Monoterpene ethers

The differing flavor effects of hydrolytic reactions in aged wines and heated juices can be understood in terms of the conditions under which different volatile monoterpenes are formed. In aged wines, slow transformations of both free monoterpenes and glycosides give the more thermodynamically stable products which are mainly cyclic compounds of high flavor threshold. Additionally, monoterpene ether formation would be expected (53,54) and this too... 

Rapp, A., Mandery, H., and Ullemeyer, H. (1984). New monoterpenoic alcohols in grape must and wine and their significance for the biogenesis of some cyclic monoterpene ethers, Vitis, 23,84-92. 

The monoterpene ether rose oxide was isolated from Bulgarian rose oil. Since rose oxide has two asymmetric centers, there are four possible... 

At the beginning of the 1960s, Ervin Koviits (1927-2012) found that rose oil consists of at least 275 components (which led to certain disillusionment). These substances, characteristic of rose scent, were still unknown, and might, in an unfavomable case, be present in only trace amounts. The first important component to be discovered was rose oxide [27], a cyclic monoterpene ether, at a concentration of 0.5%. Rose oxide has an unpleasant smell, reminiscent of mineral oU. At high dilution however, it exudes a scent of beautifid freshness and a nuance reminiscent of green leaves. 

Table 2. Properties of Selected Monoterpene Hydrocarbons and Ethers...

For Instance, many terpene derivatives mimic insect hormone actioa Juvabione (15) is the classical example of a juvenile hormone (JH) mimic that prevents egg maturation in Pyrrhocoris bugs. Aromatic terpene ethers (16), methylene dloxyphenyl terpene ethers (17), and other farnesyl derivatives also have JH activity and the latter ones (18) also cause sterility in Pyrrhocoris. For the most part JH active terpenes are among the sesquiterpenes but several monoterpenes also have insect sterilizing effects (19. 20). The acyclic monoterpene cltral reduces the fertility of rats by causing follicular degeneration (21). 

Cineole 42 as well as 1,4-cineole 43 are cyclic ethers (Structure 4.10). All including ascaridol 44 are bicyclic oxygenated monoterpenes. Their formation can be seen in Fig. 4.3. 

Achillea alpina L. A. millefolium L. Shi Cao (Siberian yarrow) (aerial part) Alkaloids, essential oils, achillin, flavonoides, betonicine, achilleine, d-camphor, oxalic acids, ether oils, hydroxycinnamic acids, hydrocyanic acids, hydroxybenzoic acids, anthocyanidines, anthraquinones, phytosterines, carotene, coumarins, monoterpene, sesquiterpene glucosides, desacetylmatricarin.33-222-450 Antibacterial, treat menopause, abdominal pain, acute intestinal disorder, wound infection, snakebite. 

Polygonum bistorta L. Cao He Che (Snakeweed, bistort) (stem, root) Iodine, oxalic acids, coumarins, hydroxycinnamic acids, ether oil, hydroxybenzoic acids, hydrocyanic acids, anthocyanidines, carotenes, anthraquinones, phytosterines, monoterpene, sesquiterpene glucoside, caffeic acid, quercimeritrin, avicularin, gallic acid, protocatechuic acid 50.221.222,223,224 Diuretic, laxative, hemostatic, antifebrile. 

Taraxacum officinale G. H. Weber ex Wigg. Western Pu Gong Ying (Dandelion) (root) Inulin, essential oils, choline, hydroxycinnamic acids, carotenes, ether oils, monoterpene, oxalic acids, hydrocyanic acids, sesquiterpene glucosides, flavonoids, hydroxybenzoic acid, coumarins, anthocyanidines, anthraquinones, phytosterines, squalene, cerylic alcohol, arabinose, vitamins , , C.88-222-450 Sudorific, stomachic, tonic, a remedy for sores, boils, ulcers, abscesses, snakebites. 

By AEDA the four odorants shown in Figure 9 were detected with the highest FD-factors in dill herb [33], A mixture of these compounds, dissolved in water at the same concentration ratios occurring in the herb (Table 16) very much resembled the typical odor of the dill herb. If (S)-a-phellandrene or the dill ether (B and A Fig. 9), respectively, were omitted, the mixture lost its typical odor note. On the contrary, omission of myristicin and methyl 3-methylbutanoate (D and C Fig. 9) did not significantly influence the overall dill herb aroma of the model mixture [33, 66], The data indicated that (S)-a-phellandrene and the dill ether are the character impact compounds of the dill herb. Since, on the basis of AEDA or calculation of OAVs further odorants have been shown to contribute to the dill herb flavor [33, 66], the results of the simulation experiments revealed that obviously the two monoterpenes are able to mask the flavor contributions of these compounds. 

