Cycloheptatriene

Synthesis

Albert Ladenburg first generated cycloheptatriene in 1881 by the decomposition of tropine. 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.

Cycloheptatriene can be obtained in the laboratory by photochemical reaction of benzene with diazomethane or the pyrolysis of the adduct of cyclohexene and dichlorocarbene. 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.

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).

Reactions

Removal of a hydride ion from the methylene bridge gives the planar and aromatic cycloheptatriene cation, also called the tropylium ion. A practical route to this cation employs PCl5 as the oxidant.{{cite journal :[[File:Cycloheptatriene Diels-Alder reaction.svg|550px]] Many metal complexes of cycloheptatriene are known, including Cr(CO)3(C7H8) and cycloheptatrienemolybdenum tricarbonyl.

Cyclooctatetraene and cycloheptatriene are used as a triplet quencher for rhodamine 6G dye lasers.{{cite journal

References

References

1. (2014). "Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book)". [[Royal Society of Chemistry.
2. A. Ladenburg. (1883). "Die Constitution des Atropins". [[Liebigs Annalen.
3. A. Ladenburg. (1881). "Die Zerlegung des Tropines". [[Chemische Berichte.
4. [[Richard Willstätter]]. (1901). "Synthesen in der Tropingruppe. I. Synthese des Tropilidens". [[Liebigs Annalen.
5. H.E. Winberg. (1959). "Synthesis of Cycloheptatriene". [[Journal of Organic Chemistry]].
6. Buchner, et al., Ber., 18, 2377 ('''1885''');
7. (1934). "Studies on the Polymethylbenzenes. IX. Addition of Ethyl Diazoacetate to Durene". [[J. Am. Chem. Soc.]].
8. (1971). "Re-examination of the Cycloaddition of Cycloheptatriene with Maleic Anhydride". Bulletin of the Chemical Society of Japan.
9. James H. Rigby, Kevin R. Fales. (2004). "7α-ACETOXY-(1Hβ, 6Hβ)-BICYCLO[4.4.1]UNDECA-2,4,8-TRIENE VIA CHROMIUM-MEDIATED HIGHER ORDER CYCLOADDITION".
10. (1995). "Cycloheptatriene and -enyl Complexes of the Early Transition Metals". Chemical Reviews.
11. (1970). "Long Pulse Laser Emission From Rhodamine 6G Using Cyclooctatetraene". [[Applied Physics Letters]].