
| SMILES = C=C1CC1
| InChI = 1/C4H6/c1-4-2-3-4/h1-3H2
| InChIKey = XSGHLZBESSREDT-UHFFFAOYAB
| StdInChI = 1S/C4H6/c1-4-2-3-4/h1-3H2
| StdInChIKey = XSGHLZBESSREDT-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
| Formula = {{chem2|C4H6}}
| MolarMass = 54.09
| Appearance =
| Density = 0.8 g/cm3
| MeltingPt =
| BoilingPtC = 9 to 12
| BoilingPt_notes =
| Solubility = }}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
}}
Methylenecyclopropane is an organic compound with the formula {{chem2|(CH2)2C\dCH2}}. It is a hydrocarbon which, as the name suggests, is derived from the addition of a methylene ({{chem2|\dCH2}}) substituent to a cyclopropane ring. It is a colourless, easily condensed gas that is used as a reagent in organic synthesis.
Synthesis
Methylenecyclopropane can be synthesized via an intramolecular cyclisation reaction from methallyl chloride by treatment with a strong base such sodium amide—sodium tert-butoxide (yield 43%){{ cite journal|author1=Salaun, J. R. |author2=Champion, J. |author3=Conia, J. M. | title = Cyclobutanone from Methylenecyclopropane via Oxaspiropentane | journal = Organic Syntheses | year = 1977 | volume = 57 | pages = 36 | doi=10.15227/orgsyn.057.0036}} or sodium bis(trimethylsilyl)amide with further treatment by sodium tert-butoxide (yield 72%).{{Cite journal |last=Binger |first=Paul |last2=Brinkmann |first2=Axel |last3=Wedemann |first3=Petra |date=2002 |title=Highly Efficient Synthesis of Methylenecyclopropane |url=http://www.thieme-connect.de/DOI/DOI?10.1055/s-2002-33122 |journal=Synthesis |language=en |issue=10 |pages=1344–1346 |doi=10.1055/s-2002-33122 |issn=0039-7881|url-access=subscription }} Sodium tert-butoxide is used to isomerize byproduct 1-methylcyclopropene into methylenecyclopropane.
Reactions
Being a strained and unsaturated molecule methylenecyclopropane undergoes many reactions, especially in the presence of metal catalysts.{{ cite journal |author1=Nakamura, I. |author2=Yamamoto, Y. | title = Transition Metal-Catalyzed Reactions of Methylenecyclopropanes | journal = Advanced Synthesis and Catalysis | year = 2002 | volume = 344 | issue = 2 | pages = 111–129 | doi = 10.1002/1615-4169(200202)344:2<111::AID-ADSC111>3.0.CO;2-0 }}
For example, methylenecyclopropanes can be converted to cyclobutenes in the presence of a platinum catalyst.PtCl2-Catalyzed Rearrangement of Methylenecyclopropanes Alois Fürstner and Christophe Aïssa J. Am. Chem. Soc.; 2006; 128(19) pp 6306 -6307; [https://dx.doi.org/10.1021/ja061392y Abstract] This can be considered similar to the ring expansion seen in vinylcyclopropane rearrangements
:Image:MethylenecyclopropaneIsomerization.png
Substituted methylenecyclopropanes can also be involved in trimethylenemethane cycloaddition reactions.