Limonene- 1,2-oxide

Further variations on the epoxyketone intermediate theme have been reported. In the first (Scheme 9A) [78], limonene oxide was prepared by Sharpless asymmetric epoxidation of commercial (S)-(-)- perillyl alcohol 65 followed by conversion of the alcohol 66 to the crystalline mesylate, recrystallization to remove stereoisomeric impurities, and reduction with LiAlH4 to give (-)-limonene oxide 59. This was converted to the key epoxyketone 60 by phase transfer catalyzed permanganate oxidation. Control of the trisubstituted alkene stereochemistry was achieved by reaction of the ketone with the anion from (4-methyl-3-pentenyl)diphenylphosphine oxide, yielding the isolable erythro adduct 67, and the trisubstituted E-alkene 52a from spontaneous elimination by the threo adduct. Treatment of the erythro adduct with NaH in DMF resulted... 

Scheme 12 Alternating co-polymerization of PO with CO2 and limonene oxide with CO2 catalyzed by zinc-BDI complex.

Hills, H. G. (1989). Fragrance cycling in Stanhopea pulla (Orchidaceae, Stanhopeinae) and identification of trans-limonene oxide as a major fragrance component. Lindleyana 4 61-67. 

Fig. 4. Shelf-life of encapsulated orange oil samples, as measured by limonene oxide formation at 37°C.

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... 

Storage Stability. The formation of limonene oxide at 37 C was measured as a function of time to determine shelf-life of the encapsulated orange peel oil samples. Figure 6 shows the shelf-life results. A value of 2mg limonene oxide/g limonene was used as the end of shelf-life for oxidized encapsulated oil samples ( 3) The sample dried at 160 C and 105 C inlet and exit air temperatures respectively and the smallest temperature differential (55 C). This sample formed limonene oxide much faster than the other five samples. By 23 days, this powder had reached a value of 2mg limonene oxide/g limonene. The sample dried at 280 C and 105 C inlet and exit temperatures respectively did not reach 2 mg limonene oxide/g limonene until after 34 days of storage at 37 C. This sample also had the largest inlet and exit air temperature differential (175 C). The remaining four samples had reached 2mg limonene oxide/g limonene after about 30 days of storage at 37 C. 

The GC was calibrated using a mixture of known quantities of d-limonene, d-limonene oxide (cis and trans), 2-octanone, and carvone. GC analyses were performed by injecting 1 pi samples with 1 40 split (column flow split flow), into a Hewlett-Packard 5840A GC equipped with a flame ionization detector. A fused silica capillary column 50m x 0.25 mm i.d., coated with OV-101 as a liquid phase was used. Column temperature was programmed from 50-250 C at 10 C/min, and helium was used as the carrier gas. 

The alicyclic epoxide, limonene oxide, which is obtained from a renewable resource has shown modest activity compared to CHO for reaction with C02 to provide a copolymer. This significant decrease in reactivity is presumably due to the steric influence of a disubstitution at one of the ipso carbon centers. Of course, in either highly selective reaction, where complete formation of copolymer or cyclic carbonate occurs, the process displays 100% atom economy. The environmental attractiveness of this process is further enhanced by the fact that reactions are generally carried out in the absence of an organic cosolvent, that is, in C02-swollen epoxide solutions. 

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. 

Figure 1.12 Copolymerization of limonene oxide and C02 in the presence of P-diiminate-zinc acetate complex.

Terpene = p-pinene, carvone, D-limonene, limonene oxide, myrcene... 

In the limonene oxidation reaction, various immobilized systems have been tested as catalyst. The use of MTO supported on poly(vinylpyridine) polymers however turned out to be a poor system for the limonene oxidation since both the conversions and the selectivities were quite a bit lower than the optimal non-immobilized system [56]. These systems were also used in combination with ionic liquids, and here, a similar result as with the non-immobilized system was found, yielding mostly diepoxide, with the best-performing catalyst MTO/PVP-25% in [BMIM][BF4], giving 92% of diepoxide at full conversion [61]. 

Tanabe el al. studied in detail the catalytic action and properties of metal sulfates most of the sulfates showed the maximum acidity and activity by calcination at temperatures below 500°C, with respect to the surface acidity and the acid-catalyzed reaction (118, 119). Other acid-catalyzed reactions were studied with the FeS04 catalyst together with measurement of the surface acidity of the catalyst the substance calcined at 700°C showed the maximum acidity at Ho s 1.5 and proved to be the most active for the polymerization of isobutyl vinyl ether, the isomerization of d-limonene oxide, and the dehydration of 2-propanol (120-122). It is of interest that the catalyst calcined at a slightly higher temperature, 750°C, was completely inactive and zero in acidity in spite of the remarkable activity and acidity when heat treated at 700°C. 

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 oxide Mosla dianthera (miniature OD-R (lemon, floral)... 

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