Linalool

• (±) -3,7- dimethyl-1 ,6 -octadien- 3-ol
• (RS ) - ( ±) -linalool
• Linalylalkohol
• Licareol [(R) - (-) -linalool ]
• Coriandrol [(S) - ( ) -linalool ]

• 78-70-6 (racemate )
• 126-91-06 [(R) - (-) -linalool ]
• 126-90-9 [(S) - ( ) -linalool ]

Colorless liquid smelling of lily of the valley

Liquid

0.87 g · cm -3 ( 20 ° C)

198-200 ° C. [(S) - ( ) -linalool ]

10 Pa ( 20 ° C)

Poorly in water ( 1.45 g · l-1 at 20 ° C)

Attention

Template: Infobox chemical / molecular formula search available

Linalool is a monovalent, tertiary alcohol from the group of acyclic monoterpenes. Linalool is a colorless liquid with a fresh, flowery smell. The substance has a chiral carbon atom and thus occurs in the form of two enantiomers, the Licareol [(R) - (-) -linalool ] and Coriandrol [(S) - ( ) -linalool ]. It is isomeric with nerol / geraniol as well as to Pinanol, borneol, myrcenol and dihydrocarveol.

Occurrence

Linalool is a component of many essential oils. It occurs in the coriander, hops, nutmeg, ginger, savory, cinnamon, basil, marjoram, thyme, oregano, black pepper, saffron and other herbs.

Also known as esters ( linalyl acetate ) and linalool as it is found in many essential oils. Linalool is also one of the flavors in the wine. With an odor threshold of 0.025 milligrams per liter, it is an important component of the muscatel bouquet.

Production and representation

According to estimates, about 12,000 tons of linalool were industrially produced worldwide in 2000. The natural production exceeds the industry but many times.

For the synthesis methylheptenone is ethynylated. The resulting dehydrolinalool is reduced by partial hydrogenation of linalool. This synthesis was first Leopold Ruzicka and Virgilio Fornasir 1919.

A second possible synthetic route starts from α - pinene. This is hydrogenated to cis- Pinan and air oxidized to cis -or trans - pinane. The hydroperoxide is reductively worked-up to the mixture of cis -or trans- Pinanol, which can be separated by distillation. At temperatures above 500 ° C. cis- Pinanol is then isomerized to Coriandrol and trans Pinanol to Licareol.

Properties

Linalool is a clear, colorless liquid. Coriandrol smells soapy coriander -like, Licareol woody- lavender-like. The smell of the racemate is described as pleasant, slightly refreshing, blumig-holziger/herber odor. Linalool is combustible, the flash point of the liquid is 75 ° C, at the ignition temperature of 235 ° C. The refractive index of the liquid at 20 ° C from 1.46 to 1.4675.

Reactions

Linalool can be hydrogenated with hydrogen over catalysts to tetrahydrolinalool:

Linalool responds as all alcohols with acids to carboxylic acid esters. So linalool can be esterified with acetic acid, for example, to linalyl acetate.

Use

As a component of essential oils as well as pure substance Linalool is used as odor and flavor use.

It is an intermediate in the synthesis of vitamin E.

Hazards

Linalool is irritating to skin and eyes, redness and pain it calls forth. Linalool can be taken orally or by inhalation. It is slightly hazardous for water (WGK 1). The LD50 for rats at oral intake is 2790 mg / kg, dermal absorption at 5610 mg / kg. Linalool has been shown in many tests as not mutagenic. However, it can not be completely ruled out that it is mutagenic. Also, a carcinogenic effect was not detected until today. Chronic intake leads to damage of the liver.

Linalool is one of the Prohaptenen, ie substances whose oxidation products in air ( linalool ) or reaction products on the skin are allergenic. In a European study, 1.3 percent of patients were found to be sensitive to oxidized linalool.