In this issue the chemical identities of molecules with a more or less fresh floral, eau de cologne and bergamot-like odour-character will be discussed. A qualitative odour-structure relationship will be derived from the structures of chemical compounds with a fresh floral odour.
Linalool and acetate
Quantitatively the most important chemical compound with a fresh floral odour-character is linalool, 3,7-dimethyl-1,6-octadien-3-ol, which is a tertiairy monoterpene alcohol. Linalool consist of 2 enantiomers or optical antipods, which are called (R)-(-)-linalool or licareol and (S)-(+)-linalool or coriandrol. Licareol occurs in many flowers, such bitter orange flower and lavender flower and has a fine fresh floral odour-character. Coriandrol occurs in coriander fruits and has a more herbal, floral odour-note. The acetate of (R)-(-)-linalool has even a more freshly floral, slightly fruity, odour and occurs in many plant materials, such as bergamot peel and leaves of bitter orange, which essential oil is called petitgrain oil. Linalool and its acetate are applied in alcoholic and cosmetic perfumery, where it shows a good performance and stability. In functional perfumery, such as heavy duty detergent compounds, however, the stability of linalool and its esters is rather moderate. Linalool and its esters are extremely useful in all types of eau de colognes.
Tetrahydrolinalool and acetate
Tetrahydrolinalool, 3,7-dimethyloctan-3-ol, is used in functional perfumery, because of its stability in more aggressive media. Tetrahydrolinalool and its acetate have also more or less fresh floral olfactive properties, however with a slightly fatty and earthy undertone.
Myrcenol and acetate, Ocimenol and acetate
Myrcenol, 2-methyl-6-methylene-7-octen-2-ol, and its acetate have natural, fresh, floral odours, even more delicate than those of linalool and its acetate.
Ocimenol, 2,6-dimethyl-5,7-octadien-2-ol, and its acetate have very freshly floral olfactive qualities and are preferred to myrcenol and its acetate.
Because of the rather poor stability in chemically active environments myrcenol and ocimenol are preferably used in alcoholic media, such as very fresh natural eau de colognes.
Dihydromyrcenol and acetate
Dihydromyrcenol, 2,6-dimethyl-7-octen-2-ol, is olfactively somewhat reminiscent of linalool.
This chemical compound and its acetate are often used as replacers for linalool and its acetate, because they are stable in aggressive media, where linalool for instance is oxidised, e.g. in detergent compounds with perborate and TAED.
Tetrahydromyrcenol and acetate
Tetrahydromyrcenol, 2,6-dimethyloctan-2-ol and its acetate are sometimes used instead of tetrahydrolinalool and its acetate, because they have a less earthy note and are also stable in all media. The compounds have fresh floral, slightly fatty, odours.
Chemical compounds with a fresh, floral odour-character are found in tertiairy monoterpene alcohols and their lower esters. The compounds are branched chain and have methyl groups on the 2-, 3-, 6- or 7-position. The presence of one or two double bounds increases their freshness and naturalness.
Reprinted by Leffingwell & Associates, 2006, with Permission