Limonene peroxides

It is the chief constituent of the poisonous American wormseed oil and is found in amounts of up to 40% in oE of Cheno podium amhrosioides, although not found in other oils of the same type [52]. Ascaridole, as an inner peroxide, is found on chromatograms at a higher position than the hydroperoxides which have been repeatedly detected as intermediates during epoxide formation. Using n-hexane-diethyl ether (87 + 13), the three limonene peroxides can also be separated under standard conditions (hRf 22, 27 and 33) [85]. 

To 0.165 mole of BMB (prepared as in the preceding experiment) maintained at 0°, is added 20.4 g (0.15 mole) of /-limonene over a period of 5 minutes. The reaction mixture is allowed to stand at room temperature for approximately 3 hours. It is then oxidized by the addition of 50 ml of 3 A sodium hydroxide followed by 50 ml of 30% hydrogen peroxide. The alcohol is worked up in the usual manner. Upon distillation, the primary terpineol is obtained, bp 115-116710 mm. 

Peroxides, hydroperoxides [1, 2] e.g. (photo)-axidation products of limonene [3]... 

Towards the end of this section it may be worthwhile to point out some new reactions with high-valent metals and TBHP. The first is a pyridinium dichromate PDC-TBHP system134. Nonsubstituted or alkyl-substituted conjugated dienes, such as 1,3-cyclooctadiene (87) and others (also linear dienes), yield keto allyl peroxides 88 (equation 18), whereas phenyl-substituted dienes such as 1,4-diphenylbutadiene (89) gave diketo compounds, 90 (equation 19). In further research into a GIF-type system135 with iron and TBHP, limonene gave a mixture of products with carvone as the major product. The mechanism is thought to proceed initially by formation of a Fe(V)-carbon... 

Many EOs also exhibit antioxidant activity and therefore several studies have been carried out in order to elucidate the activity of the components [139,153]. For instance, y-terpinene retarded the peroxidation of linoleic acid [139, 154-156], sabinene showed strong radical-scavenging capacity [139, 157], a-pinene [158] and limonene [146] showed low antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, while terpinene and terpinolene showed high hydrogen-donating capacity against the DPPH radical [146, 150, 155, 158],... 

Kleno, J.G., Wolkoff, P., Clausen, P.A., Wilkins, C.K. and Pedersen, T. (2002) Degradation of the adsorbent Tenax TA by nitrogen oxides, ozone, hydrogen peroxide, OH radical and limonene oxidation products. Environmental Science and Technology, 36, 4121-6. 

Free radical cyclization of 1,6-diene (120) using diethyl phosphite or diphenylpho-sphine oxide initiated by peroxide, produces an organophosphorus compound (121) via the addition of a phosphonyl radical to an olefinic group (eq. 4.42a). Radical addition of PH3 to limonene (122) results in the formation of 4,8-dimethyl-2-phosphabicyclo[3.3.1]-nonane (123) (eq. 4.42b) [121, 122]. 

Bregeault and co-workers have reported supporting [HP04 W0(02)2 2]2 species on resins and silica (Table 4.6).64 Amberlyst A26 was the macro-reticular resin used. The PW2 species was supported onto dehydrated porous silica. The catalysts were found to be highly selective for the epoxidation of limonene by hydrogen peroxide. 

However, in this section, the total synthesis of yingzhaosu A, the lead compound of a particular class of antimalarial 1,2-dioxocins, is reported. The synthesis involves eight steps and a 7.3% overall yield starting from (A)-limonene (Scheme 64). Besides the TOCO procedure that allowed the formation of five bonds in one step, the most intriguing steps involved the selective hydrogenation of a C-C double bond in the presence of a peroxide and an aldehyde functionalities (step vi) and the stereoselective reduction of the side-chain carbonyl with (R)-CBS catalyst (step viii). Last but not least, the old classical fractional recrystallization allowed the separation of yingzhaosu A from its C-14 epimer and saved two synthetic steps <2005JOC3618>. 

Iodine pentafluoride depletes the limonene inhibitor and then causes explosive polymerization of the monomer. Mixtures with hexafluoropropene and air form an explosive peroxide. Reacts violendy with SO3 air difluoromethylene dihypofluorite dioxygen difluoride iodine pentafluoride oxygen. When heated to decomposition it emits highly toxic fumes of F". See also FLUORIDES. 

Tocopherol was effective and ascorbic acid ineffective in the protection of citrus oils evaluated by aroma (13). In a typical study, 5 g of orange oil was oxidized in 75-mL open brown bottles at 45°C and was evaluated by a panel after 6 d, at which time it was ranked as off-odor, "terpeney. The peroxide value of the initial oil was zero the oxidized material had a PV of 100. As a result, days to reach 100 PV was used as an endpoint. Comparative antioxidant effects on a number of citrus oils and on D-limonene [cyclohexene, l-methyl-4-(l-methylethenyl)-(R)-5989-27-5] are presented in Table X. BHA is the most active while AP has no activity alone but does synergize with tocopherol. 

There are some interesting examples of selective ozonolysis in the terpene field. Limonene is ozonized at the 8,9- double bond in preference to the 1- double bond. This is indicated by the fact that the amount of formaldehyde found is almost equal to the amount of ozone introduced, up to 1 mole. In like manner, terpinolene yields acetone in an amount nearly equal to the ozone passed, up to 1 mole. -Pinene should add ozone readily and form formaldehyde and nopinone on ozonolysis. Practically none of these products can be obtained by ordinary ozonolysis techniques. The hydrogens alpha to the double bond, with probable additional activation from the general strain of the system, are so active to peroxidation by oxygen that little ozonide is formed, because of the large excess of oxygen present. 

See the discussion above about International Eragrance Association (IFRA) guidelines that D-limonene is a recommended quencher in that it can decrease the sensitizing effect of cinnamic aldehyde when used at a 1 1 ratio with cinnamic aldehyde. IFRA guidelines also state that limonene and natural products containing substantial amounts of it should only be used when the level of peroxides is kept to the lowest practical level, for instance by adding antioxidants at the time of production. Such... 

Key Words Ethylene oxide, Propylene oxide. Epoxybutene, Market, Isoamylene oxide. Cyclohexene oxide. Styrene oxide, Norbornene oxide. Epichlorohydrin, Epoxy resins, Carbamazepine, Terpenes, Limonene, a-Pinene, Fatty acid epoxides, Allyl epoxides, Sharpless epoxidation. Turnover frequency, Space time yield. Hydrogen peroxide, Polyoxometallates, Phase-transfer reagents, Methyltrioxorhenium (MTO), Fluorinated acetone, Alkylmetaborate esters. Alumina, Iminium salts, Porphyrins, Jacobsen-Katsuki oxidation, Salen, Peroxoacetic acid, P450 BM-3, Escherichia coli, lodosylbenzene, Oxometallacycle, DFT, Lewis acid mechanism, Metalladioxolane, Mimoun complex, Sheldon complex, Michaelis-Menten, Schiff bases. Redox mechanism. Oxygen-rebound mechanism, Spiro structure. 2008 Elsevier B.V. 

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