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. 

Nutmeg pericarp oil contained 16 monoterpenes (60%), nine monoterpene alcohols (29%), eight aromatic ethers (7%), three sesquiterpenes (1%), six esters (1%) and eight other minor components. The components were similar to those in nutmeg and mace oils but differed substantially in concentration (Table 9.11). The chief constituents were a-pinene, a-ter-pineol and terpinen-4-ol. The sabinene, myristicin and safrole concentrations were much lower, while the terpinen-4-ol and a-terpineol contents were much higher than in nutmeg and mace oils (Choo et al., 1999). The chief volatiles from nutmeg and mace are indicated in Fig. 9.1. 

Essential oil recovery and composition showed variation with maturity. C. sativum L. fruits grown in Tunisia gave essential oils at the initial, middle and final stages of maturity, with yields of 0.01, 0.12 and 0.35%, respectively. Essential oil at the first stage of maturity consisted mainly of monoterpene alcohols (14.6%), especially linalool (10.96%). Other constituents were monoterpene aldehydes (2.07%), ethers, hydrocarbons and monoterpene ketones, as well as phenols and sesquiterpenes. 

Essential oil at the middle stage of maturity constituted monoterpene alcohols (76.77%), ketones (3.43%), esters (2.85%) and ethers (1.87%). Major constituents at this stage were linalool (76.3%), cis-dihydro carvone (3.21%),geranyl acetate (2.85%) and anethole (1.41%). Essential oils of mature fruit (final stage) were predominated by monoterpene alcohols (88.5%) and ketones... 

Bornane monoterpenes are exemplified by camphene (2,2-dimethyl-3-methylene-bicyclo[2,2,1]heptane), a structure in which two fused cyclopentane rings share three Cs. We can simply represent the camphene skeleton as a cyclohexane with a methylene (—CH2—) cross-link (G6(-CH2—)). The keto derivative camphor (camphor smell), the ether eucalyptol (eucalyptus smell) and the simple bornene a-pinene (pine smell) are familiar examples. 

Whereas the glucose ester 9 has been identified for the first time as a natural wine constituent, glycoconjugates of its reduced form, i.e. of the monoterpene diol 11, are known Riesling wine constituents (2). Under acidic conditions, diol 11 was partially converted into the bicyclic ether 12, the so-called dillether (2). In analogy to the formation of ether 12 from terpene diol 11, a likely formation of lactone 10 from acid 9A could be be expected (cf. Fig. 5). This so-called wine-lactone 10, first identified as an essential oil metabolite in the Koala (55), has recently been established by Guth (34) as a major aroma contributor in two white wine varieties. The 35,3a5,7aR-configured isomer of 10, which has been identified in wine, is reported to possess an unusual low flavor threshold of 0.01-0.04 pg/L of air and a sweet, coconut-like aroma (55). 

Some diverse VOCs (halocarbons, isoprene (CH2C(CH3) CH2CH2), monoterpenes, ethanol, and methyl tert-butyl ether, (CHslsCOCHs)) were found to be photooxidized efficiently on solid aerosols. Solid photocatalyst particles, such as Ti02, ZnO, and Fe20s, were here of special importance, but the VOC oxidation was photoassisted also by dessert sand, volcanic ash, or even by chalk particles (23-25). Similarly, sulfur dioxide was found to... 

PROP Colorless or yellowish, oily, fragrant Uquid. Bp 175-200°, flash p 117°F (CC), d 0.875-0.900 20°/20°. Insol in water sol in chloroform, ether, oils, and in approx 3 vols ale. Found in the trees and bark of Cinnamomum carphora sieh (Fam. iMuraceae) and prepared by fractional distillation of crude camphor oil after the camphor has been crystallized out a white, viscous liquid with cineole as the principal ingredient along with monoterpenes (FCTXAV 11,1011,73),... 

Addition to bicycKc monoterpene olefins. The reagent reacts rcgiospeciiically with y-pinene (I) at —73° in ether to give the unstable 1 I adduct (2 -chlorosulfonyI-2,8,8-irimethyl-3-azatricyplo[5.l.l.0 ]nonane-4-one) in 65% yield. This adduct rearranges either thermally or on contact with silicic acid via a Wagner-Meerwein rearrangement to (3), yield 40 %. The adduct (2) is reduced by sodium sulfite to the /3-lactam (4 2.8,8-trimethyl-3-azatricyclo[5.l.l.O ]nonane-4-one) in 61 % yield. 

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