Hydrocarbon sesquiterpene

The investigations of Attaway and co-workers [6, 6 a] are noteworthy in this connection and with regard to the combination of TLC with GC (see p. 114). They were able to achieve a group separation of the CiQ- and Ci5-hydrocarbons on alumina G layers, using perfluorinated alkanes (BP 70—80° C) (Firms 41, 100) as solvent. With a length of run of 7.5 cm, the 19 monoterpenes remained at the start and the 11 sesquiterpene hydrocarbons were separated in the hBf range of 10-71. 

In order to obtain a better separation of monoterpenes and to eliminate the interference of evaporation during chromatography, Adhtkari [1] and Mathis [159] have developed at —15° C, using silica gel G layers and n-hexane (chamber saturation, hBf 25—85). The time of run was shorter and the hBf-values lower than under normal conditions, as Stahl [254] has been able to show (cf. Fig. 49). The mono- and sesquiterpene fractions of Daucus oils have been chromatographed also at —20° C, on silica gel H layers [255]. A separation in accordance with the influence of the C=C double bonds was accomplished with n-hexane-pentane (50 + 50) as solvent. 

Millee and Kiechnee [168] had also suggested activation of the adsorbent layer back in 1953. They achieved this by drying the chromatogram strips over phosphorus pentoxide in a vacuum desiccator at 3 mm mercury pressure. Since the danger of inactivation by air humidity is so great with the standard sizes used today and the standard 250 [i thicknesses, the procedure is of no more than historical interest. 

If mono- and sesquiterpene hydrocarbons are to be distinguished after chromatography, their differing vapour pressures may be used to advantage, according do Demole [42]  

A second TLC plate with silica gel layer is placed on the chromatogram which has been freed from solvent. The layers face each other and are 1 mm apart. By cautious, even heating, the lower boiling monoterpenes are the first to evaporate from the lower chromatogram. They are readsorbed on the upper layer. Reduced pressure is an advantage in that lower temperatures then suffice. Both chromatograms are subsequently sprayed for visualisation. The upper layer should show chiefly the monoterpene hydrocarbon zones the lower, origmal one, the sesquiterpenes. 

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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). 

One consequence of the shift from grassland to shrubland is the potential for significant increases in volatile hydrocarbons added to the atmosphere. The leaves of creosotebush, Larrea tridentata, yielded 0.1 to 0.2 percent of a complex mixture of volatile compounds. That mixture contains several hundred compounds of which 100 accounted for more than 90% of the total volatiles (23). The volatiles that were identified included four monoterpene hydrocarbons, four oxygenated monoterpenes, six sesquiterpene hydrocarbons, eight aromatics like benzyl acetate and ethyl benzoate, plus... 

In a search for allelopathic agents from common weeds, Amaranthus palmerl S. Wats (Palmer amaranth) and Ambrosia artemisiifolia L. (Louisiana annual ragweed) have been analysed for their organic natural products. From A. palmerl phytol, chondrlllasterol, vanillin, 3-methoxy-4-hydroxynitrobenzene and 2,6-dimethoxy- benzoquinone were isolated. From the roots of Ambrosia artemisiifolia four polyacetylenes, a mixture of sesquiterpene hydrocarbons, methyl caffeate, and a mixture of 8-sitosterol and stlgmasterol were obtained. 

Fraction 2 and 3 (P.E.) provided, besides the sesquiterpene hydrocarbon mixture, a compound which on the basis of H NMR and MS spectral evidence was shown to be the acetylenic hydrocarbon pentayneene (9) C,Ht> previously isolated from A. artemisiifolia... 

Resins older than 40 000 years are considered to be fossil resins. The fossilization of resins begins with polymerisation and forms ambers and copals. Most of the ambers are derived from components of diterpenoid resins with a labdanoid structure other ambers are based on polymers of sesquiterpene hydrocarbons such as cadinene, and may include triterpenoids less common ambers from phenolic resins derive from polymers of styrene. Figure 1.4 shows the skeletal structures of the components which make up the polymers occurring in fossil resins [141]. 

