| Revision as of 22:57, 22 March 2011 editCheMoBot (talk | contribs)Bots141,565 edits Updating {{chembox}} (no changed fields - updated 'UNII_Ref', 'StdInChI_Ref', 'StdInChIKey_Ref', 'ChEMBL_Ref', 'KEGG_Ref') per Chem/Drugbox validation (report [[Wikipedia_talk:WikiProject_Chemica← Previous edit |
Latest revision as of 11:20, 3 January 2025 edit undoNucleus hydro elemon (talk | contribs)Extended confirmed users3,351 edits explicit double bonds |
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{{Chembox |
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{{Chembox |
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|verifiedrevid = 396320598 |
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| verifiedrevid = 420229237 |
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|Reference=<ref name="sgma" /> |
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| Reference =<ref name="sgma" /> |
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|Name=''cis''-Cycloheptene |
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|ImageFile=Cycloheptene.svg |
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| Name =''cis''-Cycloheptene |
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| ImageFile =Cycloheptene.svg |
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|ImageSize=100px |
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| ImageSize =100px |
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|ImageFile2=Cis-cycloheptene3D.png |
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| ImageFile2 =Cis-cycloheptene3D.png |
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|ImageSize2=200px |
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| ImageSize2 = |
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|IUPACName=(''Z'')-Cycloheptene |
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|OtherNames=''cis''-Cycloheptene |
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| PIN =Cycloheptene |
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| OtherNames =''cis''-Cycloheptene |
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|Section1= {{Chembox Identifiers |
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|Section1={{Chembox Identifiers |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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|ChemSpiderID = 11857 |
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| ChemSpiderID = 11857 |
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|InChI = 1/C7H12/c1-2-4-6-7-5-3-1/h1-2H,3-7H2 |
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| InChI = 1/C7H12/c1-2-4-6-7-5-3-1/h1-2H,3-7H2 |
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|InChIKey = ZXIJMRYMVAMXQP-UHFFFAOYAQ |
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| InChIKey = ZXIJMRYMVAMXQP-UHFFFAOYAQ |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI = 1S/C7H12/c1-2-4-6-7-5-3-1/h1-2H,3-7H2 |
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| StdInChI = 1S/C7H12/c1-2-4-6-7-5-3-1/h1-2H,3-7H2 |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey = ZXIJMRYMVAMXQP-UHFFFAOYSA-N |
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| StdInChIKey = ZXIJMRYMVAMXQP-UHFFFAOYSA-N |
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|CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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|CASNo=628-92-2 |
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| CASNo =628-92-2 |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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|PubChem=12363 |
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| UNII = KRY3SY05AH |
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|SMILES = C\1=C\CCCCC/1 |
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| PubChem =12363 |
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| SMILES = C\1=C\CCCCC/1 |
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|Section2= {{Chembox Properties |
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|Section2={{Chembox Properties |
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| Formula=C<sub>7</sub>H<sub>12</sub> |
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| Formula =C<sub>7</sub>H<sub>12</sub> |
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| MolarMass=96.17 g/mol |
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| MolarMass =96.17 g/mol |
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| Appearance= |
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| Appearance = |
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| Density=0.824 g/cm<sup>3</sup> |
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| Density =0.824 g/cm<sup>3</sup> |
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| MeltingPt= |
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| MeltingPt = |
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| BoilingPt=112-114.7 °C |
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| BoilingPtC = 112 to 114.7 |
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|Section3= {{Chembox Hazards |
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| FlashPt= |
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|Section3={{Chembox Hazards |
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| MainHazards = |
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| FlashPt = |
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'''Cycloheptene''' is a 7-membered ] with a flash point of -6 C°. It is a raw material in ] and a ] in polymer synthesis. Cycloheptene can exist as either the ]- or the ''trans''-isomer. |
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'''Cycloheptene''' is a 7-membered ] with a flash point of −6.7 °C. It is a raw material in ] and a ] in polymer synthesis. Cycloheptene can exist as either the ]- or the ''trans''-isomer. |
