1,5-Cyclooctadiene (also known as cycloocta-1,5-diene) is a cyclic

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...

with the chemical formula , specifically . There are three

configurational isomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...

s 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 () or on opposite sides () of the double bond's plane; the three possibilities are denoted , , and ; or (), (), and (). (Because of overall symmetry, is the same configuration as .) Generally abbreviated COD, the isomer of this

diene In organic chemistry, a diene ( ); also diolefin, ) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alk''ene'' units, with the standard prefix ''di'' of systematic nome ...

is a useful precursor to other organic compounds and serves as a

ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...

organometallic chemistry Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...

. It is a colorless liquid with a strong odor. 1,5-Cyclooctadiene can be prepared by dimerization of

butadiene 1,3-Butadiene () is the organic compound with the formula CH2=CH-CH=CH2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two ...

in the presence of a nickel catalyst, a coproduct being vinylcyclohexene. Approximately 10,000 tons were produced in 2005.

Organic reactions

COD reacts with borane to give 9-borabicyclo .3.1onane, commonly known as 9-BBN, a

reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

in organic chemistry used in hydroborations: : Synthesis of 9-BBN dimer

COD adds (or similar reagents) to give 2,6-dichloro-9-thiabicyclo .3.1onane: : CODSCl2

The resulting dichloride can be further modified as the di

azide In chemistry, azide (, ) is a linear, polyatomic anion with the formula and structure . It is the conjugate base of hydrazoic acid . Organic azides are organic compounds with the formula , containing the azide functional group. The dominant ...

or di

cyano In chemistry, cyanide () is an inorganic chemical compound that contains a functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. Ionic cyanides contain the cyanide anion . This a ...

derivative in a

nucleophilic substitution In chemistry, a nucleophilic substitution (SN) is a class of chemical reactions in which an electron-rich chemical species (known as a nucleophile) replaces a functional group within another electron-deficient molecule (known as the electrophile) ...

aided by

anchimeric assistance In organic chemistry, neighbouring group participation (NGP, also known as anchimeric assistance) has been defined by the International Union of Pure and Applied Chemistry (IUPAC) as the interaction of a reaction centre with a lone pair of electro ...

. COD is used as an intermediate in one of the syntheses of disparlure, a

gypsy moth ''Lymantria dispar'', also known as the gypsy moth or the spongy moth, is a species of moth in the family Erebidae native to Europe and Asia. ''Lymantria dispar'' is subdivided into several subspecies, with subspecies such as '' L. d. dispar'' ...

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

Metal complexes

File:Ni(cod)2.png,

Bis(cyclooctadiene)nickel(0) Bis(cyclooctadiene)nickel(0) is the organonickel compound with the formula Ni(C8H12)2, also written Ni(cod)2. It is a diamagnetic coordination complex featuring tetrahedral nickel(0) bound to the alkene groups in two 1,5-cyclooctadiene ligands. Thi ...

. File: Crabtree.svg, Crabtree's catalyst. File: Cyclooctadiene-rhodium-chloride-dimer-2D-skeletal.png, The complex . File:Co(C8H12)(C8H13).png, Co(1,5-cyclooctadiene)(cyclooctenyl). File:PdCl2(cod).png,

Dichloro(1,5-cyclooctadiene)palladium Dichloro(1,5-cyclooctadiene)palladium is the organopalladium compound with the formula PdCl2(C8H12) where C8H12 is cycloocta-1,5-diene (cod) or abbreviated PdCl2(cod). It is a yellow solid that is soluble in chloroform. According to X-ray cryst ...

File:Ir2Cl2 cod 2improved.svg, cyclooctadiene iridium chloride dimer File:Cl2Ptcod.png, Dichloro(1,5-cyclooctadiene)platinum 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. is prepared by reduction of

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...

nickel acetylacetonate in the presence of the ligand, using

triethylaluminium Triethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name the compound has the formula Al2( C2H5)6 (abbreviated as Al2Et6 or TEA). This colorless liquid is pyrophoric. It is an industrially important comp ...

: The related is prepared by a more circuitous route involving the dilithium

cyclooctatetraene 1,3,5,7-Cyclooctatetraene (COT) is an unsaturated derivative of cyclooctane, with the formula C8H8. It is also known as nnulene. This polyunsaturated hydrocarbon is a colorless to light yellow flammable liquid at room temperature. Because of ...

: : : Extensive work has been reported on complexes of COD, much of which has been described in volumes 25, 26, and 28 of ''

Inorganic Syntheses ''Inorganic Syntheses'' is a book series which aims to publish "detailed and foolproof" procedures for the synthesis of inorganic compounds.cyclooctadiene rhodium chloride dimer, cyclooctadiene iridium chloride dimer, and , and Crabtree's catalyst. The complexes with nickel, palladium, and platinum have tetrahedral geometry, whereas complexes of rhodium and iridium are

square planar In chemistry, the square planar molecular geometry describes the stereochemistry (spatial arrangement of atoms) that is adopted by certain chemical compounds. As the name suggests, molecules of this geometry have their atoms positioned at the co ...

(''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. Another synthesis (double elimination reaction from a cyclooctane ring) was reported by

Rolf Huisgen Rolf Huisgen (; 13 June 1920 – 26 March 2020) was a German chemist. His importance in synthetic organic chemistry extends to the enormous influence he had in post-war chemistry departments in Germany and Austria, due to a large number of his ...

in 1987. The molecular conformation of (''E'',''E'')-COD is twisted rather than chair-like. The compound has been investigated as a

click chemistry Click chemistry is an approach to chemical synthesis that emphasizes efficiency, simplicity, selectivity, and modularity in chemical processes used to join molecular building blocks. It includes both the development and use of "click reactions", a ...

mediator.

Related compounds

* Dibenzocyclooctatetraene

References

{{DEFAULTSORT:Cyclooctadiene, 1,5- Cycloalkenes Dienes Ligands Eight-membered rings Foul-smelling chemicals