Citronellol

Preparation

By reduction of citronellal or geraniol or by fractional distillation of such essential oils as geranium and citronella (Bedoukian, 1967).

Definition

ChEBI: A monoterpenoid that is oct-6-ene substituted by a hydroxy group at position 1 and methyl groups at positions 3 and 7.

Aroma threshold values

Detection at 11 ppb to 2.2 ppm; l-form, 40 ppb

Taste threshold values

Taste characteristics at 20 ppm: floral, rose, sweet and green with fruity citrus nuances.

Synthesis Reference(s)

The Journal of Organic Chemistry, 60, p. 2260, 1995 DOI: 10.1021/jo00112a056Synthesis, p. 391, 1976Tetrahedron Letters, 30, p. 5677, 1989 DOI: 10.1016/S0040-4039(00)76168-5

General Description

Citronellol is a volatile monoterpenic primary alcohol mainly found in the essential oil of plants such as Pelargonium graveolens, Cymbopogon winterianus and Rosa damascena. It is also one of the glycosidically bound aroma compounds in ginger.

Flammability and Explosibility

Nonflammable

Safety Profile

Poison by intravenous route. Moderately toxic by ingestion, skin contact, and intramuscular routes. A severe skin irritant. A combustible liquid. When heated to decomposition it emits acrid smoke and irritating fumes. See also ALCOHOLS.

Synthesis

It is generally accepted to distinguish rhodinol as the product isolated from geranium consisting of a mixture of l-citronellol and geraniol, whereas the name l-citronellol should be used to indicate the corresponding synthetic product with the highest level of purity; dl-citronellol can be prepared by catalytic hydrogenation of geraniol or by oxidation of allo-cyrnene; l-citronellol is prepared from (+) d-pinene via (+) cis-pinene to (+) 2,6-dimethyl-2,7-octadiene and, finally, isolating l-citronellol by hydrolysis of the aluminum-organo compound.

Purification Methods

Purify them bydistillation through a cannon packed (Ni) column and the main cut collected at 84o/14mm and redistilled. Also purify via the benzoate. [IR: Eschenazi J Org Chem 26 3072 1961, Naves Bull Soc Chim Fr 505 1951, Beilstein 1 IV 2188.]