Sesquiterpenes, alcohols hydrocarbon

Guaiol and Bulnesol. The main constituents of guaicwood oil are the sesquiterpene alcohols guaiol [489-86-1] (107) and bulnesol (108). When the alcohols are dehydrated with acid, many of the hydrocarbons formed are also found ia patchouli oil. 

Schimmel Co. attempted to acetylise the alcohol by means of acetic anhydride, but the reaction product only showed 5 per cent, of ester, which was not submitted to further examination. The bulk of the alcohol had been converted into a hydrocarbon, with loss of water. Ninety per cent, formic acid is most suitable for splitting off water. Gne hundred grams of the sesquiterpene alcohol were heated to boiling-point with three times the quantity of formic acid, well shaken, and, after cooling, mixed with water. The layer of oil removed from the liquid was freed fi-om resinous impurities by steam-distillation, and then fractionated at atmo.spheric pressure. It was then found to consist of a mixture of dextro-rotatory and laevo-rotatory hydrocarbons. By repeated fractional distillation, partly in vacuo, partly at ordinary pressure, it was possible to separate two isomeric sesquiterpenes, which, after treatment with aqueous alkali, and distillation over metallic sodium, showed the following physical constants —... 

Capnellane is the generic name applied to a group of sesquiterpene alcohols and the hydrocarbon isolated from the soft coral Capnella imbricata A < >-Capnellene (667), the presumed biosynthetic precursor of the capnellenols, was first synthesized in 1981 by Stevens and Paquette Their synthetic plan called for the construction of bicyclic ketone 668 and its appropriate annulation. The latter event was achieved by application of the Rupe rearrangement to 668, conjugate addition of a vinyl group to 669, ozonolysis, and cyclization (Scheme LXVIII). Hydrogenation and olefination completed the sequence. 

In addition to 75% monoterpene hydrocarbons (Oa-pinene 5-21% /7-pinene 40-70% 3-carene 2-16%) and ca. 10% sesquiterpene hydrocarbons, galbanum oil contains a fairly large number of terpene and sesquiterpene alcohols and their acetates. Minor components, with entirely different structures and low odor threshold values, contribute strongly to the characteristic odor [284a, 515-519]. Examples are as follows ... 

Monoterpene hydrocarbons, limonene (40-72), a-pheUandrene (10-24) and sesquiterpene alcohol elemol (1-25)... 

Sesquiterpenic alcohol Sesquiterpene hydrocarbons Sesquiterpene lactones... 

Figures 1 and 2 show the capillary gas chromatographic analyses of the hydrocarbon and the oxygenated hydrocarbon fractions. In the hydrocarbon fraction, 13 selected monoterpene compounds and sesquiterpene compounds were compared. In the oxygenated hydrocarbon fraction, 22 volatile components, which include aliphatic aldehydes, 2-alkanones, citral, monoterpene alcohols and sesquiterpene alcohols, were compared.

The mass spectra of a large number of sesquiterpenoids have been published. These consist mainly of hydrocarbons together with a limited number of alcohols and aldehydes. The mass spectra of some furanosesquiterpenoids have also been published. G.l.c. data have been collected for a number of sesquiterpene alcohols and furanosesquiterpenoids. ... 

The volatile constituents of Conyza dioscorides L. (Desf.) growing in Egypt showed promising antimicrobial activities against some tested microorganisms [153]. The volatile constituents consisted mainly of sesquiterpene hydrocarbons and oxygenated sesquiterpenes. The major sesquiterpene hydrocarbons are (3-maaliene and a-elemene, while the major oxygenated sesquiterpene compounds are a-cadinol, muurolol, caryophyllene oxide isomers and a sesquiterpene alcohol. 

Rao et al. isolated ishwarone (391) as one of the chief constituents of the roots of A. indica [347], Subsequent investigations by Ganguly et al. and Govindachari et al. led to the first structural assignment of ishwarone (391) as a novel tetracyclic sesquiterpene ketone based on eremophilane skeleton, the first of its kind to occur in the nature [348,349]. Ishwarane (388), reported from the roots of A. indica by Govindachari et al. is the first tetracyclic sesquiterpene hydrocarbon based on the eremophilane skeleton [334], A tetracyclic sesquiterpene alcohol, ishwarol (389) is also reported from the roots of A. indica [350]. Pakrashi et al. isolated (125)-... 

