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{{short description|Organic ring compound (C₃H₄)}} |
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{{Chembox |
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| verifiedrevid = 412508610 |
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| Name = Cyclopropene |
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|verifiedrevid = 442026875 |
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| ImageFileL1 = Cyclopropene.png |
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|ImageFile1 = Cyclopropene 2D skeletal.svg |
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| ImageSizeL1 = 100px |
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|ImageSize1 = 100 |
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| ImageNameL1 = Structural formula of cyclopropene |
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|ImageName1 = Skeletal formula of cyclopropene |
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| ImageFileR1 = Cyclopropene 2D skeletal.svg |
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|ImageFileL2 = Cyclopropene.png |
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| ImageSizeR1 = 100px |
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| ImageNameR1 = Skeletal formula of cyclopropene |
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|ImageNameL2 = Skeletal formula of cyclopropene with implicit hydrogens shown |
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| ImageFile2 = Cyclopropene-3D-balls.png |
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|ImageFileR2 = Cyclopropene-3D-balls.png |
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|ImageNameR2 = Ball and stick model of cyclopropene |
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| ImageSize2 = 120px |
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|PIN = Cyclopropene<ref>{{Cite web|title = cyclopropene - Compound Summary|url = https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=123173&loc=ec_rcs|work = PubChem Compound|publisher = National Center for Biotechnology Information|accessdate = 9 October 2011|location = USA|date = 27 March 2005|at = Identification and Related Records}}</ref> |
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| ImageName2 = Ball-and-stick model of cyclopropene |
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|Section1={{Chembox Identifiers |
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| IUPACName = Cyclopropene |
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|CASNo_Ref = {{cascite|correct|CAS}} |
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| Section1 = {{Chembox Identifiers |
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| CASNo = 2781-85-3 |
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|CASNo = 2781-85-3 |
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|UNII_Ref = {{fdacite|correct|FDA}} |
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| PubChem = 123173 |
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|UNII = 7B8994OHJ0 |
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| SMILES = C1(C=C1) |
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|PubChem = 123173 |
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}} |
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|ChemSpiderID = 109788 |
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| Section2 = {{Chembox Properties |
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|ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} |
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| Formula = C<sub>3</sub>H<sub>4</sub> |
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|MeSHName = cyclopropene |
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| BoilingPtC = -36 |
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| C=3 | H=4}} |
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|SMILES = C1C=C1 |
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|StdInChI = 1S/C3H4/c1-2-3-1/h1-2H,3H2 |
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|StdInChI_Ref = {{stdinchicite|changed|chemspider}} |
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|StdInChIKey = OOXWYYGXTJLWHA-UHFFFAOYSA-N |
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|StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} |
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|Section2={{Chembox Properties |
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|C=3 | H=4 |
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|BoilingPtC = -36 |
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|Section3={{Chembox Thermochemistry |
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|DeltaHc = -2032--2026 kJ mol<sup>−1</sup> |
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|HeatCapacity = 51.9-53.9 J K<sup>−1</sup> mol<sup>−1</sup> |
