Unsaturated groups epoxidation

Infrared spectra of unsaturated organotin epoxides show absorption bands at 1235 and 850 cm-1, which are typical of epoxy groups, 3085 and 1640 cm-1 (double bonds) and in the range 510-585 cm-1 (Sn—C bonds). Symmetrical deformation vibrations of the CH3 or CH2 group that is closest to the tin atom are related to changes of H—C—H angles and appear in the 1190-1175 cm-1 range 31). 

Compositions having, upon polymerization, good adhesion and sealing properties were described by Nippon Soda [137] in 1986. The composition comprised an epoxidized polybutadiene, epoxy resin, onium salt, and sensitizer. Grace Japan [138] patented the simultaneous photopolymeriza-tion of epoxy compounds and compounds containing unsaturated groups by the use of free radical photoinitiators and sulfonium salts in 1986. 

Uncontrolled oxidation of rubber is detrimental to its physical properties. Oxidation reactions take place readily at unsaturated groups in polymers and are often referred to collectively as epoxidation however, oxidation under controlled conditions can lead to useful products such as the epoxidized natural rubber introduced by the Malaysian Rubber Producers Association (Schults etal., 1983 Cunneen and Porter, 1965 Ceresa, 1965 Avery and Watson, 1956). Natural rubber in the latex form is treated with hydrogen peroxide dissolved in acetic acid. This gives 50% epoxidized natural rubber. This rubber shows very interesting physical properties and excellent carbon black dispersion. Similarly, nonaqueous epoxidizations of synthetic polyisoprene can be achieved... 

Transition Metai-Cataiyzed Epoxidation with Hydrogen Peroxide. There are few transition metal-catalyzed epoxidations of unsaturated fatty acids with hydrogen peroxide. By using a procediue developed by Ishii et al. (26), Bavaj (27) in oiu group epoxidized various fatty acid esters in a two-phase system with a combination of a tungsten heteropoly acid and a phase-transfer catalyst, using 30% H2O2 as the oxidant. (Table 1). 

The photoisomerization of epoxides containing an adjacent unsaturated group has been studied by several groups. The acetone-sensitized isomerization of 3,4-epoxy-oIefins (423) to keto-olefins (424) under 3000 A wavelength... 

Numerous methods of modifying epoxidized polydienes aim at introducing into the structure of these resins some unsaturated groups with increased reactivity. One of these is the reaction of oxiranic groups with unsaturated carboxylic acids (acrylic, methacrylic, itaconic) [222] and, more frequently, with acrylic hydroxy esters, like 2-hydroxyethylmethacrylate, 2-hydroxyethylaciylate, and especially reaction products of the semiester type obtained by the reaction between hydroxyalkylmethacrylates and polycarboxylic acid anhydrides [223,224]. 

So far, in all PHAs, which have been characterized the hydroxyl replaced carbon atom is of R configuration, except in certain special circumstances where there is no chirality. At the identical C-3 or p position an alkyl group that can differ from methyl to tridecyl, is placed. Nevertheless, this alkyl side chain is not essentially saturated unsaturated, aromatic, epoxidized, halogenated and branched monomers have been reported too (Lageveen et al., 1988 Abe et al., 1990 Doi and Abe, 1990 Fritzsche etal., 1990a,b,c Kimetal., 1991,1992 Choi and Yoon, 1994 Hazeretal.,... 

The hydrogenolyaia of cyclopropane rings (C—C bond cleavage) has been described on p, 105. In syntheses of complex molecules reductive cleavage of alcohols, epoxides, and enol ethers of 5-keto esters are the most important examples, and some selectivity rules will be given. Primary alcohols are converted into tosylates much faster than secondary alcohols. The tosylate group is substituted by hydrogen upon treatment with LiAlH (W. Zorbach, 1961). Epoxides are also easily opened by LiAlH. The hydride ion attacks the less hindered carbon atom of the epoxide (H.B. Henhest, 1956). The reduction of sterically hindered enol ethers of 9-keto esters with lithium in ammonia leads to the a,/S-unsaturated ester and subsequently to the saturated ester in reasonable yields (R.M. Coates, 1970). Tributyltin hydride reduces halides to hydrocarbons stereoselectively in a free-radical chain reaction (L.W. Menapace, 1964) and reacts only slowly with C 0 and C—C double bonds (W.T. Brady, 1970 H.G. Kuivila, 1968). 

The reaction of OF2 and various unsaturated fluorocarbons has been examined (35,36) and it is claimed that OF2 can be used to chain-extend fluoropolyenes, convert functional perfluorovinyl groups to acyl fluorides and/or epoxide groups, and act as a monomer for an addition-type copolymerization with diolefins. 

Crystallinity is low the pendent allyl group contributes to the amorphous state of these polymers. Propylene oxide homopolymer itself has not been developed commercially because it cannot be cross-baked by current methods (18). The copolymerization of PO with unsaturated epoxide monomers gives vulcanizable products (19,20). In ECH—PO—AGE, poly(ptopylene oxide- o-epichlorohydrin- o-abyl glycidyl ether) [25213-15-4] (5), and PO—AGE, poly(propylene oxide-i o-abyl glycidyl ether) [25104-27-2] (6), the molar composition of PO ranges from approximately 65 to 90%. 

Group of plastics composed of resins produced by reactions of epoxides or oxiranes with compounds such as amines, phenols, alcohols, carboxylic acids, acid anhydrides and unsaturated compounds. 

The opening of epoxides with neighboring keto groups, accompanied by vinylogous jS-elimination, has already been mentioned (section V). This is an extension of the jS-elimination reactions which occur when a,p- or jS,y-epoxy ketones are opened with acid or base. a,jS-Epoxy ketones give a-substituted a,jS-unsaturated ketones [(162), for example], and j5,y-epoxy ketones give y-substituted a,jS-unsaturated ketones [(163), for example] ... 

In general, epoxidation of steroids with trans-anti-trans ring fusions leads to exclusive formation of the a-oxirane. Steroid Reactions lists examples of exclusive a-epoxide formation from 2-, 4-, 6-, 7-, 8(9)-, 14-, 16- and 17(20)-unsaturated steroids. Further examples of a-epoxidation of steroid 1-enes, 3-enes, 8-enes, 9(ll)-enes, 8(14)-enes and 16-enes have been reported. The preferred attack by the reagent on the a-side of the steroid nucleus can be attributed to shielding of the -side of the molecules by the two angular methyl groups. 

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