Epoxidation oxidation

Reaction of olefin oxides (epoxides) to produce poly(oxyalkylene) ether derivatives is the etherification of polyols of greatest commercial importance. Epoxides used include ethylene oxide, propylene oxide, and epichl orohydrin. The products of oxyalkylation have the same number of hydroxyl groups per mole as the starting polyol. Examples include the poly(oxypropylene) ethers of sorbitol (130) and lactitol (131), usually formed in the presence of an alkaline catalyst such as potassium hydroxide. Reaction of epichl orohydrin and isosorbide leads to the bisglycidyl ether (132). A polysubstituted carboxyethyl ether of mannitol has been obtained by the interaction of mannitol with acrylonitrile followed by hydrolysis of the intermediate cyanoethyl ether (133). 

To control the stereochemistry of epoxidation at the 10,11-double bond in intermediates in prostaglandin synthesis, a bulky protective group was used for the C15-OH group. Epoxidation of the tribenzylsilyl ether yielded 88% a-oxide epoxidation of the tri-/ -xylylsilyl ether was less selective. ... 

For the Ti(OiPr)4/silica system, the advantage of MCM-41 (a mesoporous silica) over an amorphous silica is not evident either in terms of activity or selectivity for the epoxidation of cyclohexene with H202 in tert-butyl-alcohol.148 Nevertheless, deactivation of the catalysts seems slower, although the selectivity of the recovered catalysts is also lower (allylic oxidation epoxidation = 1 1). Treatment of these solids with tartaric acid improves the properties of the Ti/silica system, but not of the Ti/MCM-41 system, although NMR,149 EXAFS,150 and IR151 data suggest that the same titanium species are present on both supports. 

Alternative to m-chloroperbenzoic acid.1 This oxidant has been introduced as a suitable replacement for m-chloroperbenzoic acid, which is no longer available from commercial sources because of hazards in the manufacture. Actually MMPP is a safer reagent than MCPBA, which is shock-sensitive and potentially explosive. MMPP is soluble in water and in low-molecular-weight alcohols. The by-product, magnesium phthalate, is water-soluble and easily removed. It is generally more stable than other percarboxylic acids. It can replace MCPBA for the usual classic oxidations epoxidation, Baeyer-Villiger reactions, and oxidation of amines to N-oxides. 

Oxidation/epoxidation methods without the use of chlorinated solvents New greener fluorination methods... 

Dembitsky, M.V., Oxidation, epoxidation and sulfoxidation reactions catalysed by haloperox-idases. Tetrahedron, 2003, 59, 4701. 

Charged polymers Neutral polymers, e.g., polysaccharides, polyvinyl alcohol, polyethylene oxide Epoxide-based, diol, polyethylene glycol. 

J. H. Knox In liquid-phase olefin oxidation, epoxides increase with temperature relative to cleavage products and soon exceed them in yield. In gas phase oxidation at about 300°C. epoxides are minor products... 

Figure 4.5 Metabolism of deuterium-labeled naphthalene via the 1, 2-oxide (epoxide) intermediate, illustrating the NIH shift.

Cvetanovic67 was concerned with oxygen atom reactions with unsaturated hydrocarbons. The oxygen atoms were obtained in his experiments by mercury-photosensitized decomposition of N20. Cvetanovi6 came to the conclusion that the reaction of oxygen atoms with ethylene proceeded essentially with scission of the hydrocarbon bond, while with higher olefins this was not observed. Corresponding oxides (epoxides) and carbonyl compounds were formed in the course of the reaction. 

In the C4 coproduct route isobutane is oxidized with oxygen at 130-160°C and under pressure to tert-BuOOH, which is then used in epoxidation. In the styrene coproduct process ethylbenzene hydroperoxide is produced at 100-130°C and at lower pressure (a few atmospheres) and is then applied in isobutane oxidation. Epoxidations are carried out in high excess of propylene at about 100°C under high pressure (20-70 atm) in the presence of molybdenum naphthenate catalyst. About 95% epoxide selectivity can be achieved at near complete hydroperoxide and 10-15% propylene conversions. Shell developed an alternative, heterogeneous catalytic system (T1O2 on SiOi), which is employed in a styrene coproduct process.913 914... 

Metabolism is the major route of elimination of THC from the body as little is excreted unchanged. In humans, over 20 metabolites have been identified in urine and feces 26 Metabolism in humans involves allylic oxidation, epoxidation, aliphatic oxidation, decarboxylation, and conjugation. The two monohydroxy metabolites (Figure 4.7) 11-hydroxy (OH)-THC and 8-beta-hydroxy THC are active, with the former exhibiting similar activity and disposition to THC, while the latter is less potent. Plasma concentrations of 11-OH-THC are typically <10% of the THC concentration after marijuana smoking. Two additional hydroxy compounds have been identified, namely, 8-alpha-hydroxy-THC and 8,11-dihydroxy-THC, and are believed to be devoid of THC-like activity. Oxidation of 11-OH-THC produces the inactive metabolite, ll-nor-9-carboxy-THC, or THC-COOH. This metabolite may be conjugated with glucuronic acid and is excreted in substantial amounts in the urine. 

The 4a,5a-oxido isomers of Formulas 302 and 303 give the same products (Formulas 304 and 305) (122). Irradiation of mesityl oxide epoxide 306 gives 3-methyl-2,4-pentanedione (Formula 307) in low yield (123). Similar irradiation of isophorone oxide (Formula 308) gives both Formulas 309 and 310 (123). 

The chemoselectivity, regioselectivity, diastereoselectivity, and enantioselectivity of heteroatom oxidations, epoxidations and CH insertions by dioxiranes have been reviewed.26 The selective ring-opening reactions of epoxides at high pressures have been reviewed (in Japanese).27... 

An unusual regiocontrolled oxidation (epoxidation and dihydroxylation) of l-halo-1,3-dienes (equation 13) has been accomplished by use of potassium permanganate-MgSCU, after initial treatment with 2,2-dimethoxypropane78. The preferred epoxy diol is formed with the epoxide being adjacent to the chloro substituent. Further elaboration of these molecules yields highly sought after inositols with controlled stereochemistry. 

The recent development of inorganic crystalline-supported metal catalysts for various liquid-phase oxidation reactions such as alcohol oxidation, epoxidation, Baeyer-Villiger oxidation and oxidation via C—H activation using molecular oxygen (02) or hydrogen peroxide (H202) as an oxidant are reviewed in this chapter. 

Dembitsky VM (2003) Oxidation, Epoxidation and Sulfoxidation Reactions Catalysed by Haloperoxidases. Tetrahedron 59 4701... 

Dioxathiolane oxides, epoxide equivalents and versatile synthons,... 

Scheme 12.13 One-pot oxidation/epoxidation of allylic alcohols. (For experimental details see Chapter 8).

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