Monoterpene hydrocarbons from

Isotope Ratio Analysis by HRGC-MS of Monoterpene Hydrocarbons from Citrus Essential Oils... 

Figure 3. Modified Ir values of the monoterpene hydrocarbons from citrus...

The modified Ir data for monoterpene hydrocarbons from the three species of citrus oils were subjected to a multivariate analysis. According to principal component (PC) analysis, the citrus essential oils examined were clearly discriminated, with 93.3% of the accumulation contribution ratio of both PCI and PC2 (Fig. 4A). As shown in Fig. 4B, p-pinene (PCI, 0.530 PC2, -0.80), a-terpinene (0.685 0.062) and P-phellandrene (0.324 0.810) were large for the absolute value of the eigenvector of monoterpene system hydrocarbons, followed by terpinolene (0.367 -0.010). These compounds greatly contributed to the modified Ir discrimination of the citrus essential oils. 

Scheffer, J. J. C., A. Koedam, and A. Baerheim Svendsen. 1976. Occurrence and prevention of isomerization of some monoterpene hydrocarbons from essential oils during liquid-solid chromatography on silica gel. Chromatoeranhia. 9 425-432. 

SvENSSON, L. Monoterpene Hydrocarbons from Jungermannia cordifolia and J. obovata. Phytochem. 13, 651 (1974). 

In the course of our work on carotene biosynthesis we noticed that certain amounts of the radioactively labeled precursor IPP were incorporated into volatile compounds. These compounds turned out to be monoterpene hydrocarbons which also occur in the volatile pattern of daffodil flowers. These findings enabled us to makethe first reporton chromoplasts being the site of monoterpene biosynthesis (Mettal et al. 1988). Another plastid type, i.e. leucoplasts from Citrofortunella mitis fruit exocarps, has been shown to sy.nthesize monoterpene hydrocarbons from IPP (Gleizes et al. 1983). 

CHAYET L., R03AS M.C., CARDEMIL E., 3ABALQU1NTO A.M., VICUNA 3.R. and CORI O. (1977) - Biosynthesis of monoterpene hydrocarbons from [1- H] neryl pyrophosphate and geranyl pyrophosphate by soluble enzymes from CiLiub Umo-num. Arch. Biochem. Biophys., 180 318-327. 

The formation of monoterpene hydrocarbons from geranyl and neryl diphenyl phosphates, J. Chem. Soc. 264 (1969). 

Wood is the raw material of the naval stores iadustry (77). Naval stores, so named because of their importance to the wooden ships of past centuries, consist of rosin (diterpene resin acids), turpentine (monoterpene hydrocarbons), and associated chemicals derived from pine (see Terpenoids). These were obtained by wounding the tree to yield pine gum, but the high labor costs have substantially reduced this production in the United States. Another source of rosin and turpentine is through extraction of old pine stumps, but this is a nonrenewable resource and this iadustry is in decline. The most important source of naval stores is spent sulfate pulpiag Hquors from kraft pulpiag of pine. In 1995, U.S. production of rosin from all sources was estimated at under 300,000 metric tons and of turpentine at 70,000 metric tons. Distillation of tall oil provides, in addition to rosin, nearly 128,000 metric tons of tall oil fatty acids annually (78). 

Figure 10.3 Gas cliromatograms of a cold-pressed lemon oil obtained (a) with an SE-52 column in the stand-by position and (b) with the same column showing the five heart-cuts (c) shows the GC-GC chiral chromatogram of the ti ansfeired components. The asterisks in (b) indicate electric spikes coming from the valve switcliing. The conditions were as follows SE-52 pre-column, 30 m, 0.32 mm i.d., 0.40 - 0.45 p.m film tliickness cairier gas He, 90 KPa (stand-by position) and 170 KPa (cut position) oven temperature, 45 °C (6 min)-240 °C at 2 °C/min diethyl-tert-butyl-/3-cyclodextrin column, 25 m X 0.25 mm i.d., 0.25 p.m film thickness cairier gas He, 110 KPa (stand-by position) and 5 KPa (cut position) oven temperature, 45 °C (6 min), rising to 90 °C (10 min) at 2 °C/min, and then to 230 °C at 2 °C/min. Reprinted from Journal of High Resolution Chromatography, 22, L. Mondello et al, Multidimensional capillary GC-GC for the analysis of real complex samples. Part IV. Enantiomeric distribution of monoterpene hydrocarbons and monoterpene alcohols of lemon oils , pp. 350-356, 1999, with permission from Wiley-VCH.

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... 

Whereas some species oxidize host terpenes more randomly, producing an array of rather unspecific volatiles with little information, others use highly selective enzyme systems for the production of unique olfactory signals. However, apart from transformations of monoterpene hydrocarbons of host trees, oxygenated monoterpenes may well be biosynthesized de novo by the beetles (see below). 

The factors that influence the diastereoselectivity for the class of monocyclic hydrocarbons, from which monoterpenes are the most studied group, are mainly steric and conformational. Monoterpenes, in general, show relatively low overall syn/anti selectivity, usually attributed to the availability of allylic hydrogen atoms in the right alignment for abstraction. 

