Terpenes molecules

Although the mesoporous materials, such as Ti-MCM-41, have lower intrinsic epoxidation selectivity than TS-1 and Ti-beta, they must nevertheless be used as catalysts for reactions of large molecules typical in the fine chemicals industry. It is, therefore, interesting to elucidate how these ordered mesoporous materials compare with the earlier generation of amorphous titania-silica catalysts. Guidotti et al (189) recently compared Ti-MCM-41 with a series of amorphous titania-silica catalysts for the epoxidation of six terpene molecules of interest in the perfumery industry (Scheme 6). Anhydrous TBHP was used as the oxidant because the catalytic materials are unstable in water. The physical characteristics of these catalysts are compared in Table XII. 

A large quantity of discoloured (and peroxidised) turpentine was heated with fuller s earth to decolourise it, and it subsequently exploded. Fuller s earth causes exothermic catalytic decomposition of peroxides and rearrangement of the terpene molecule. 

Eugenol (4-allyl-2-methoxyphenol) Eugenol is not actually derived from a terpene molecule (as opposed to carvacrol and thymol) but it is a phenol and is found in essential oils of clove, cinnamon leaf, pimento, ylang ylang and rose. It has a spicy, pungent odour typical of clove. 

Monoterpenes of interest in flavourings can be open-chained or cyclic molecules. They can be more or less unsaturated, and they can contain various oxygen functions. Sometimes they may also be bound to non-terpene molecule parts. Among the compounds and their 5-values compiled in Table 6.7, typical representatives will be discussed in detail. Nature-identical isoprenoids are in this context compounds obtained from another natural isoprenoid precursor, because from a commercial point of view, a really synthetic product would not be of interest. 

All the lipid molecules are originally synthesized from the iso-prene units in isopentenyl pyrophosphate molecules. Steroid and terpene molecules are assembled by head-to-tail condensation of these groups. 

Figure 1. The structures of several terpene molecules and the plants from which they are derived.

Monoterpenes A terpene molecule contains 10 carbon atoms (derived from two isoprene units) and at least one double bond. Terpene hydrocarbons are thermally labile and easily oxidized and, thus, citrus oils, which contain a high level of terpenes, do not keep well. Some terpenes are thought to have... 

It turns out that they are chemically related to each other, as you can imagine from the chemical structures shown in Fig. 12.1. They are called terpenes and terpenoids. They can be regarded as derivatives from a five-carbon compound called isoprene (2-methyl butadiene). Two isoprene molecules combine to form mono-terpene (ten-carbon compound). The fragrant oils mentioned above are all the derivatives of mono-terpene. Terpenes are derived from a common metabolic intermediate of glucose, acetyl-CoA (coenzyme A). By the way, a tri-terpene (which three terpene molecules combine to form) called squalene leads to the formation of steroids, and if you connect a large number of isoprene in a linear fashion, you will get natural rubber (Chap. 5). 

Polymers or polymer conjugates can be made from terpene molecules either directly or after certain chemical modifications. Generally, three types of terpene-based polymers can be found in the literature and are classified herein by the... 

Another class of terpene-based polymer bioconjugates includes (co)polymers with pendent terpene moieties. Generally, there are two ways to synthesize these structures (1) graft terpene molecules onto the polymer backbones, and (2) polymerize terpene molecules decorated with polymerizable moieties. This second method is different from the polymerization reactions described in Sect. 2, since... 

Yu G-S, Freedman TB and Nafie LA (1995) Dual circular polarization Raman optical activity of related terpene molecules comparison of backscattering DCP[ and right-angle ICP spectra. Journal of Raman Spectroscopy 26 733-743. 

Paditaxel, a complex terpene molecule with antimitotic activity (commercialized as Taxol ), is used for various cancer treatments, including ovarian and breast cancer treatments. The isolation of this naturally occurring compound requires the harvesting of a large amount of trees and involves difficult purification. A semisynthetic route has been developed based on the coupling of baccatin III (a diterpenoid that can be isolated from yew leaves) with the chiral side-chain (2R,3S)-N-benzoyl-3-phenylisoserine ethyl ester. The latter could be obtained from the diastereoselective microbial reduction of racemic 2-keto-3-(N-benzoylamino)-3-phenylpropionic acid ethyl ester using whole cells of Hansemda sp. (Figure 13.12). Despite concomitant production of the undesired anti diastereomers (2R,3R)-N-benzoyl-3-phenylisoser-ine ethyl ester and (2S,3S)-N-benzoyl-3-phenylisoserine ethyl ester (up to 20%) due to nonperfect selectivity, the C-13 side-chain synthon required for paclitaxel... 

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