Essential oils described

When essential oils are described only by their common names, not only do these exclude the importance of the species but they also do not account for the chemotype e.g. thyme might be Thymus vulgaris CT thymol and rosemary might be Rosmarinus officinalis CT camphor (CT after the name of the essential oil describes the chemotype, naming the significant compound within that oil). 

Martinek [182] has described the reverse procedure for relatively volatile substances (e.g. essential oil components), where the compound to be detected is "distilled onto the reagent plate and reacts with the reagent there. 

The antliorc ireac in detail of ibc morphological and anatomicsl conditions ol the various degenerate species, and in coacinsioa describe the different essential oils, of which the properties arc suiumatiecd in the table below. 

Thujene has not been isolated from any essential oil, and the numerous terpenes described under this name are in all probability non-uniform bodies. 

This sesquiterpene is a monocyclic compound, first isolated from the essential oil of Bisabol myrrh by Tucholka. It was found in oil of limes, and described by Burgess under the name limene. It occurs in several other essential oils. When separated by fractional distillation from lemon oil, Gildemeister and Mullerfound it to have the following characters —... 

Caryophyllene, as isolated from essential oils, and as usually described in literature is, without the slightest doubt, a mixture of at least two, if not three distinct chemical individuals. 

A sesquiterpene has been isolated from the essential oil of Cannabis Indica. This may fairly be considered a definite body, as it has been isolated by many different observers and described by them at different times. Valenta first mentions it. Vignolo describes it as a mobile liquid boiling at 256°, of specific gravity -897 at 15°, and slightly laevo-rotatory. Wood, Spivey, and Easterfield give the boiling-point as 258° to 259°, the specific gravity as -898 at 18°, and the rotation as - 8-6°. 

Linalol, CjoHjgO, is isomeric with geraniol and nerol, but it is structurally isomeric, and not stereoisomeric, as it is known in both optical forms. It was first isolated by Morin from oil of linaloe. The same body has been isolated from various other essential oils, an[Pg.114]

An alcohol of the formula Cj Hj O was isolated from oil of ginger-grass by Schimmel Co., and described by them as dihydrocuminic alcohol. It has, however, now been shown by Semmler and Zaar not to have the constitution assigned to it by Schimmel Co., but to be identical with the alcohol obtained by reducing perillic aldehyde, Cj<,H 40, the aldehyde characteristic of the essential oil of PerUla nankinensis. 

There exists in the essential oil of Maali resin a sesquiterpene alcohol, CigHjgO, corresponding with the sesquiterpene which has already been described. It has the following characters —... 

Terpinyl Acetate.—The acetic acid ester of terpipeol is also a natural ester. It nas a refreshing odour, and is often described as being a bergamot and lavender substitute. The writer, however, considers this description unjustifiable, and that it is really due to the fact that it is so often used and recommended as an adulterant for these two essential oils. Terpinyl acetate isia colourless oil, of the formula... 

This is the solid constituent of the essential oil, melting at 49°. has beei described by Mutschler as primula camphor. 

This body, which is found in the essential oil of Apocynum andosaemi-folium, is isomeric with the last described ketone, being j-methoxy-p-hydroxyphenylmethyl ketone, of the constitution—... 

The determination of alcohols in essential oils depends on the conversion of these compoimds into their acetic esters, and then carrying out an ester determination as described above. 

As part of a study of the secondary chemistry of members of Cistus (the rock-rose) in France, Robles and Garzino (1998) examined the essential oil of C albidus L. Plants were sampled from two areas in Provence characterized by different soil types, calcareous sites west of Marseille, and siliceous sites near Pierrefeu-du-Var and Bormes les Mimosas (PF and BM, respectively, in Fig. 2.23), which lie about 60 km and 80 km to the east, respectively, in the Massif les Maures. Regardless of the soil type, a-zingiberene [88] (Fig. 2.24) was the dominant component. Concentrations of other major components of the plants varied between the two soil types, as summarized in Table 2.6. Many other compounds were present in lesser amounts, but varied little between the two areas. A more recent paper by the same workers (Robles and Garzino, 2000) described an analysis of C. monspeliensis L. leaf oils, the results of which are summarized in Table 2.7. 

Studies of the essential oils of Thymus species have documented the existence of several chemotypes with greater or lesser geographical distinctions among them. In an examination of the essential oils of T. vulgaris L. native to France, Granger and Passet (1973) described six chemical phenotypes based upon the occurrence of a number... 

In addition to the bitter acids and essential oils, the flowers of hops offer a rich array of polyphenolic compounds, primarily chalcones and their accompanying flavanones, many of which are prenylated derivatives (Stevens et al., 1997,1999a, b). The most prominent flavonoid in all plants studied was xanthohumol [342] (3 -prenyl-6 -0-methylchalconaringenin chalconaringenin is 2, 4, 6, 4-tetrahydroxychalcone) (see Fig. 4.11 for structures 342-346). Several additional chalcones—variously adorned with 0-methyl and/or C-prenyl functions—were also encountered, along with their respective flavanones. Three new compounds were described in the Stevens et al. 

The best book describing essential oils and their extraction is The Essential Oils Individual Essential Oils of the Plant Families (in six volumes) by Ernest Guenther, 1948 (reprinted 1972-1998). 

The first fully comprehensive coupling of NP and RP, where the previously described difficulties related to solvents immiscibility were overcome, was developed by Dugo et al. and applied to the analyses of oxygen heterocyclic components of lemon essential oils [22], Based on the configuration described in this work, other applications were developed for the analysis of carotenoids in citrus samples [48], citrus fruit extracts [29], pharmaceutical products [29], and triglycerides in fats and... 

Many cyclic sesquiterpene alcohols are key odor components in essential oils, for example, cedrol in cedarwood oil, the vetiverols in vetiver oil, and the santalols in sandalwood oil. Since these alcohols have not yet been synthesized on an industrial scale, they are described under the oil in which they occur (Chapter 3). Some of their derivatives, however, are discussed in this section. 

Production. Essential oils are obtained from plant materials by distillation with water or steam. After condensation of the vapor phase, the oil separates from the aqueous phase and is removed. The yield of essential oil, based on the starting plant material, generally ranges from a few tenths of 1 % to a few percent. The apparatus used in the production of natural fragrance concentrates is described in [223]. 

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