D. Joulain and W. A. Konig, The Atlas of Spectral Data of Sesquiterpene Hydrocarbons, E. B. Verlag, Hamburg, 1998. 

The first naturally occurring tricyclo[6.3.0.0 ]undecane to be synthesized was isocomene (757), a colorless oily sesquiterpene hydrocarbon isolated from several plant sources. In 1979, Paquette and Han reported an efficient, stereospecific approach starting with a preformed bicyclic enone, to which the third five-membered ring was appended with proper attention to stereochemistry and position of unsaturation (Scheme LXXX) The pivotal steps are seen to be the stannic chloride-induced cyclization of aldehyde 732 and the conjugate addition of lithium dimethylcuprate to 733 which sets the stereochemistry of the last methyl group. 

In 1979, Bohlmann and Zdero reported the isolation and an unusual sesquiterpene hydrocarbon from Senecio oxyodontus This substance was formulated as 766 on the basis of its spectral characteristics and called senoxydene. However, Galemmo and Paquette have recently prepared this particular compound and determined that it is not identical to the natural product. Their pathway, which is summarized in Scheme LXXXVII, begins by transforming 4,4-dimethylcyclopentenone into bicyclic... 

DC067 Lund, E. D., andj. H. Bruemmer. Sesquiterpene hydrocarbons in processed stored carrot sticks. Food Chem 1992 43(5) 331-335. 

Isolation and identification of five major sesquiterpene hydrocarbons of ginger. Phytochem Anal 1991 2 (1) 26-3 4. 

Nootkatone can be prepared by oxidation of valencene, a sesquiterpene hydrocarbon isolated from orange oils. 

C17H26O, Mr 246.39, is a long-lasting wood fragrance which is prepared by acetylation of cedarwood oil fractions that contain sesquiterpene hydrocarbons, mainly a-cedrene and thujopsene. Acetylation is carried out in the presence of an acidic... 

Major mono- and sesquiterpene hydrocarbons in the oil are (+)-limonene (58-79%) and /3-selinene [17066-67-01], 5-20%. Its typical, long-lasting odor is caused primarily by two lactones, 3-butylphthalide [6066-49-5] and sedanenolide [62006-39-7] (1.5-11%) [328-334]. 

The oils consist primarily of sesquiterpene hydrocarbons their main component is caryophyllene (>50%) [284a, 450a, 450b]. 

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 ... 

It consists almost entirely of sesquiterpene hydrocarbons, and its main component (>60%) is a-gurjunene [489-40-7] [543]. Other qualities of guijun balsam oil containing Calarene [17334-55-3] and o-Copaene [38565-25-5] as main constituents are also found on the market. 

The main component of the oil is (—)-bornyl acetate, but it also contains other bornyl esters (e.g., bornyl isovalerate), terpene and sesquiterpene hydrocarbons, as well as free isovaleric acid, which contributes strongly to the odor of the oil [807-807b]. 

Bisabolene-type sesquiterpenes, e.g. a-bisabolene 74 (Structure 4.20), are widely distributed in nature. This sesquiterpene hydrocarbon is a constituent of bergamot, myrrh and a wide variety of essential oils. Its oxygenated derivatives a-bisabolol [6-methyl-2-(4-methyl-3-cyclohexen-l-yl)-5-hepten-2-ol] 75 and -bisabolol [4-methyl-l-(6-methylhept-5-en-2-yl)cyclohex-3-enol] 76 are found abundantly in chamomile. 

Leaf oil p-pinene (14), sabinene (13), terpinen-4-ol (11), and sesquiterpene hydrocarbons, bicycloger-macrene (29), germacrene D (12)... 

Zingiber officinale Roscoe Sesquiterpene hydrocarbons, zingib-erene (34), p-sesquipheUandrene (12)... 

Gurjun balsam Dipterocarpus spp. Sesquiterpene hydrocarbons, a-gurju-nene (min. 60), calarene, a-copaene... 

Indian curry leaf Murraya koenigii Sesquiterpene hydrocarbons. 

Galbanum Ferula galbaniflua Boiss., F. rubricaulis Boiss. 2-Methoxy-3-isobutyl pyrazine, 5-sec-butyl-3-methyl-2-butenethioate, 1,3,5-undecatriene as minor components, and monoterpene hydrocarbons (75), sesquiterpene hydrocarbons (10), lactones umbeUic acid, umbeUiferone... 

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. 

N.A. Dihydro-P-agarofuran, curcumin, sesquiterpene hydrocarbons, dendrolasin, santalols.8-100 Internally for genitourinary disorder, fever, sunstroke, externally for skin disorder. 

Sesquiterpenic alcohol Sesquiterpene hydrocarbons Sesquiterpene lactones... 

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