A number of monoterpene and sesquiterpene hydrocarbons with resin-like odors have been identified, including limonene, a-terpinene, /t-cimene and myrcene, as well as sesquiterpene alcohols such as farnesol. The organoleptic role of these compounds in wine has not been clearly established (Schreier et al, 1976 Bayonove, 1993). 

Different organic groups have been used in synthetic perfumes hydrocarbons, terpenes, sesquiterpenes, alcohols (dtronelol, geraniol, cinnamic alcohol), fenols (p-cresol, thymol), aldehydes (cuminaldehyde, vanillin), ketones (carvone, muscone, ionones, metilion-ones), lactones (nonalactone, undecalactone), esters (acetates, formates, butyrates), nitrogen compounds (indol, methyl anthranilate, musk xylol, quinoHnes). 

Perfumes are composed of hundreds of aromatic chemicals, namely, fragrance chemicals, or just simply fragrances. Among these compounds, it is very common to find compounds with the characteristic five-carbon isoprene unit, giving them the names of terpenes, such as terpene aldehydes, monoterpene alcohols, sesquiterpene alcohols, terpene ketones, terpene esters, monoterpene hydrocarbons, or sesquiterpene hydrocarbons. In addition, other compounds, such as aldehydes, alcohols, ketones, esters, phenols, or lactones, are also very common. 

Waxes in general can contain a wide range of different compounds, including aliphatic diols, free alcohols, hydrocarbons (especially squalene), aldehydes, ketones, hydroxy-ketones, p-diketones and sesquiterpenes. The composition and biochemistry of waxes in nature, and methods for their analysis, have been reviewed in a comprehensive monograph [491],... 

P-Caryophyllene is a common component of many essential oils. For example, the essential oil of black pepper (see Table 8.32, later) contains about 20% of P-caryophyllene. Its a-isomer humulene (also known as a-caryophyllene) occurs in the hops essential oil Humulus lupulus, Cannabaceae) both compounds are often present in the mixture. Common components of essential oils are also bisabolenes. Higher quantities of P-bisabolene (10-15%) and also a-zingiberene (22-30%), ar-curcumene (20%), a-selinene and p-farnesene are found in ginger essential oil. The essential oil of white sandalwood Santalum album, Santalaceae) contains, in addition to sesquiterpenic alcohols as major components, many sesquiterpenic hydrocarbons, including a-bergamotene or-curcumene, P-bisabolene and many others. Trivial and systematic names of the main sesquiterpenic hydrocarbons are listed in Table 8.3. 

Ch. II., The Constituents of Essential Oils and Synthetic Perfume Bodies. — Hydrocarbons—Sesquiterpenes —Alcohols—Terpene Alcohols—Esters— Aldehydes—Ketones— Phenols and Phenolic Compounds—Oxides and Lactones— Nitrogen Compounds — Sulphur Compound—Free Acids. 

Among the complex mixtures that comprise a perfume, the fragrance chemicals they contain can be classified in different families according to their chemical structure, where it is usual to find the five-carbon isoprene unit in most of them, giving them the names of terpenes. So, one can find monoterpene hydrocarbons (e.g. Umonene), sesquiterpene hydrocarbons (e.g. a-famesene), alcohols (e.g. ai-3-hexenol), monoterpene alcohols (e.g. linalool), sesquiterpene alcohols (e.g. famesol), phenols (e.g. eugenol), aldehydes (e.g. 2,6-nonadienal), terpene aldehydes (e.g. citral), ketones (e.g. cyclohexanone), terpene ketones (e.g. jS-ionone), lactones (e.g. y-undecalactone), esters (e.g. methyl salicylate), terpene esters (e.g. linalyl acetate), and oxides (e.g. eucalyptol), etc. Some examples are depicted in Figure 6.1.1. 

