Olefin groups, epoxidation

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). 

In the epoxidation of an olefin with a peracid, the occupied n orbital of the olefin group HOMO) interacts with the vacant orbital (LUMO) of the peracid [143, 144]. The higher-lying aromatic n orbital of the substituted fluorenes (69) can interact with the orbital in a similar manner to spiro conjugation (Fig. 12). 

Electron-deficient olefins, asymmetric epoxidation, 386-91 Electron diffraction dialkyl peroxides, 713 ozonides, 721, 723 1,2,4-trioxolanes, 740 see also Gas electron diffraction Electron-donating substituents ene reactions, 841 sulfonyl peroxides, 1005-7 Electronegative functional groups,... 

Females of the lymantriid, Porthetria dispar, the gypsy moth, liberate cls-7,8-epoxy-2-methyloctadecane (disparlure) as a sex pheromone (78). The probable precursor of the epoxide, (Z)-2-methyl-7-octadecene, is present in the gland in large quantities, and it has been demonstrated that the olefin is epoxidized in vivo (79). Disparlure is rapidly adsorbed on the male antennae and quickly converted to two more polar metabolites (80), probably as a consequence of hydrolysis of the epoxide group. 

Coordination catalysis via alkyl hydroperoxides is well documented (4, 31). Selective oxidations of olefins to epoxides (Reaction 16), using especially Group IV, V, and VI transition-metal complexes, can occur possibly via oxygen-transfer processes of the type... 

Ti(0-/-Pr)4-catalyzed epoxidation works for allyl alcohols with an electron-deficient olefin. The epoxidation of different allyl alcohols bearing an electron-withdrawing group has been attested [596-599] and Eq. (257) compares the stereochemical outcome of a few methods of epoxidation [596]. The titanium-based method generally results in considerable improvement of syn selectivity. The stereoselectivity of the reaction depicted by Eq. (258) is the reverse of that afforded by alkaline peroxide epoxidation [599]. 

Polyesters and polyamides carrying photosensitive cinnamoyl groups have been synthesized. The original polymers contained either epoxide or olefinic groups in the main chain. These were subjected to ring-opening or a combination of hydro-... 

Halohydrins may be used as intermediates in protection of olefins as epoxides and there are some instances of the use of halohydrin acetates to protect double bonds. Overton [49] protected an olefin against both oxidative and reductive conditions by use of the halohydrin acetate and Levine and Wall [50] noted that formation of a halohydrin acetate of the A -olefin in (7) caused the Cj i methyl group to be protected in some way against bromination. Bromhydrin acetates can be... 

Regioselectivity is of particular importance with fundamental starting materials carrying functional groups that offer two reactive positions, such as olefins, acetylenes, epoxides, anhydrides, and imides. There are additionally the two enolate... 

Virtually any reactive type of functionality (or protected function) available as R-Si(OEt)3 or a related trialkoxysilane can be used to close the cage using this synthetic approach. Examples of specific reactive corner groups attached in this way include hydride, chloride, hydroxide, nitriles, amines, isocyanates, styryls, olefins, acryhcs, epoxides, norbomyls, bisphenols, acid chlorides, alcohols, and acids (Fig. 

Functional olefins and epoxides, v/here a functional group is separated from the polymerizable moiety by a spacing arm, have been polymerized via coordinative-anionic and coordination polymerization processes. Metathesis polymerization has recently attracted a considerable amount of interest as well. 

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