Limonene oxidation products

Effect of Water Activity. A preliminary study was done to determine the a at which encapsulated orange peel oil was the most stable to oxidation. Figure 1 summarizes the results of this study. The formation of the limonene oxidation product, limonene oxide, was the slowest for the powder adjusted over Mg(NO3)2 (a 0.536). While the levels of oxidation product do not follow in exact order of a, it is evident that better storage stability correlates with a higher a of the powder. This relationship was not anticipated. Literature on lipid oxidation (2, 2) indicates that there is an optimum a for product... 

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. 

Kleno, J. and Wolkoff, P. (2004) Changes in eye blink frequency as a measure of trigeminal stimulation by exposure to limonene oxidation products, isoprene oxidation products and nitrate radicals. International Archives of Occupational and Environmental Health, 77 (4), 235-43. 

The dermal allergenic potential of D-limonene oxidation products has been studied. Air-exposed d-limonene was a strong sensitizer in guinea-pig studies and oxidation of D-limonene is necessary for its sensitizing potential, producing potent allergens such as limonene oxide and carvone. 

Low levels of D-limonene in the diet have not been reported to cause adverse effects in humans. D-Limonene can be a dermal sensitizer (see above for discussion about D-limonene oxidation products) however, an 8% solution of D-limonene in petrolatum did not cause an allergic skin response in any of 25 volunteers tested. D-limonene is also a recommended quencher in that it can decrease the sensitizing effect of cinnamic aldehyde when used at a 1 1 ratio with cinnamic aldehyde (International Fragrance Association, that is, IFRA, guidelines developed and used by the fragrance and consumer product industries). There is inadequate evidence in humans for the carcinogenicity of D-limonene, and the overall conclusion by experts is that, as discussed above, D-limonene produces renal tubular tumors in male rats by a non-DNA reactive a-2-globulin-asso-ciated response. Therefore, the mechanism by which D-limonene increased the incidence of renal tubular tumors in male rats is not relevant to humans. 

R. Marsili, Measuring volatiles and limonene-oxidation products in orange juice by capillary GC, LC GC 4 358. 

C. Samples were withdrawn every two days from the samples stored at 45 C and every three days from the samples stored at 37 C. Pulled samples were stored in screw cap vials at 0 C until analsis by gas chromatography (GC). The products were monitored for the formation of limonene-1,2-epoxide and L-carvone, both oxidation products of d-limonene (3). 

Renewable feedstocks can also be used as the raw materials for the synthesis of green, biodegradable polymers. A pertinent example is polylactate, derived from lactic acid which is produced by fermentation (see earlier). Another recent example is the production of polycarbonates by reaction of C02 with (R)-limonene oxide in the presence of a zinc catalyst (Fig. 8.47) [221]. 

Limonene has recently been used in rice bran oil extraction as an alternative to hexane, which is commonly used in such processes.The yield and quality of crude rice bran oil obtained from the limonene extraction were almost equivalent to those obtained using hexane. Interestingly, although antioxidants were not present in the limonene, only a very small amount (<1 wt%) of oxidation product was found in the recovered limonene, and therefore the solvent is potentially recyclable in such a process. This also suggests that... 

Japanese authors have made comprehensive investigations of the rearrangements of oxiranes in the presence of solid acids, bases, and salts.The model compounds employed were cyclohexene oxide and 1-methylcyclohexene oxide. The effects of the acidic and basic properties of the catalysts on the selectivity were interpreted on the basis of the products obtained. The main products are carbonyl compounds and allyl alcohol isomers. Rearrangements of limonene oxide over acids and bases were studied on five different types of Al203 similar research has been carried out on 2- and 3-carene oxides, cis- and trans-carvomenthene oxides and a-pinene oxide. ... 

Respiratory irritant mixtures can arise from environmental chemical reactions. For example, ozone reacts rapidly with terpenes under environmental ambient conditions to produce aldehydes, ketones, and carboxylic acids. Several studies that have been carried out demonstrated that reaction of ozone with a-pinene, c/-limonene, and isoprene produce low level concentrations (at or below NOEL levels) of oxidation products and that along with residual ozone and terpenes act as respiratory irritants. 1012 Table 17.3 lists the species typically contained in these mixtures along with their K values. As can be seen, the mixtures contain lipophiles (residual terpenes) and hydrophiles (the reaction products). Similar results have also been reported for environmental reaction of terpenes with ozone and nitrogen dioxide. 9 ... 

Rohr AC, Wilkens CK, Clausen PA, et al. Upper airway and pulmonary effects of oxidation products of (+)-alpha-pinene, d-limonene, and isoprene in BALB/c mice. Inhal Toxicol 2002 14(7) 663—84. 

Ketones quantitated in orange oil are carvone, an oxidation product of limonene, found at 0.1% or less, and nootkatone, found at extremely low levels of < 0.01% of peel oil. 

Alternating copolymers of limonene oxide and carbon dioxide have been prepared using -diitninate zinc acetate complexes [92]. These polycarbonate-type copolymers had rather low Mn values (5 500-11 000), but narrow MDWs (close to 1.1). Cataldo and Keheyan [93] studied recently the polymerization of (—)-p-pinene with 4 -radiation, and found that the product was optically active, although such a feature had not been mentioned in earlier studies by other authors [94, 95]. 

Several species of orchids are pollinated by euglossine bees (Dodson et al., 1969 Hills, 1989 Williams and Whitten, 1983). In one example, pollination appears to involve a relatively simple monoterpene. The essential oil complement of Stanhopea pulla, which consisted mostly of -limo-nene oxide (78) (Fig. 19.17), 1,8-cineole (10), and an unidentified monoterpene, varies both quantitatively and qualitatively depending on the time of day. Maximum fragrance production occurs early in the morning. The euglossine bee involved responds to -limonene oxide (78) in mixtures of E- and Z-limonene oxide (Fig. 19.17) (Hills, 1989). 

---