Epoxy compounds, reaction with

The idea of the decisive role of complexing reactions makes possible to unterstand such peculiarities of epoxy compound reactions with primary and secondary amines as a rather unusual, from the kinetic point of view, simultaneous occurrence of the autoacceleration and autoinhibition reactions, catalytic and inhibitive effects of various solvents, and obvious ortho-effect of a number of substituents in aromatic amines, the influence of tertiary amines as additives and some other 5,6,13.14.30,... 

Epoxides. Epoxy compounds react with the carboxyl groups of CTPB to form polyesters. The reaction rates and extent of reaction of a number of epoxides have been determined with the model compound hexanoic acid (6). It was found that most epoxides undergo side reactions (as evidenced by the more rapid consumption of epoxide species) but that at least one difunctional epoxide, DER-332 (Dow Chemical Co.) (Table IV), exhibits a clean reaction with carboxylic acids, even in the presence of ammonium perchlorate. 

Thermodynamics of the epoxy compound curing with amines is interesting from two points of view. It concerns all the numerous elementary reactions resulting in the formation of H-complexes in the reaction system and the process as a whole, as well. 

Reactions of model compounds studied bv DSC The development of acid based curing agents, to cure a new generation of UV resistant epoxy resins, required a study of the epoxy/acid reaction with model compounds. A monofunctional, liquid epoxy resin (CARDURA E5) was used as model resin the selected model acids are listed in Table 1.7. 

Ahyl alcohol undergoes reactions typical of saturated, aUphatic alcohols. Ahyl compounds derived from ahyl alcohol and used industriahy, are widely manufactured by these reactions. For example, reactions of ahyl alcohol with acid anhydrides, esters, and acid chlorides yield ahyl esters, such as diahyl phthalates and ahyl methacrylate reaction with chloroformate yields carbonates, such as diethylene glycol bis(ahyl carbonate) addition of ahyl alcohol to epoxy groups yields products used to produce ahyl glycidyl ether (33,34). 

Miscellaneous Reactions. Epoxy compounds yield chlorosubstituted carbonates (45). The reaction of chloroformates with hydrogen peroxide or metal peroxides results in the formation of peroxydicarbonates that are used as free-radical initiators of polymerization of vinyl chloride, ethylene, and other unsaturated monomers (46,47). 

Optically pure (S)-benzyl methyl sulfoxide 139 can be converted to the corresponding a-lithio-derivative, which upon reaction with acetone gave a diastereomeric mixture (15 1) of the /S-hydroxysulfoxide 140. This addition reaction gave preferentially the product in which the configuration of the original carbanion is maintained. By this reaction, an optically active epoxy compound 142 was prepared from the cyclohexanone adduct 141181. Johnson and Schroeck188,189 succeeded in obtaining optically active styrene oxide by recrystallization of the condensation product of (+ )-(S)-n-butyl methyl sulfoxide 143 with benzaldehyde. 

The synthesis of an epothilone model system via an alternative C9-C10 disconnection was first examined by Danishefsky in 1997. However, extension of this C9-C10 strategy to a fully functionalized epothilone intermediate was not successful, demonstrating the limitations of RCM with the early catalysts A and B [116]. In 2002, Sinha and Sun disclosed the stereoselective total syntheses of epoA (238a) and epoB (238b) by the RCM of epoxy compounds 242 in the presence of catalyst C (Scheme 50) [117]. The reaction furnished an inconsequential mixture of isomers 243 (E/Z 1 1) in high yield. Subsequent selective hydrogenation of the newly formed double bond followed by deprotection led to epothilones A and B. 

Another example of interest with regard to the reaction mechanism is the analysis of epoxy groups. Durbetaki60 titrated a-epoxy compounds with HBr (cf., p. 260) in glacial acetic acid with crystal violet as indicator, but the method was slow for glycidyl esters, CH2—CHCH2OOCR. As it concerns a two-step... 

