Limonene, £ - + - and

In this pyrolysis, sub atmospheric partial pressures are achieved by employing a diluent such as steam. Because of the corrosive nature of the acids (HE and HCl) formed, the reactor design should include a platinum-lined tubular reactor made of nickel to allow atmospheric pressure reactions to be mn in the presence of a diluent. Because the pyrolysate contains numerous by-products that adversely affect polymerization, the TFE must be purified. Refinement of TFE is an extremely complex process, which contributes to the high cost of the monomer. Inhibitors are added to the purified monomer to avoid polymerization during storage terpenes such as t7-limonene and terpene B are effective (10). 

H)- and (+)-1imonenes are widely used ia the manufacture of terpene resias. Additionally, a (-)-limonene and (+)- P-pheUandrene mixture from sulfate turpentine has been used to produce terpene resias. (+)-Limoaeae from the citms iadustry coatiauaHy fiads aew uses as a solveat aot only for its solvency properties but also for its orange oil fragrance. 

Mondello et al. (2, 20-23) have used a multidimensional gas chromatographic system based on the use of mechanical valves which were stable at high temperatures developed in their laboratory for the determination of the enantiomeric distribution of monoterpene hydrocarbons (/3-pinene, sabinene and limonene) and monoterpene alcohols (linalol, terpinen-4-ol and a-terpineol) of citrus oils (lemon, mandarin, lime and bergamot). Linalyl acetate was also studied in bergamot oil. The system consisted of two Shimadzu Model 17 gas chromatographs, a six-port two-position valve and a hot transfer line. The system made it possible to carry out fully... 

They conlalu about 8S per cent, of W-a-pincno, d jior ceui. ol rf-limonene, and 2 per nonl. of an alcohol. Small amounts of carronc, and of a efi-quitcrpeiie, which Is probably cyprcsscue, are also present. 

Linalol is a tertiary alcohol of the formula Cj HjgO, which, with its acetic ester (and traces of other esters) forms the basis of the perfume,of bergamot and lavender oils. By dehydration linalol is converted into terpenes of which the principal are limonene and dipentene, and by esterification into its acetic ester. The examination of the essential oil at different periods of the development of the bergamot fruit has led Charabot and Laloue to the following conclusions. As the fruit matures the essential oil undergoes the following modifications —... 

The quantity of the terpenes increases, without the ratio between the amounts of the two hydrocarbons limonene and dipentene being altered. 

The fact that the amount of total linalol decreases whilst the richness in linalyl acetate increases, proves that linalol appears in the plant at an earlier period than its acetic ester. Further, the free acetic acid acting on the linalol esterifies a portion of it, whilst another portion of this terpene alcohol is dehydrated, with the production of limonene and. dipentene, which are the usual resultants of linalol in presence of certain dehydrating agents. This view is corroborated by the fact that the quantity of the mixed terpenes increases during the esterification, without the slightest variation being observed in the ratio between the... 

Dipentene is the racemic form of the optically active d-limonene and 1-limonene, terpenes which are found to a very large extent in essential oils. Since an equal mixture of d-iimonene and f-limonene is dipentene, it is obvious that whenever optically active limonene is found with a rotation below the maximum, it must contain dipentene. Mixtures of equal quantities of a compound of the optically active limonenes are identical with the corresponding compound prepared from dipentene. It is therefore obvious that the nomenclature is unfortunate and dipentene should be termed i-limonene. 

There seems no room for doubt that the above formula for ortho-limonene is the correct formula for limonene, and the classical synthesis of dipentene by W. H. Perkin, Jun., and his colleagues has proved beyond doubt that it is the correct formula for dipentene or i-limonene. 

These results show that the structure of perillic aldehyde is similar to that of limonene, and that, consequently, the reducible double bond is next to the aldehydic group. 

Degradation of many terpenes has been examined including p-pinene, o-limonene, and trani-caryophyllene (Grosjean et al. 1993c). 

Grosjean D, EL Williams, E Grosjean, JM Andino, JH Seinfeld (1993c) Atmospheric oxidation of biogenic hydrocarbons reaction of ozone with 3-pinene, D-limonene, and rra -caryophyllene. Environ Sci Technol 27 2754-2758. 

CopperQ bromide, Limonene Wilson, C. W. et al., J. Agric. Food Chem., 1975, 23, 636 Addition of all the perester in one portion to limonene and catalytic amounts of copperQ bromide before oxidation had begun, as shown by development of a blue-green colour, led to an explosion. 

The main constituents of spearmint oil are /-carvone (Fig. 13.12.7) and /-limonene (Fig. 13.12.8). Oil of spearmint contains from 45 to 60% l-carvone, 6 to 20% of alcohols, and 4 to 20% of esters and terpenes, mainly /-limonene and cineole (see Fig. 13.12.4)J2J The optically isomeric form of carvone, d-carvone, is found in oil of caraway and oil of dill. Carvone appears to co-occur with limonene when present in a plant. 

Other polymeric binders, natural and synthetic, may be found as paints or varnishes in modern artworks and installations. Artists very easily adopt resins developed as industrial coatings or for specialized applications, and use them according to their creative needs. Natural rubber latex is a water dispersion of 1,4-ds-polyisoprene particles where pigments can be added to give coloured paints. By means of Py-GC/MS the presence of these paints can be easily assessed. As shown in Figure 12.13, the principal marker peaks in the pyrogram are those of isoprene, limonene and other cyclic dimers. 

Wattenberg LW and Coccia JB. 1991. Inhibition of 4-(methylnitrosamino)-l-(3-pyridyl)butanone carcinogenesis in mice by D-limonene and citrus fruit oil. Carcinogenesis 12 115-117. 

Heteropoly acids such as H3PW12O40 (PW) are good catalysts for the hydration of limonene and other monoterpenes. PWs can be used as homogeneous catalysts in solution or supported on, for example, silica or MCM-41 materials. In aqueous acetic acid limonene gives, in the presence of PW, mainly a-terpineol (7) and a-terpinyl acetate (8) [17]. 

Several optically active glycols were prepared from (+ )-limonene and (+ )-a- and (- )-(J-pinene by oxidation with KMn04 (74). An extensive study of the reduction of acetophenone by a complex of LAH and (+ )-l-hydroxycarvomen-thol (51) was made varying solvents and temperature, and the effect of added... 

Representatives of Xantholininae possess an unpaired nonreversible anal gland reservoir at their abdominal tip. As already reported, the secretion contains iridodial, actinidin, terpenoid aldehydes, ketones, limonene, and isopule-gol [8,118]. 

Dehydrogenation of dipentene (d,l-limonene) and 4-vinylcyclohexene has been studied using both the lithium-ethylenediamine catalyst system (4) and the sodium-alumina catalyst system (12). The aromatic compounds p-cymene and ethylbenzene are produced by both types of catalyst however, while vinylcyclohexene yields ethylbenzene rapidly at 0° over a sodium on alumina catalyst, dipentene yields mainly mixed dienes at 0 but at 25 is also rapidly dehydrogenated to p-cymene (12). 

Bouwmeester HJ, Davies JAR, Toxopeus H, Enantiomeric composition of carvone, limonene, and carveols in seeds of dill and annual and biennial caraway YiLnexies, JAgricFood Chem 43 3057-3064, 1995. 

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