PROFILPELAJAR.COM

1,5-Cyclooctadiene
Names
	Preferred IUPAC name Cycloocta-1,5-diene
Identifiers
CAS Number	111-78-4 ; 1552-12-1 (Z,Z) ; 5259-71-2 (Z,E) ; 17612-50-9 (E,E) ;
3D model (JSmol)	Interactive image;
Abbreviations	1,5-COD
Beilstein Reference	2036542; 1209288 (Z,Z)
ChemSpider	7843 ; 74815 (Z,Z) ; 18520443 (Z,E) ; 19971660 (E,E) ;
ECHA InfoCard	100.003.552
EC Number	203-907-1;
MeSH	1,5-cyclooctadiene
PubChem CID	8135; 82916 (Z,Z); 5364364 (Z,E); 5702534 (E,E);
RTECS number	GX9560000; GX9620000 (Z,Z);
UNII	1E1VVD385Z ;
UN number	2520
CompTox Dashboard (EPA)	DTXSID0026888 ;
	InChI InChI=1S/C8H12/c1-2-4-6-8-7-5-3-1/h1-2,7-8H,3-6H2/b2-1-,8-7- Key: VYXHVRARDIDEHS-QGTKBVGQSA-N ; InChI=1/C8H12/c1-2-4-6-8-7-5-3-1/h1-2,7-8H,3-6H2/b2-1-,8-7- Key: VYXHVRARDIDEHS-QGTKBVGQBM;
	SMILES C1CC=CCCC=C1;
Properties
Chemical formula	C8H12
Molar mass	108.184 g·mol−1
Appearance	Colorless liquid
Density	0.882 g/mL
Melting point	−69 °C; −92 °F; 204 K
Boiling point	150 °C; 302 °F; 423 K
Vapor pressure	910 Pa
Refractive index (nD)	1.493
Thermochemistry
Heat capacity (C)	198.9 J K−1 mol−1
Std molar; entropy (S⦵298)	250.0 J K−1 mol−1
Std enthalpy of; formation (ΔfH⦵298)	21–27 kJ mol−1
Std enthalpy of; combustion (ΔcH⦵298)	−4.890 – −4.884 MJ mol−1
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H226, H304, H315, H317, H319, H334
Precautionary statements	P261, P280, P301+P310, P305+P351+P338, P331, P342+P311
Flash point	32 to 38 °C (90 to 100 °F; 305 to 311 K)
Autoignition; temperature	222 °C (432 °F; 495 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

1,5-Cyclooctadiene (also known as cycloocta-1,5-diene) is a cyclic hydrocarbon with the chemical formula C₈H₁₂, specifically [−(CH₂)₂−CH=CH−]₂.

There are three configurational isomers with this structure, that differ by the arrangement of the four C–C single bonds adjacent to the double bonds. Each pair of single bonds can be on the same side (cis,Z) or on opposite sides (trans,E) of the double bond's plane; the three possibilities are denoted cis,cis, trans,trans, and cis,trans; or (Z,Z), (E,E), and (Z,E). (Because of overall symmetry, trans,cis is the same configuration as cis,trans.)

Generally abbreviated COD, the cis,cis isomer of this diene is a useful precursor to other organic compounds and serves as a ligand in organometallic chemistry. It is a colorless liquid with a strong odor. ^[2]^[3] 1,5-Cyclooctadiene can be prepared by dimerization of butadiene in the presence of a nickel catalyst, a coproduct being vinylcyclohexene. Approximately 10,000 tons were produced in 2005.^[4]^[5]

Organic reactions

COD reacts with borane to give 9-borabicyclo[3.3.1]nonane,^[6] commonly known as 9-BBN, a reagent in organic chemistry used in hydroborations:

COD adds SCl₂ (or similar reagents) to give 2,6-dichloro-9-thiabicyclo[3.3.1]nonane:^[7]^[8]

2,6-Dichloro-9-thiabicyclo[3.3.1]nonane, synthesis and reactions

The resulting dichloride can be further modified as the diazide or dicyano derivative in a nucleophilic substitution aided by anchimeric assistance.

COD is used as an intermediate in one of the syntheses of disparlure, a gypsy moth pheromone.^[9]

Metal complexes

1,5-COD binds to low-valent metals via both alkene groups. Metal-COD complexes are attractive because they are sufficiently stable to be isolated, often being more robust than related ethylene complexes. The stability of COD complexes is attributable to the chelate effect. The COD ligands are easily displaced by other ligands, such as phosphines.

