cycloheptatriene

{{chembox

|Watchedfields=changed

|verifiedrevid=443548678

|ImageFileL1=Cyclohepta-1,3,5-triene 200.svg

|ImageFileR1=Cycloheptatriene-3D-balls.png|PIN=Cyclohepta-1,3,5-triene{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = The Royal Society of Chemistry | date = 2014 | location = Cambridge | page = 223 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4}}|OtherNames=1,3,5-Cycloheptatriene
1H-[7]Annulene
CHT
Tropilidene|Section1={{Chembox Identifiers

|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

|ChemSpiderID = 10534

|InChI = 1/C7H8/c1-2-4-6-7-5-3-1/h1-6H,7H2

|InChIKey = CHVJITGCYZJHLR-UHFFFAOYAI

|StdInChI_Ref = {{stdinchicite|correct|chemspider}}

|StdInChI = 1S/C7H8/c1-2-4-6-7-5-3-1/h1-6H,7H2

|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

|StdInChIKey = CHVJITGCYZJHLR-UHFFFAOYSA-N

|CASNo_Ref = {{cascite|correct|CAS}}

|CASNo = 544-25-2

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = P58Q106NTF

|ChEBI_Ref = {{ebicite|correct|EBI}}

|ChEBI = 37519

|EINECS = 208-866-3

|UNNumber = 2603

|SMILES = C1=C\C/C=C\C=C1

|PubChem = 11000

|Gmelin = 1943

|Beilstein = 506066

}}|Section2={{Chembox Properties

|C=7 | H=8

|Appearance = Colourless liquid

|Density = 0.888 g/mL at 25 °C

|MeltingPtC = -80

|BoilingPtC = 116

|pKa = 36

|Solubility = Insoluble in water

}}|Section3={{Chembox Hazards

|GHSPictograms = {{GHS02}}{{GHS06}}{{GHS07}}{{GHS08}}

|GHSSignalWord = Danger

|HPhrases = {{H-phrases|225|301|304|311|315|319|335}}

|PPhrases = {{P-phrases|210|233|240|241|242|243|261|264|270|271|280|301+310|302+352|303+361+353|304+340|305+351+338|312|321|322|330|331|332+313|337+313|361|362|363|370+378|403+233|403+235|405|501}}

}}

}}

Cycloheptatriene (CHT) is an organic compound with the formula C₇H₈. It is a closed ring of seven carbon atoms joined by three double bonds (as the name implies) and four single bonds. This colourless liquid has been of recurring theoretical interest in organic chemistry. It is a ligand in organometallic chemistry and a building block in organic synthesis. Cycloheptatriene is not aromatic, as reflected by the nonplanarity of the methylene bridge ({{chem2|\sCH2\s}}) with respect to the other atoms; however the related tropylium cation is, rendering the compound relatively suspectible to oxidation.

==Synthesis==

Albert Ladenburg first generated cycloheptatriene in 1881 by the decomposition of tropine.{{cite journal| author = A. Ladenburg| title = Die Constitution des Atropins| journal = Justus Liebig's Annalen der Chemie| volume = 217| issue = 1| pages = 74–149| year = 1883| doi= 10.1002/jlac.18832170107| author-link = Albert Ladenburg| url = https://zenodo.org/record/1427383}}{{cite journal| author = A. Ladenburg| title = Die Zerlegung des Tropines| journal = Berichte der Deutschen Chemischen Gesellschaft| volume = 14| issue =2| pages = 2126–2131| year = 1881| url= http://gallica.bnf.fr/ark:/12148/bpt6k906939/f537.chemindefer| doi = 10.1002/cber.188101402127| author-link = Albert Ladenburg}} The structure was finally proven by the synthesis of Richard Willstätter in 1901. This synthesis started from cycloheptanone and established the seven membered ring structure of the compound.{{cite journal| author = Richard Willstätter| title = Synthesen in der Tropingruppe. I. Synthese des Tropilidens| journal = Justus Liebig's Annalen der Chemie| volume = 317| issue = 2| pages = 204–265| year = 1901| doi= 10.1002/jlac.19013170206| url = https://zenodo.org/record/1427527}}

Cycloheptatriene can be obtained in the laboratory by photochemical reaction of benzene with diazomethane or the pyrolysis of the adduct of cyclohexene and dichlorocarbene.{{cite journal| author = H.E. Winberg| title = Synthesis of Cycloheptatriene| journal = Journal of Organic Chemistry| volume = 24| issue = 2 | pages = 264–265| year = 1959| doi= 10.1021/jo01084a635}} A related classic synthesis for cycloheptatriene derivatives, the Buchner ring enlargement, starts with the reaction of benzene with ethyl diazoacetate to give the corresponding norcaradiene ethyl ester, which then undergoes a thermally-allowed electrocyclic ring expansion to give 1,3,5-cycloheptatriene 7-carboxylic acid ethyl ester.Buchner, et al., Ber., 18, 2377 (1885);For a variation: {{cite journal |author1=Irvin Smith Lee |author2=Tawney Pliny O | year = 1934 | title = Studies on the Polymethylbenzenes. IX. Addition of Ethyl Diazoacetate to Durene | journal = J. Am. Chem. Soc. | volume = 56 | issue = 10| pages = 2167–2169 | doi = 10.1021/ja01325a054 }}

File:TOC_ACS1996v2.svg

File:Chemical_structure_of_heptalene.png|Heptalene – composed of two fused cycloheptatriene rings.

File:Azulene struttura.svg|Azulene – composed of fused cyclopentadiene and cycloheptatriene rings.

File:Pentaheptafulvalene.png|Sesquifulvalene – composed of linked cyclopentadiene and cycloheptatriene rings.

File:Elassovalene.svg|Elassovalene – composed of one cycloheptatriene and two fused cyclopentene rings.

File:Tropone.png|Tropone – composed of cycloheptatriene ring and carbonyl group.

File:Tropolone.png|Tropolone – composed of cycloheptatriene ring, carbonyl and hydroxy groups.

File:Gamma-thujaplicin.png|Hinokitiol – composed of cycloheptatriene ring, isopropyl, carbonyl and hydroxy groups (isopropyl cycloheptatrienolone).