Limonene
- 5989-27-5 [ (S) - ( ) -limonene ]
- 5989-54-8 [(S) - (-) -limonene ]
- 138-86-3 [ Dipenten unspecified ]
- 7705-14-8 [( ±) -limonene ]
- 6876-12-6 [trans- 1-methyl- 4-( methyl vinyl) cyclohexene ]
Colorless, flammable liquid, characteristic odor of lemons
Liquid
0.84 g · cm 3 ( α - and β - form, 20 ° C)
-95.5 ° C
177.6 ° C
2 hPa (20 ° C)
- Little in water
Attention
20 ml · m-3 and 110 mg · m-3 for D -limonene
4400 mg · kg -1 ( LD50, rat, oral)
Template: Infobox chemical / molecular formula search available
Limonene [ lime ː n] is a natural substance from the group of terpenes ( monocyclic monoterpene ). There are two enantiomers, the (D) - ( ) -limonene ( also referred to as R-( ) -limonene, or shortly ( ) -limonene ) as well as the (S) - (-) -limonene (also known as L- (-) -limonene or short (-) -limonene called ). The racemate of two enantiomers is also called Dipenten.
History
It was first produced in 1878 by Gustave Bouchardat by heating isoprene.
Occurrence
Limonene is the monoterpene occurring in plants most often. (D ) - ( ) -limonene is used mainly in Pomeranzenschalenöl in cumin oil, dill oil in, in coriander oil, in lemon oil (about 65 %) and orange oil ( usually> 90%). It has an orange -like odor. In contrast, (S ) - (- ) -limonene contained in noble fir and in peppermint oil and smells like turpentine. The racemic limonene is among others in the pine oil, in the Siberian pine needle oil, neroli oil, nutmeg oil and camphor before.
Extraction / representation
Limonene is derived primarily from natural material extraction. (D) - ( ) -Limonene is obtained in large quantities as a by- product in the production of orange juice. (S ) - (- ) -limonene is extracted in relatively small amounts of the corresponding oils. The racemic limonene is obtained as a by-product of the acid-catalyzed isomerization of α - and β - pinene.
Properties
Physical Properties
The specific angle of rotation is [ α ] 20 D 126.3 ° [( D) -limonene ] and -126.3 ° [(S) -limonene ].
Chemical Properties
Limonene is light, air, heat, alkali - and acid- sensitive and autoxidized to carvone.
By two successive reactions of oxygen and carbon dioxide is Polylimonencarbonat, a substance with properties similar to polystyrene. It is the starting material for the synthesis of β - selinene, wherein in the first step is reacted with diborane, and then oxidized with hydrogen peroxide.
Use
Traditionally, lime is used as a cheap perfume. Today it is mainly used as a solvent and serves as a cleaner biogenic and diluents, for example, in the paint industry.
The Gram-negative bacterium Pseudomonas putida DSM 12264 can (D ) - ( ) -limonene regioselectively to (D) - to oxidize ( )- perillic, a natural preservative for cosmetics. The biotechnological production of (S) - ( )- perillic from (S) - ( ) -limonene in a laboratory scale was improved in 2010. The developed bioprocess represents a promising option for an industrial application
The (D ) - ( ) -limonene is used as a herbal insecticide.
Even more recently, it serves as a starting material for the synthesis of dronabinol ( synthetic THC). In recent lawsuits lime is also used as a raw material for bioplastics.
Biological Significance
In the metabolism occurs primarily of limonene Perillinsäure, Dihydroperillinsäure, limonene -1 ,2 -diol and Uroterpenol. Limonene is an irritant. Its oxidation products ( D ) - ( -)- carvone and more isomers of limonene, arising out of limonene in the air, are allergenic.
Safety
The flash point of (D ) - ( ) -limonene is 48 ° C, the ignition temperature at 237 ° C. Since (S ) - (- ) -limonene, an enantiomer of (D) - is ( )- limonene, this information also applies to the (S ) - ( -)- limonene. (D ) - ( ) -limonene was not classified as carcinogenic to humans.