Cyclododecatrienes are cyclic trienes with the formula C₁₂H₁₈. Four isomers are known for 1,5,9-cyclododecatriene. The ''trans'',''trans'',''cis''-isomer is a precursor in the production of nylon-12. : CDTisomers

Production

The ''trans'',''trans'',''cis''-isomer is obtained by cyclotrimerization of

butadiene 1,3-Butadiene () is the organic compound with the formula (CH2=CH)2. 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 vin ...

catalyzed by a mixture of

titanium tetrachloride Titanium tetrachloride is the inorganic compound with the formula . It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. is a volatile liquid. Upon contact with humid air, it forms thick clouds ...

and an organoaluminium

co-catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycl ...

. Production capacity in 1995 was 8000 tons. : As aforementioned, titanium catalysts predominantly produce the important ''cis'',''trans'',''trans''- isomer. The all-''trans'' isomer is, however, the product from nickel- and chromium-catalyzed trimerization reactions. The yield of cyclododecatriene through these methods is often greater than 80%. The principal side products are the dimers and

oligomers In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relati ...

of butadiene.

Properties

All of the isomers of 1,5,9-cyclododecatriene are colorless, possess typical

terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ar ...

-like odors, and have low melting points. The all-''trans'' isomer melts at 34 °C while the other three isomers melt below room temperature. All of the isomers behave like typical

olefins In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

. The all-trans and cis,trans,trans isomers in particular tend to form complexes with

transition metals In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that can ...

. They also undergo transannular reactions and

isomerization In chemistry, isomerization or isomerisation is the process in which a molecule, polyatomic ion or molecular fragment is transformed into an isomer with a different chemical structure. Enolization is an example of isomerization, as is tautome ...

Application

Cyclododecatriene is the raw material for the production of dodecanedioic acid (4) through

hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate org ...

to cyclododecane (2) followed by air oxidation in the presence of

boric acid Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolve ...

at elevated temperatures to a mixture of the

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

(3a) and the

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bon ...

(3b). In the final step this mixture oxidized further by

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...

: :

The alcohol (3a) and the ketone (3b) can be purified from the alcohol/ketone mixture under different reaction conditions. Pure cyclododecanol (3a) can be produced from the hydrogenation of the mixture in the presence of a copper-chromium catalyst at 30 MPa and 160 ˚C. Pure cyclododecanone (3b) can be produced through the

dehydrogenation In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. A ...

of the mixture over copper or copper-chromium catalysts on an active support at a temperature range of 230–245 ˚C and atmospheric pressure. Pure cyclododecanone can then be converted into cyclododecanone

oxime In organic chemistry, an oxime is a organic compound belonging to the imines, with the general formula , where R is an organic side-chain and R’ may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substitu ...

, which yields laurolactam after

Beckmann rearrangement The Beckmann rearrangement, named after the German chemist Ernst Otto Beckmann (1853–1923), is a rearrangement of an oxime functional group to substituted amides. The rearrangement has also been successfully performed on haloimines and nitrones ...

. Laurolactam is the precursor to several plastics, such as polyamide 12, which is also known as nylon 12.

2012 Evonik fire

In March 2012, a fire at the Marl Chemical Park operated by

Evonik Industries Evonik Industries AG is a stock-listed German specialty chemicals company headquartered in Essen, North Rhine-Westphalia, Germany. It is the second largest chemicals company in Germany, and one of the largest specialty chemicals companies in the ...

in Marl, Germany, stopped production for an expected duration of several months. The plant produced a substantial proportion of the world's production of CDT, particularly that needed to produce laurolactam, a precursor to the polyamide PA12. This in turn led to concerns for global production of finished goods, particularly in the automotive industry. Other biobased polyamides, not dependent on laurolactam or CDT, have been put forward as alternative materials.

References

{{Reflist Cycloalkenes