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'''Cyclopropene''' is an ] with the ] {{carbon}}<sub>3</sub>{{hydrogen}}<sub>4</sub>. It is the simplest isolable ]. It has a ] structure. Because the ring is highly ], cyclopropene is both difficult to prepare and interesting to study.<ref>{{cite journal |authors= Carter, F. L.; Frampton, V. L. |title= Review of the Chemistry of Cyclopropene Compounds |journal= Chemical Reviews |year= 1964 |volume= 64 |pages= 497–525 |doi= 10.1021/cr60231a001 }}</ref> Like ], the carbon ring of cyclopropene is planar. The reduced length of the ] bond compared to an ] causes the angle opposite the double bond to narrow to about 51°<ref>{{cite journal |title= Structure of 3-cyanocyclopropene by microwave spectroscopy and ab initio molecular orbital calculations. Evidence for substituent-ring double bond interactions |authors= Staley, S. W.; Norden, T. D.; Su, C.-F.; Rall, M.; Harmony, M. D. |journal= J. Am. Chem. Soc. |year= 1987 |volume= 109 |issue= 10 |pages= 2880–2884 |doi= 10.1021/ja00244a004 }}</ref> from the 60° angle found in cyclopropane. As with cyclopropane, the carbon–carbon bonding in the ring has increased ]: the alkene carbons use sp<sup>2.68</sup> ] for the ring.<ref>{{cite journal |journal= Tetrahedron |volume= 38 |issue= 5 |year= 1982 |pages= 645–655 |doi= 10.1016/0040-4020(82)80206-8 |title= The geometry of small rings: Molecular geometry of cyclopropene and its derivatives |author= Allen, F. H. }}</ref> |
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'''Cyclopropene''' is an ] with the ] {{chem2|C3H4}}. It is the simplest ]. Because the ring is highly ], cyclopropene is difficult to prepare and highly reactive. This colorless gas has been the subject for many fundamental studies of bonding and reactivity.<ref>{{cite journal |author= Carter, F. L. |author2= Frampton, V. L. |title= Review of the Chemistry of Cyclopropene Compounds |journal= Chemical Reviews |year= 1964 |volume= 64 |issue= 5 |pages= 497–525 |doi= 10.1021/cr60231a001}}</ref> It does not occur naturally, but derivatives are known in some ]s. Derivatives of cyclopropene are used commercially to control ripening of some fruit. |
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==Structure and bonding== |
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The molecule has a ] structure. The reduced length of the ] compared to a ] causes the angle opposite the double bond to narrow to about 51° from the 60° angle found in ].<ref>{{cite journal |title= Structure of 3-cyanocyclopropene by microwave spectroscopy and ab initio molecular orbital calculations. Evidence for substituent-ring double bond interactions |author= Staley, S. W. |author2= Norden, T. D. |author3= Su, C.-F. |author4= Rall, M. |author5= Harmony, M. D. |journal= J. Am. Chem. Soc. |year= 1987 |volume= 109 |issue= 10 |pages= 2880–2884 |doi= 10.1021/ja00244a004 }}</ref> As with cyclopropane, the carbon–carbon bonding in the ring has increased ]: the alkene carbon atoms use sp<sup>2.68</sup> ] for the ring.<ref>{{cite journal |journal= Tetrahedron |volume= 38 |issue= 5 |year= 1982 |pages= 645–655 |doi= 10.1016/0040-4020(82)80206-8 |title= The geometry of small rings: Molecular geometry of cyclopropene and its derivatives |author= Allen, F. H. }}</ref> |
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==Synthesis of cyclopropene and derivatives== |
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==Synthesis of cyclopropene and derivatives== |
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===Early syntheses=== |
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===Early syntheses=== |
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The first confirmed synthesis of cyclopropene, carried out by Dem'yanov and Doyarenko, involved the ] of trimethylcyclopropylammonium hydroxide over platinized clay at 320–330 °C under a CO<sub>2</sub> atmosphere. This reaction produces mainly ] and dimethylcyclopropyl amine, together with about 5% of cyclopropene. Cyclopropene can also be obtained in about 1% yield by thermolysis of the adduct of ] and ]. |
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The first confirmed synthesis of cyclopropene, carried out by Dem'yanov and Doyarenko, involved the ] of trimethylcyclopropylammonium hydroxide over platinized clay at approximately 300 °C. <ref>{{Cite book|last1=Hart|first1=Harold|url=https://books.google.com/books?id=qhwSBQAAQBAJ|title=Advances in Alicyclic Chemistry|last2=Karabatsos|first2=G. J.|publisher=Academic Press Inc.|year=1966|volume=1|location=New York and London|page=55|isbn=9781483224206|language=en}} </ref> This reaction produces mainly ] and dimethylcyclopropyl amine, together with about 5% of cyclopropene. Later Schlatter improved the pyrolytic reaction conditions using platinized ] as a ] at 320–330 °C and obtained cyclopropene in 45% ].<ref>{{Cite journal|last=Schlatter|first=Maurice J.|date=1941-06-01|title=The Preparation of Cyclopropene|url=https://doi.org/10.1021/ja01851a068|journal=Journal of the American Chemical Society|volume=63|issue=6|pages=1733–1737|doi=10.1021/ja01851a068|issn=0002-7863}}</ref> |
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Cyclopropene can also be obtained in about 1% yield by thermolysis of the adduct of ] and ].<ref>{{Cite book|url=https://books.google.com/books?id=GVeGAwAAQBAJ&dq=alder+jacobs+cyclopropene+1528&pg=PA2713|title=Houben-Weyl. Methods of Organic Chemistry – Cyclopropanes, Authors Index, Compound Index|publisher=George Thieme Verlag|year=1997|isbn=978-3-13-101644-7|editor-last=de Meijere|editor-first=Armin|volume=E 17d|location=Stuttgart, New York|pages=2712–2713|language=en}}</ref> |
