Occurrence
Reported found in the essential oils of bergamot, lavender, clary sage and lavandin; also identified among
the constituents of the essential oils of Salvia officinalis, petitgrain, sassafras, neroli, lemon, Italian lime, jasmine, Mentha citrata,
Mentha aquatica, Thymus mastichina, etc; also reported in abundant quantities in the essential oil from flowers, leaves and stems
of Tagetes patula, in the distillate from leaves of Citrus aurantifolia from India, and in the essential oil of Mentha arvensis. Also
reported found in citrus peel oils and juices, berries, peach, celery, tomato, cinnamon, clove, nutmeg, pepper, thymus, grape wines,
avocado, mushroom, marjoram, mango, cardamom, coriander, gin, origanum, lovage, laurel, myrtle leaf, rosemary, sage and mastic
gum oil.
Definition
ChEBI: 3,7-dimethylocta-1,6-dien-3-yl acetate is a monoterpenoid that is the acetate ester of linalool. It forms a principal component of the essential oils from bergamot and lavender. It is an acetate ester and a monoterpenoid. It is functionally related to a linalool.
Preparation
Linalyl acetate is synthesized by two methods:
1) Esterification of linalool requires special reaction conditions since it tends to
undergo dehydration and cyclization as it is an unsaturated tertiary alcohol.
These reactions can be avoided as follows: esterification with ketene in the
presence of an acidic esterification catalyst below 30 °C results in the formation
of linalyl acetate without any by-products. Esterification can be achieved in good yield, with boiling acetic anhydride, whereby the acetic
acid is distilled off as it is formed; a large excess of acetic anhydride must
be maintained by continuous addition of anhydride to the still vessel.
Highly pure linalyl acetate can be obtained by transesterification of tert-butyl
acetate with linalool in the presence of sodium methylate and by continuous
removal of the tert-butanol formed in the process.
2) Dehydrolinalool, obtained by ethynylation of 6-methyl-5-hepten-2-one, can
be converted into dehydrolinalyl acetatewith acetic anhydride in the presence
of an acidic esterification catalyst. Partial hydrogenation of the triple bond
to linalyl acetate can be carried out with, for example, palladium catalysts
deactivated with lead.
Taste threshold values
Taste characteristics at 5 ppm: floral, green, waxy, terpy, citrus, herbal and spicy nuances.
Synthesis
Normally prepared by direct acetylation of linalool; another method starts from myrcene hydrochloride, anhydrous
sodium acetate and acetate anhydride in the presence of a catalyst; all synthetic methods tend to avoid the simultaneous formation
(because of isomerization) of terpenyl and geranyl acetate.