Terpenes are characterized as being made up of units of isoprene in a head-to-tail orientation. This isoprene concept, invented to aid in the stmcture deterrnination of terpenes found in natural products, was especially useful for elucidation of stmctures of more complex sesquiterpenes, diterpenes, and polyterpenes. The hydrocarbon, myrcene, and the terpene alcohol, a-terpineol, can be considered as being made up of two isoprene units in such a head-to-tail orientation (1). 

The majority of the turpentine comes from the southeastern United States, which consists of 60—70% a-pinene, 20—25% P-pinene, and 6—12% other components. Because there is variation in components from different species of the pine tree as well as variation from the many paper pulp mills, there is obviously variation in the analysis of sulfate turpentines. Some of the other components consist of -menthadienes, alcohols, ethers such as anethole [104-46-1] and methylchavicol [104-67-0] and the sesquiterpene hydrocarbon, P-caryophyUene [87-44-5]. 

Important commercial sesquiterpenes mosdy come from essential oils, for example, cedrene and cedrol from cedarwood oil. Many sesquiterpene hydrocarbons and alcohols are important in perfumery as well as being raw materials for synthesis of new fragrance materials. There are probably over 3000 sesquiterpenes that have been isolated and identified in nature. 

Gedrene and Gedrol. Cedarwood oil is one of the essential oils whose production is large and provides a source for synthesizing a number of derivatives. Gedrene (91) and thujopsene (92) are the two main sesquiterpene hydrocarbons found in the oil, along with a number of minor components (187). Gedrol [77-53-2] (93) is the main alcohol component of the oil. 

Patchouli alcohol. Patchouli oil comes from Pogostemonpatchouli and the main constituent is patchouli alcohol [5986-55-0] (105) or patchoulol. Another component of the essential oil is norpatchoulenol (106), a norsesquiterpene derivative as a minor (3—5%) constituent, important ia determining the overall odor of the essential oil (197). The price of patchouli oil ia 1995 was 20.90/kg from Indonesia (69). Alarge proportion of the oil (40—60%) is comprised of sesquiterpene hydrocarbons that do not have much odor value. World production of the oil was at about 750 t ia 1984. It is valuable ia perfumery bases because of its characteristic woody, herbaceous odor (198). 

It is convenient to here mention the hydrocarbon verbenene, C,gH,4, on account of its relationship with pinene. It results from the action of acetic anhydride on verbenol, thei alcohol corresponding with the ketone, verbenone. So produced it is laevo-rotatory. The dextro-rotatory and racemic varieties are also known. The sesquiterpenes have the following characters when regenerated from their respective dibromides —... 

When caryophyllene alcohol is dehydrated by means of zinc chloride or phosphorus pentoxide, a hydrocarbon results, which does not appear to be identical with any of the sesquiterpenes described under the name caryophyllene. It has therefore been named clovene . Clovene has the following characters —... 

Ultrasound-assisted extraction is a rapid technique that can also be used with mixtures of immiscible solvents hexane with methanol-water (9 1), for example, is a system used for the Brazilian plant Lychnophora ericoides (Asteraceae). The hexane phase concentrated less polar sesquiterpene lactones and hydrocarbons, while the aqueous alcohol phase concentrated flavonoids and more polar sesquiterpene lactones. 

Essential oils may comprise volatile compounds of terpenoid or non-terpe-noid origin. All of them are hydrocarbons and their oxygenated derivatives. Some may also contain nitrogen or sulphur derivatives. They may exist in the form of alcohols, acids, esters, epoxides, aldehydes, ketones, amines, sulphides, etc. Monoterpenes, sesquiterpenes and even diterpenes constitute the composition of many essential oils. In addition, phenylpropanoids, fatty acids and their esters, or their decomposition products are also encountered as volatiles [1-16, 21-33, 36-38]. 

A wide variety of EOs are known to possess antimicrobial properties and in many cases this activity is due to the presence of active constituents, mainly attributable to isoprenes such as monoterpenes, sesquiterpenes and related alcohols, other hydrocarbons and phenols [8, 9]. 

Volatiles of three cultivars of mango (Jaffna, Willard, and Parrot) from Sri Lanka were analysed, and among the 76 components identified, monoterpenes and sesquiterpenes hydrocarbons were described as the major contributors [42]. Variations in the amounts of esters, ketones, and alcohols were also related. 

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