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===Modern syntheses from allyl chlorides=== |
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===Modern syntheses from allyl chlorides=== |
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] undergoes ] upon treatment with the base ] at 80 °C to produce cyclopropene in about 10% yield.<ref>{{cite journal |authors= Closs, G.L.; Krantz, K.D. |title= A Simple Synthesis of Cyclopropene |journal= Journal of Organic Chemistry |year= 1966 |volume= 31 |pages= 638 |doi= 10.1021/jo01340a534 }}</ref> |
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] undergoes ] upon treatment with the base ] at 80 °C to produce cyclopropene in about 10% yield.<ref>{{cite journal |author= Closs, G.L. |author2= Krantz, K.D. |title= A Simple Synthesis of Cyclopropene |journal= Journal of Organic Chemistry |year= 1966 |volume= 31 |issue= 2 |pages= 638 |doi= 10.1021/jo01340a534 }}</ref> |
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:<math chem>\ce{CH2=CHCH2Cl + NaNH2} \longrightarrow \underset{\text{cyclo-} \atop \text{propene}}{\ce{C3H4}} + \ce{NaCl + NH3}</math> |
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::CH<sub>2</sub>=CHCH<sub>2</sub>Cl + NaNH<sub>2</sub> → C<sub>3</sub>H<sub>4</sub> (cyclopropene) + NaCl + NH<sub>3</sub> |
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The major byproduct of the reaction is ]. Adding allyl chloride to ] in boiling ] over a period of 45–60 minutes produces the targeted compound in about 40% yield with an improvement in purity:<ref name=Binger>{{OrgSynth |author= Binger, P.; Wedermann, P.; Brinker, U. H. |year= 2000 |title= Cyclopropene: A New Simple Synthesis and Its Diels-Alder reaction with Cyclopentadiene |volume= 77 |pages= 254 |collvol= 10 |collvolpages= 231 |prep=v77p0254}}</ref> |
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The major byproduct of the reaction is ]. Adding allyl chloride to ] in boiling ] over a period of 45–60 minutes produces the targeted compound in about 40% yield with an improvement in purity:<ref name=Binger>{{OrgSynth |author= Binger, P. |author2= Wedermann, P. |author3= Brinker, U. H. |year= 2000 |title= Cyclopropene: A New Simple Synthesis and Its Diels-Alder reaction with Cyclopentadiene |volume= 77 |pages= 254 |collvol= 10 |collvolpages= 231 |prep=v77p0254}}</ref> |
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::CH<sub>2</sub>=CHCH<sub>2</sub>Cl + NaN(TMS)<sub>2</sub> → C<sub>3</sub>H<sub>4</sub> (cyclopropene) + NaCl + NH(TMS)<sub>2</sub> |
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:<math chem>\ce{CH2=CHCH2Cl + NaN(TMS)2} \longrightarrow \underset{\text{cyclo-} \atop \text{propene}}{\ce{C3H4}} + \ce{NaCl + NH(TMS)2}</math> |
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1-Methylcyclopropene is synthesized similarly but at room temperature from methallylchloride using ] as the base:<ref>{{cite journal |authors= Clarke, T. C.; Duncan, C. D.; Magid, R. M. |title= An Efficient and Convenient Synthesis of 1-Methylcyclopropene |journal= J. Org. Chem |year= 1971 |volume= 36 |pages= 1320 |doi= 10.1021/jo00808a041 }}</ref> |
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1-Methylcyclopropene is synthesized similarly but at room temperature from methallylchloride using ] as the base:<ref>{{cite journal |author= Clarke, T. C. |author2= Duncan, C. D. |author3= Magid, R. M. |title= An Efficient and Convenient Synthesis of 1-Methylcyclopropene |journal= J. Org. Chem. |year= 1971 |volume= 36 |issue= 9 |pages= 1320–1321 |doi= 10.1021/jo00808a041 }}</ref> |
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::CH<sub>2</sub>=C(CH<sub>3</sub>)CH<sub>2</sub>Cl + LiC<sub>6</sub>H<sub>5</sub> → CH<sub>3</sub>C<sub>3</sub>H<sub>3</sub> (1-methylcylopropene) + LiCl + C<sub>6</sub>H<sub>6</sub> |
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:<math chem>\ce{CH2=C(CH3)CH2Cl + LiC6H5} \longrightarrow \underset{\text{1-methyl-} \atop \text{cyclopropene}}{\ce{CH3C3H3}} + \ce{LiCl + C6H6}</math> |
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===Syntheses of derivatives=== |
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===Syntheses of derivatives=== |
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Treatment of nitrocyclopropanes with ] eliminates the nitrite, giving the respective cyclopropene derivative. The synthesis of purely aliphatic cyclopropenes was first illustrated by the copper-catalyzed additions of carbenes to alkynes. In the presence of a copper sulfate catalyst, ] reacts with acetylenes to give cyclopropenes. 1,2-Dimethylcyclopropene-3-carboxylate arises via this method from ]. Copper has proved to be useful as a catalyst in a variety of cyclopropene syntheses. Copper sulfate and copper dust are among the more popular forms of copper used. |
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Treatment of nitrocyclopropanes with ] eliminates the nitrite, giving the respective cyclopropene derivative. The synthesis of purely aliphatic cyclopropenes was first illustrated by the copper-catalyzed additions of carbenes to alkynes. In the presence of a copper catalyst, ] reacts with acetylenes to give cyclopropenes. 1,2-Dimethylcyclopropene-3-carboxylate arises via this method from ]. Copper, as copper sulfate and copper dust, are among the more popular forms of copper used to promote such reactions. ] has also been used. |