Ni(COD)₂ is prepared by reduction of anhydrous nickel acetylacetonate in the presence of the ligand, using triethylaluminium ^[10]

1⁄3[Ni(C₅H₇O₂)₂]₃ + 2COD + 2Al(C₂H₅)₃ → Ni(COD)₂ + 2Al(C₂H₅)₂(C₅H₇O₂) + C₂H₄ + C₂H₆

The related Pt(COD)₂ is prepared by a more circuitous route involving the dilithium cyclooctatetraene:^[11]

Li₂C₈H₈ + PtCl₂(COD) + 3C₇H₁₀ → [Pt(C₇H₁₀)₃] + 2LiCl + C₈H₈ + C₈H₁₂

Pt(C₇H₁₀)₃ + 2COD → Pt(COD)₂ + 3C₇H₁₀

Extensive work has been reported on complexes of COD, much of which has been described in volumes 25, 26, and 28 of Inorganic Syntheses. The platinum complex is a precursor to a 16-electron complex of ethylene:

Pt(COD)₂ + 3C₂H₄ → Pt(C₂H₄)₃ + 2COD

COD complexes are useful as starting materials; one noteworthy example is the reaction:

Ni(COD)₂ + 4CO → Ni(CO)₄ + 2COD

The product Ni(CO)₄ is highly toxic, thus it is advantageous to generate it in the reaction vessel upon demand. Other low-valent metal complexes of COD include cyclooctadiene rhodium chloride dimer, cyclooctadiene iridium chloride dimer, and Fe(COD)(CO)₃, and Crabtree's catalyst.

The M(COD)₂ complexes with nickel, palladium, and platinum have tetrahedral geometry, whereas [M(COD)₂]⁺ complexes of rhodium and iridium are square planar.

(E,E)-COD

The highly strained trans,trans isomer of 1,5-cyclooctadiene is a known compound. (E,E)-COD was first synthesized by George M. Whitesides and Arthur C. Cope in 1969 by photoisomerization of the cis,cis compound.^[12] Another synthesis (double elimination reaction from a cyclooctane ring) was reported by Rolf Huisgen in 1987.^[13] The molecular conformation of (E,E)-COD is twisted rather than chair-like. The compound has been investigated as a click chemistry mediator.^[14]

References

^ "AC1L1QCE - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 14 October 2011.
^ Buehler, C.; Pearson, D. (1970). Survey of Organic Syntheses. New York: Wiley-Interscience.
^ Shriver, D.; Atkins, P. (1999). Inorganic Chemistry. New York: W. H. Freeman and Co. ISBN 978-0-716-72873-3.
^ Schiffer, Thomas; Oenbrink, Georg. "Cyclododecatriene, Cyclooctadiene, and 4-Vinylcyclohexene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_205.pub2. ISBN 978-3527306732.
^ Lee, H; Campbell, M. G.; Sánchez, R. H.; Börgel, J.; Raynaud, J; Parker, S. E.; Ritter, T. (2016). "Mechanistic Insight Into High-Spin Iron(I)-Catalyzed Butadiene Dimerization". Organometallics. 35 (17): 2923–2929. doi:10.1021/acs.organomet.6b00474.
^ Soderquist, John A.; Negron, Alvin (1998). "9-Borabicyclo[3.3.1]nonane Dimer". Organic Syntheses; Collected Volumes, vol. 9, p. 95.
^ Bishop, Roger. "9-Thiabicyclo[3.3.1]nonane-2,6-dione". Organic Syntheses; Collected Volumes, vol. 9, p. 692.
^ Díaz, David; Converso, Antonella; Sharpless, K. Barry; Finn, M. G. (2006). "2,6-Dichloro-9-thiabicyclo[3.3.1]nonane: Multigram Display of Azide and Cyanide Components on a Versatile Scaffold" (PDF). Molecules. 11 (4): 212–218. doi:10.3390/11040212. PMC 6148556. PMID 17962753.
^ Klünenberg, Helmut; Schäfer, Hans J. (1978). "Synthesis of Disparlure by Kolbe Electrolysis". Angewandte Chemie International Edition in English. 17: 47–48. doi:10.1002/anie.197800471.
^ Schunn, R.; Ittel, S. (2007). "Bis(1,5-Cyclooctadiene)Nickel(0)". Inorganic Syntheses. Vol. 28. pp. 94–98. doi:10.1002/9780470132593.ch25. ISBN 978-0-470-13259-3.
^ Crascall, L; Spencer, J. (2007). "Olefin Complexes of Platinum". Inorganic Syntheses. Vol. 28. pp. 126–132. doi:10.1002/9780470132593.ch34. ISBN 978-0-470-13259-3.
^ Whitesides, George M.; Goe, Gerald L.; Cope, Arthur C. (1969). "Irradiation of cis,cis-1,5-cyclooctadiene in the presence of copper(I) chloride". J. Am. Chem. Soc. 91 (10): 2608–2616. doi:10.1021/ja01038a036.
^ Boeckh, Dieter; Huisgen, Rolf; Noeth, Heinrich (1987). "Preparation and conformation of (E,E)-1,5-cyclooctadiene". J. Am. Chem. Soc. 109 (4): 1248–1249. doi:10.1021/ja00238a046.
^ Stöckmann, Henning; Neves, André A.; Day, Henry A.; Stairs, Shaun; Brindle, Kevin M.; Leeper, Finian J. (2011). "(E,E)-1,5-Cyclooctadiene: a small and fast click-chemistry multitalent". Chem. Commun. 47 (25): 7203–5. doi:10.1039/C1CC12161H. PMID 21611648.