Cyclohexa-1,3-diene is an
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
with the formula (C
2H
4)(CH)
4. It is a colorless, flammable liquid. Its refractive index is 1.475 (20 °C, D). A naturally occurring derivative of 1,3-cyclohexadiene is
terpinene
The terpinenes are a group of isomeric hydrocarbons that are classified as monoterpenes. They each have the same molecular formula and carbon framework, but they differ in the position of carbon-carbon double bonds. α-Terpinene has been isolate ...
, a component of
pine oil.
Synthesis
Cyclohexadiene is prepared by the
dehydrobromination
In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications.
Dehydrohalogenation from alkyl halid ...
of 1,2-dibromocyclohexane:
:(CH
2)
4(CHBr)
2 + 2 NaH → (CH
2)
2(CH)
4 + 2 NaBr + 2 H
2
Reactions
Useful reactions of this diene are
cycloaddition
In organic chemistry, a cycloaddition is a chemical reaction in which "two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity" ...
s, such as the
Diels-Alder reaction.
Conversion of cyclohexa-1,3-diene to benzene + hydrogen is exothermic by about 25 kJ/mol in the gas phase.
:cyclohexane → cyclohexa-1,3-diene + 2 H
2 (Δ''H'' = +231.5 kJ/mol; endothermic)
:cyclohexane → benzene + 3 H
2 (Δ''H'' = +205 kJ/mol; endothermic)
:cyclohexa-1,3-diene → benzene + H
2 (Δ''H'' = -26.5 kJ/mol; exothermic)
Compared with its
isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
Is ...
cyclohexa-1,4-diene
1,4-Cyclohexadiene is an organic compound with the formula C6H8. It is a colourless, flammable liquid that is of academic interest as a prototype of a large class of related compounds called terpenoids, an example being γ-terpinene. An isomer ...
, cyclohexa-1,3-diene is about 1.6 kJ/mol more stable.
Cyclohexadiene and its derivatives form
metal-alkene complex
In organometallic chemistry, a transition metal alkene complex is a coordination compound containing one or more alkene ligands. Such compounds are intermediates in many catalytic reactions that convert alkenes to other organic products.Elschenbr ...
es. Illustrative is
C6H8)Fe(CO)3 an orange liquid. This complex reacts with hydride-abstracting reagents to give the cyclohexadienyl derivative
C6H7)Fe(CO)3sup>+. Cyclohexadienes react with
ruthenium trichloride
Ruthenium(III) chloride is the chemical compound with the formula RuCl3. "Ruthenium(III) chloride" more commonly refers to the hydrate RuCl3·''x''H2O. Both the anhydrous and hydrated species are dark brown or black solids. The hydrate, with a va ...
to give
(Benzene)ruthenium dichloride dimer
(Benzene)ruthenium dichloride dimer is the organoruthenium compound with the formula CH)RuCl This red-coloured, diamagnetic solid is a reagent in organometallic chemistry and homogeneous catalysis.
Preparation, structure, and reactions
The dime ...
.
See also
*
1,4-Cyclohexadiene
1,4-Cyclohexadiene is an organic compound with the formula C6H8. It is a colourless, flammable liquid that is of academic interest as a prototype of a large class of related compounds called terpenoids, an example being γ-terpinene. An isomer of ...
*
Cyclohexene
Cyclohexene is a hydrocarbon with the formula C6H10. This cycloalkene is a colorless liquid with a sharp smell. It is an intermediate in various industrial processes. Cyclohexene is not very stable upon long term storage with exposure to light ...
References
{{DEFAULTSORT:Cyclohexadiene, 1,3-
Cyclohexadienes
Conjugated dienes