As mentioned earlier, when NO concentration exceeds that of superoxide, nitric oxide mostly exhibits an inhibitory effect on lipid peroxidation, reacting with lipid peroxyl radicals. These reactions are now well studied [42-44]. The simplest suggestion could be the participation of NO in termination reaction with peroxyl radicals. However, it was found that NO reacts with at least two radicals during inhibition of lipid peroxidation [50]. On these grounds it was proposed that LOONO, a product of the NO recombination with peroxyl radical LOO is rapidly decomposed to LO and N02 and the second NO reacts with LO to form nitroso ester of fatty acid (Reaction (7), Figure 25.1). Alkoxyl radical LO may be transformed into a nitro epoxy compound after rearrangement (Reaction (8)). In addition, LOONO may be hydrolyzed to form fatty acid hydroperoxide (Reaction (6)). Various nitrated lipids can also be formed in the reactions of peroxynitrite and other NO metabolites. 

Because visible light is not energetic enough to break chemical bonds, direct production of free radicals by the photoinitiator does not occur. Instead when cationic initiation is needed, as for reaction with epoxies, DIBF is used in conjunction with an iodonium compound such as 4-octyloxyphenyl-phenyliodonium hexaf luoroantimonate (OPPI). It has been proposed that when irradiated, DIBF and OPPI interact to form a cationic species. 

Heterocycles Both non-aromatic unsaturated heterocycles and heteroaromatic compounds are able to play the role of ethene dipolarophiles in reactions with nitrile oxides. 1,3-Dipolar cycloadditions of various unsaturated oxygen heterocycles are well documented. Thus, 2-furonitrile oxide and its 5-substituted derivatives give isoxazoline adducts, for example, 90, with 2,3- and 2,5-dihydro-furan, 2,3-dihydropyran, l,3-dioxep-5-ene, its 2-methyl- and 2-phenyl-substituted derivatives, 5,6-bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]hept-2-ene, and 1,4-epoxy-l,4-dihydronaphthalene. Regio- and endo-exo stereoselectivities have also been determined (259). 

Using different reagents or under various conditions, 2,3-epoxy alcohols can undergo ring-opening reactions with metallic hydrides, giving 1,3-diols or 1,2-diols. As shown in Scheme 4-16, reduction of 3-substituted 2,3-epoxy alcohols with Red-Al leads to the exclusive formation of 1,3-diols, and this can be applied in the preparation of 1,3-diol compounds.31... 

We have chosen epoxy olefin 10 as substrate for our initial examinations for two reasons. Firstly, 10 is synthesized in a straightforward manner from al-lyl diethyl malonate by epoxidation and an Sn2 reaction with prenyl bromide. Secondly, it is known from the work of others [17-20] and ourselves [65, 66,73,74] that compounds similar to 10 cyclize to yield mainly the essential ds-fused radicals with selectivities of about 85 15 to 90 10. 

Matsuda, H., Dohi, H. and Ueda, M. (1987). Catalysts for the etherification reaction of wood with an epoxy compound. Mokuzai Gakkaishi, 33(11), 884—891. 

Sn2 Reactions with epoxides and aziridines are also synthetically useful. An example of epoxide cleavage with an organocopper reagent with sp carbon moieties is the enantioselective synthesis of (3S, 4S)-4-methyl-3-heptanol (53), an elm bark beetle (Scolytus multistriatus) pheromone [42]. The chiral epoxy oxazolidine 51 [43], prepared from (R)-phenylglycinol, reacted with a propylmagnesium bromide-derived cuprate at —70 °C to afford the oxazolidine 52 in 74% yield (Scheme 9.12). Compound 52 was converted into the target molecular 53 by conventional procedures. 

Bisphenol A, a compound highly used in the production of epoxy resins and polycarbonate plastics, forms monochloro-, dichloro, trichloro-, and tetrachloro derivatives when chlorinated [127], Its reaction with ozone produces as major transformation products, catechol, orthoquinone, muconic acid derivatives of bisphenol A, benzoquinone, and 2-(4-hydroxyphenyl)-propan-2-ol [128],... 

Each substrate was oxidized to the corresponding carbonyl compounds in good yields. Moreover, the coexisting olefin linkage remained intact upon treatment with the oxodiperoxochromium complex and no epoxy compounds were observed in the reaction mixture. Hexavalent chromium reagents such as anhydrous chromium trioxide and pyridinium... 

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