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==Reactions of cyclopropene== |
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==Reactions of cyclopropene== |
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Studies on cyclopropene mainly focus on the consequences of its high ring strain. At 425 °C, cyclopropene isomerizes to ] (propyne). |
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Studies on cyclopropene mainly focus on the consequences of its high ring strain. At 425 °C, cyclopropene isomerizes to ] (propyne). |
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:<chem>C3H4 -> H3CC#CH</chem> |
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:C<sub>3</sub>H<sub>4</sub> → H<sub>3</sub>CC≡CH |
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Attempted fractional distillation of cyclopropene at –36 °C (its predicted boiling point) results in polymerization. The mechanism is assumed to be a free-radical chain reaction, and the product, based on NMR spectra, is thought to be polycyclopropane. |
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Attempted fractional distillation of cyclopropene at –36 °C (its predicted boiling point) results in polymerization. The mechanism is assumed to be a free-radical chain reaction, and the product, based on NMR spectra, is thought to be polycyclopropane. |
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Cyclopropene undergoes the ] with ] to give endo-tricyclooct-6-ene. This reaction is commonly used to check for the presence of cyclopropene, following its synthesis.<ref name=Binger/> |
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Cyclopropene undergoes the ] with ] to give endo-tricyclooct-6-ene. This reaction is commonly used to check for the presence of cyclopropene, following its synthesis.<ref name=Binger/> |
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==Related compounds== |
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==Related compounds== |
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*] is a toxic cyclopropene fatty acid that occurs in cottonseed oil. |
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*] is a toxic cyclopropene fatty acid that occurs in cottonseed oil. |
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*] (1-MCP) is used to slow the ripening in fruits.<ref>{{ cite journal |authors= Beaudry, R.; Watkins, C. |title= Use of 1-MCP on Apples |journal= Perishable Handling Quarterly |year= 2001 |issue= 108 |pages= 12|publisher= ] }}</ref><ref>{{cite journal |journal= Postharvest Biology and Technology |volume= 32 |issue= 2 |month= May |year= 2004 |pages= 193–204 |doi= 10.1016/j.postharvbio.2003.11.009 |title= |
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*] (1-MCP) is used to slow the ripening in fruits.<ref>{{ cite journal |author= Beaudry, R. |author2= Watkins, C. |title= Use of 1-MCP on Apples |journal= Perishable Handling Quarterly |year= 2001 |issue= 108 |pages= 12|publisher= ] }}</ref><ref>{{cite journal |journal= Postharvest Biology and Technology |volume= 32 |issue= 2 |date=May 2004 |pages= 193–204 |doi= 10.1016/j.postharvbio.2003.11.009 |title=Inhibition of ethylene action by 1-methylcyclopropene extends postharvest life of "Bartlett" pears |author= Trinchero, G. D. |author2= Sozzi, G. O. |author3= Covatta, F. |author4= Fraschina, A. A. }}</ref> |
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*]s, ]s, and ]s are boron-, phosphorus-, and silicon-substituted cyclopropenes, with the formula {{chem2|RBC2R'2, RPC2R'2}}, and {{chem2|R2SiC2R'2}}. |
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Inhibition of ethylene action by 1-methylcyclopropene extends postharvest life of "Bartlett" pears |authors= Trinchero, G. D.; Sozzi, G. O.; Covatta, F.; Fraschina, A. A. }}</ref> |
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* ] a class of naturally occurring cyclopropenes. |
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*Borirenes, phosphirenes, and silirenes are boron-, phosphorus-, and silicon-substituted cyclopropenes, with the formula RBC<sub>2</sub>R'<sub>2</sub>, RPC<sub>2</sub>R'<sub>2</sub>, and R<sub>2</sub>SiC<sub>2</sub>R'<sub>2</sub>. |
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==External links== |
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==References== |
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==References== |
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{{Reflist}} |
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<references/> |
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==External links== |
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*{{Commonscatinline|Cyclopropene}} |
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{{cycloalkenes}} |
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{{cycloalkenes}} |
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{{Annulenes}} |
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