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|align="center"|''cis''-Cycloheptene |
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|align="center"|''trans''-Cycloheptene |
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== ''trans''-Cycloheptene == |
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== ''trans''-Cycloheptene == |
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With cycloheptene, the ''cis''-isomer is always assumed but the ''trans''-isomer does also exist. One procedure for the ] of ''trans''-cycloheptene is by singlet ] of cis-cycloheptene with ] and ] at -35°C.<ref name="Squillacote" /> The ] in the ''trans'' isomer is very ].<ref name="cain" /> Part of the ] is relieved by ] of the alkene carbons, the pyramidalization angle is estimated at 37° (compared to a zero angle in an unstrained alkene) and the ] misalignment is 30.1°.<ref name="Squillacote" /> Because the barrier for rotation of the double bond in ] is approximately 65 ]/] (270 ]/mol) and can only be lowered by the estimated strain energy of 30 kcal/mol (125 kJ/mol) present in the ''trans''-isomer, ''trans''-cycloheptene should be a stable molecule just as its homologue ]. In fact, it is not; and unless the temperature is kept very low, quick isomerization to the ''cis''-isomer takes place. In a 2005 publication, it is argued that ''trans''-cycloheptene isomerization occurs by an alternative lower energy pathway.<ref name="Squillacote" /> Based on the experimentally observed ] for isomerization, two ''trans''-cycloheptene molecules in the proposed pathway first form a ] ]. The two ] radical rings then untwist to an unstrained conformation and in the final step the dimer is cleaved again into two ''cis''-cycloheptene molecules. Note that the photoisomerization of ] to ] with ] is also bimolecular. |
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With cycloheptene, the ''cis''-isomer is always assumed but the ''trans''-isomer does also exist. One procedure for the ] of ''trans''-cycloheptene is by singlet ] of cis-cycloheptene with ] and ] at −35 °C.<ref name="Squillacote" /> The ] in the ''trans'' isomer is very ].<ref name="cain" /> The directly attached atoms on a simple alkene are all coplanar. In ''trans''-cycloheptene, however, the size of the ring makes it impossible for the alkene and its two attached carbons to have this geometry because the remaining three carbons could not reach far enough to close the ring (see also ]). There would have to be unusually large angles (]), unusually long bond-lengths, or the atoms of the alkane-like loop would collide with the alkene part (]). Part of the strain is relieved by ] and their rotation relative to each other. The pyramidalization angle is estimated at 37° (compared to an angle of 0° for an atom with normal trigonal–planar geometry) and the ] misalignment is 30.1°.<ref name="Squillacote" /> Because the barrier for rotation of the double bond in ] is approximately 65 ]/] (270 ]/mol) and can only be lowered by the estimated strain energy of 30 kcal/mol (125 kJ/mol) present in the ''trans''-isomer, ''trans''-cycloheptene should be a stable molecule just as its homologue ]. In fact, it is not: unless the temperature is kept very low, rapid isomerization to the ''cis''-isomer takes place. The ''trans''-cycloheptene isomerization mechanism is not simple alkene-bond rotation, but rather an alternative lower energy pathway.<ref name="Squillacote" /> Based on the experimentally observed ] for isomerization, two ''trans''-cycloheptene molecules in the proposed pathway first form a ] ]. The two ] radical rings then untwist to an unstrained conformation, and finally the dimer fragments back into two ''cis''-cycloheptene molecules. Note that the photoisomerization of ] to ] with ] is also bimolecular. |
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== References == |
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== References == |
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{{Reflist|refs= |
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{{Reflist|refs= |
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<ref name="sgma"> at ]</ref> |
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<ref name="sgma"> at ]</ref> |
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<ref name="cain">D. Cain, D. M. Pawar and E. A. Noe, "Conformational studies of trans-cycloheptene, trans-cycloheptene oxide, and trans-bicyclo octane by ab initio calculations", ''Journal of Molecular Structure: THEOCHEM'', volume 674, issues 1-3, April 2004, Pages 251-255</ref> |
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<ref name="cain">{{cite journal |first1= D. |last1= Cain |first2= D. M. |last2= Pawar |first3= E. A. |last3= Noe |title= Conformational studies of ''trans''-cycloheptene, ''trans''-cycloheptene oxide, and ''trans''-bicyclooctane by ab initio calculations |journal= ] |volume= 674 |issue= 1–3 |date=April 2004 |pages= 251–255 |doi= 10.1016/S0166-1280(03)00367-1 }}</ref> |
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<ref name="Squillacote">Michael E. Squillacote, James DeFellipis, and Qingning Shu ''How Stable Is trans-Cycloheptene?'' ]; '''2005'''; 127(45) pp 15983 - 15988; (Article) DOI: 10.1021/ja055388i |
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<ref name="Squillacote">{{cite journal |first= Michael E. |last1= Squillacote |first2= James |last2= DeFellipis |first3= Qingning |last3= Shu |title= How Stable Is ''trans''-Cycloheptene? |journal= ] |year= 2005 |volume= 127 |issue= 45 |pages= 15983–15988 |doi= 10.1021/ja055388i }}</ref> |
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