Ho leaf oil

The production of natural camphor and camphor oils was formerly several thousand of tons per year, but has declined as a result of the production of synthetic camphor. The same is true for the distillation of linalool-containing camphor oils (Ho oil. Ho leaf oil), which are derived from other varieties of the camphor tree. 

Hotrienol was found for the first time in Ho leaf oil as the S enantiomer [7], but has been found since then in many natural sources for instance, the R enantiomer was found in black tea and in green tea. The product can be used in many flavours, such as eldertlower, grape, berry and honey flavours. It can be prepared from linalool obtained from citrus oils or Chinese Ho oils, but most linalool is obtained by synthesis from isoprene from petrochemical sources. 

Dimethyl-l,5,7-octatrien-3-ol [(15) = R-isomer)] has been found naturally in both chiral forms. The 3S-(+)-enantiomorph occurs in Japanese Ho leaf oil (whence its trivial name, hbtrienol), while the R-isomer has been isolated from black tea and green tea. The R-isomer (15) was synthesised from R-linalyl acetate (10) by bromination with iV-bromosuccinimide, giving three allylically brominated acetates (11), (12), and (13), which all lead to the acetate... 

Linalool (3.17) occurs even more widely than geraniol. The richest source is Ho leaf oil which can contain over 95% linalool. Rosewood contains 80-85% and freesia about 80% linalool. It also occurs at levels around 50% in lavender and in herbs such as coriander and basil. Citrus leaves and flowers also contain significant amounts of linalool. However, it takes its name from the oil of linaloe wood, of which it accounts for about 30%. 

ISO standard 4719 shows character and data for that oil. Adulteration is done by white camphor oil, 1,8-cineole distilled from eucalyptus oil, synthetic camphor, and linalool. Blending is done with ter-penes from eucalyptus oil, turpentine oil, n-bornyl acetate, lavandin, rosemary oil, HO leaf oil, and a terpineol. Detection can be made by GC MS and by multidimensional chiral separation. Ravid (1992) mentions the chiral ratio of terpinen 4 ol as (4S) (+) terpinen-4-ol 93% (4I -(-)-terpinen 4-ol 7%. 

A typical example is the hydroformylation of linalool, a monoterpenoid allyhc alcohol with a pleasant lily odor. It is a key building block for the synthesis of various vitamins and fragrances, such as vitamin A, vitamin E, citral, citronel-lol, and phnol (see Scheme 6.44). Linalool is found in the essential oils of several plants, for example, Brazihan rosewood and Chinese Ho leaf oils, but mostly it is produced industrially from a-pinene or from the petrochemically derived source 6-methylhept-5-en-2-one (Hoflimann-La Roche Process) [144]. 

Linalool (23) is more properly spelt linalool and pronounced with two distinct o sounds, the first long and the second short. This gives an indication of one of its principal sources, Linaloe oil, the essential oil of the Indian tree Bursera delpechiana, which contains levels of 30% linalool and 45-50% of its acetate. However, it is common practice nowadays to omit the diaeresis and even to speU the name with a single letter o. Other synonyms include linalyl alcohol, Licareol (extract from rosewood), and Coriandrol (extract from coriander). It occurs very widely in nature. The richest source is Ho leaf oil from China and Taiwan, which typically contains >90% linalool and levels as high as 97.5%, have been reported (150). Rosewood oil will typically contain 75-85% linalool and it is a major component of many flower (e.g., 80% in Ifeesia and 75% in honeysuckle) and herb (e.g., 65-80% in coriander) oils. Linalyl acetate is also a frequently encountered component of plant oils. Oils in which it plays a particularly important organoleptic role, include lavender ( 50%) and citrus leaf oils (also 50%). 

Camphor (C10H160) Found in essential oils of ho leaf, lavandin, spike lavender, rosemary and sage. An important compound used in many applications including medical preparations, but it is classified as toxic. 

Allylic hydrolysis of geranyl pyrophosphate produces linalool (92). Like geraniol, linalool occurs widely in nature. The richest source is ho leaf, the oil of which can contain well over 90% linalool. Other rich sources include linaloe, rosewood, coriander, freesia, and honeysuckle. Its acetate is also frequently encountered and is a signi cant contributor to the odors of lavender and citrus leaf oils. 

The isomer has been found in cabreuva, niaouli, and neroli oils among others and the (Z)-isomer in neroli, jasmine, ho leaf, and so on. Figure 6.24 shows the structures of farnesol and nerolidol with all of the double bonds in the trans-con guration. 

Namral linalool is extracted mainly from three species. The largest is Brazilian rosewood of which 100-150 tpa is produced. In recent years, there has been some concern about the endangering of the rosewood species by overharvesting and consequently about the sustainability of production of the oil. About 10 tpa is produced from Chinese and Taiwanese Ho leaf. Production from Linaloe oil is only a few tpa in India (151). Minor sources of natural linalool include shin and coriander oils (82). In the past, it was also extracted from lavender and bergamot. 

Efforts are being made to improve the Bay Leaf IndDslry In the West fndies, with a view to a more constant qualily of oil hoing im-... 

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