Other odoriferous materials are derived from the leaves and young twigs of Cistus ladaniferus. Cistus oil is obtained by steam distillation solvent extraction yields cistus concrete. Cistus oil, in contrast to labdanum oil, consists mainly of monoterpene hydrocarbons. 

Various qualities are commercially available. Their compositions may vary considerably because they are prepared from the resins of different Boswellia species. Main constituents of the oil are monoterpene hydrocarbons [284a, 658-661a]. 

Pinaceae needle oils from Pinaceae species contain (—)-bornyl acetate as their main odoriferous component. Other main constituents are monoterpene hydrocarbons such as a- and /3-pinene, limonene, 3-carene, and a- and /3-phellandrene [713-718b]. The oils are used in perfumes for soap, bath products, and air fresheners and in pharmaceutical preparations. 

Cold pressed orange oil contains over 95 by weight monoterpene hydrocarbons. The principal constituent, d-limonene, ranges from 83-97 percent (9), Limonene degradation has been well docu-meted in the literature (LO, 1 1). Anandaraman identified limonene-1,2-epoxide and carvone as two of the earliest degradation products of d-limonene (12, 13). 

For most new aroma chemicals the starting point of synthesis was the hydrocarbons obtained from petroleum refining or the monoterpenes obtained from turpentine. The synthesis of the aldehydes provided the inspiration for such perfumes as Chanel No. 5 and Arpege,... 

The volatile oil of nutmeg constitutes the compounds monoterpene hydrocarbons, 61-88% oxygenated monoterpenes, i.e. monoterpene alcohols, monoterpene esters aromatic ethers sesquiterpenes, aromatic monoterpenes, alkenes, organic acids and miscellaneous compounds. Depending on the type, its flavour can vary from a sweetly spicy to a heavier taste. The oil has a clovelike, spicy, sweet, bitter taste with a terpeny, camphor-like aroma. 

The aroma and flavour of ginger are determined by the composition of its steam-volatile oil, which is comprised mainly of sesquiterpene hydrocarbons, monoterpene hydrocarbons and oxygenated monoter-penes. The monoterpene constituents are believed to be the most important contributors to the aroma of ginger and they tend to be relatively more abundant in the natural oil of the fresh ( green ) rhizome than in the essential oil distilled from dried ginger. Oxygenated sesquiterpenes are relatively minor constituents of the volatile oil but appear to be significant contributors to its flavour properties. 

The celery x parsley hybrid inherited all the terpenoids from celery and heptanol from parsley, while synthesizing new compounds of its own. The content of these new compounds was higher than that of the main celery components, limonene and myrcene (Madjarova et al., 1979). The volatile components of celery consisted of monoterpene hydrocarbons (46.0%) and phthalides (42.3%). The major components were limonene and 3-butyl-4,5-dihydrophthalide (or sedanenolide). Celery volatiles contained higher concentrations of y-lerpinene and a-pinene. A celery-like odour was associated during GC elution with each of the 16 phthalides reported (MacLeod and Ames, 1989). 

Terpenes are the main constituents of the volatile essential oil of M. koenigii leaves, which are used for curry flavouring (MacLeod and Pieris, 1982). The oil of M. koenigii produces less than 4% of other components, with eight monoterpene hydrocarbons (about 16%) and 17 sesquiterpene hydrocarbons (about 80%). The major constituents responsible for aroma are P-caryophyllene, P-gurjunene, P-elemene, P-phellandrene and P-thujene (Kumar et al., 1999). The volatile oils from the leaves of six species of the genus Murraya have been studied by GC-MS and about 60 monoterpene and sesquiterpenes components were identified. From these results, and published... 

Citrus oil dominates this class of essential oil. It is obtained by the cold press method with the exception of lime oil, which is also prepared by steam distillation of essential oil separated during the production of juice.106,107 Aside from bergamot, these oils are primarily monoterpene hydrocarbon mixtures of which (if)-limonene (3) is usually the dominant compound. Since odor contribution of this monoterpene compound is low, it is often removed by distillation or repeated solvent extraction. The resulting oil rich in odor-active compounds is called terpeneless oil and is used extensively. In the case of bergamot and lemon oils, psoralen derivates like bergaptene (64) causing photosensitivity are problematic, and those for fragrance use are rectified to remove it (Table 8). 

Defensive Compounds. Larvae of the weevil Oxyops vitiosa produce a shiny orange secretion that covers their integument and probably acts as deterrent against ants [420]. The composition of the secretion resembles the terpenoid pattern of the host foliage (Melaleuca quinquenervia) from where it is sequestered (concentration about twice that of the host foliage). It contains the sesquiterpene (+)-viridoflorol 230 (Scheme 25), the monoterpene hydrocarbons a-pinene 45, P-pinene 46, limonene 171, a-terpinene 231, and y-terpinene 232 as well as the oxygenated monoterpenesl,8-cineole 58, a-terpineol 233, and terpinen-4-ol 234. 

Mettal, U., Boland, W., Beyer, P. and Kleinig, H. (1988) Biosynthesis of monoterpene hydrocarbons by isolated chromoplasts from daffodil flowers. Eur.. Biochem., 170, 613-6. 

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