Epoxides additions

Detailed investigations indicated an interesting mechanism for azide openings catalyzed by 2 [6]. Chloride-epoxide addition products were observed in the initial stages of the ARO reaction with 2 in amounts commensurate with the catalyst loading. Azide complex 3, characterized as the TH F adduct, was isolated from the reaction mixture and proved to be an active and recyclable catalyst for the ARO, pointing to the role of 2 as that of a precatalyst. Kinetic experiments revealed a second-order dependence on the concentration of 3, a zero-order dependence on azide source, and inverse-order dependence on epoxide concentration. The sue-... 

As a general rule, the addition of ethylene oxide to a resin backbone will tend to increase the water solubility of the compound. The addition of propylene oxide or butylene oxide to the resin will tend to increase the hydrocarbon solubility of the compound. Often, the dehazer or demulsifier can be made to perform selectively in oil-water systems by adding both ethylene oxide and propylene oxide to the same molecule. Performance and solubility of the alkoxylated compound can then be finely tuned by closely controlling the amount and order of epoxide addition. A random EO-PO based fuel demulsifier is shown in FIGURE 6-6. 

Deoxygenation of epoxides. Di-, tri-, and tetrasubstituted epoxides are converted into alkcncs by treatment with PI3 (or P2h). The reaction occurs most readily with a,/J-disubstiluted epoxides and with >98% retention of configuration. With more substituted epoxides addition of pyridine or triethylamine improves yields by preventing formation of alkyl iodides. 

These reactions are catalysed by acids such as Lewis acids, phenols, and alcohols. The hydroxyl groups formed by the amine epoxide addition are active catalysts, so that the curing reaction usually shows an accelerating rate in its early stages, typical of auto catalysis. In some cases when the amine is present in less than stoichiometric concentrations, reaction of epoxide and hydroxyl may occur to produce an ether group ... 

A study of the reaction of PGE and aniline using high purity reagents and excluding traces of hydroxylie materials, has been reported by Enikolopiyan 56). This demonstrated that amine-epoxide addition can occur in the absence of acidic catalysts, and the observed overall rate was second-order in amine concentration. 

A kinetic model which includes both amine-epoxide and hydroxyl-epoxide addition reactions, with hydroxyl autocatalysis has been proposed by Zukas 103,104). The starting point was an expression for the rate of consumption of epoxide by reaction with primary or secondary amine and hydroxyl groups... 

Olefin Epoxides Addition products and their fractions Carbonyl compounds ... 

Liquefaction of untreated wood can also be achieved at a lower temperature of 150°C and at atmospheric pressure in the presence of a catalyst [12]. Phenolsulfonic acid, sulfuric acid, hydrochloric acid, and phosphoric acid were used as catalysts. In this acid catalyst method, phenols and polyhydric alcohols can also be used for the coexisting organic solvents. Phenol, cresol, bisphenol A and F, and so forth are successfully adoptable as the phenols. Polyethylene glycols, polyether polyols (epoxide additionally reacted polyether polyol, polyethylene terephthalate polyol) have been found to liquify wood resulting in polyol solutions [13]. Liquefaction of wood in the presence of -caprolactone, glycerin, and sulfuric acid has also been accomplished. It was confirmed in this case that liquefaction and polymerization, the latter of which produces polycaprolactone, take place in the reaction system at the same time [14]. Besides the wood material, it has become apparent that trunk and coconut parts of palm, barks, bagasse, coffee bean wastes, and used OA papers can also be liquified [15]. 

To draw each product of epoxidation, add an O atom from either side of the alkene, and keep all substituents in their original orientations. The cis methyl groups in c/s-2-butene become cis substituents in the epoxide. Addition of an O atom from either side of the trigonal planar alkene leads to the same compound—an achiral meso compound that contains two stereogenic centers. 

Cleavage of epoxides with hydrogen sulfide has been exploited advantageously by Perveev and co-workers < - in the eyn-thesis of certain substituted thiophenes from acetylenic epoxides. Addition of hydrogen sulfide occurs, as anticipated, by attack on the epoxide carbon atom furthest from the triple bond. The resulting... 

After workup with ammonium chloride (liberation of NH3 and NaCl) and extraction with hot dimethylsulfoxide products 4 and 5 can be isolated as white solids in yields of ca. 30 %. The low yield of the desired product observed for the epoxide addition reaction is attributed to an anionic epoxide polymerisation process [5],... 

Catalytic asymmetric epoxidation, Addition of heat-activated, powdered 3-5 A molecular sieves to the asymmetric epoxidation of allylic alcohols increases the rate and, more importantly, permits use of catalytic amounts of titanium reagent and the tartrate ester. However, it is still important to use at least a 10% excess of the tartrate ester over Ti(0-i-Pr)4 a 20% excess is usually advisable. In general, 5% of Ti(0-/-Pr)4 and 7.5% of the tartrate ester is used for the catalytic epoxidation. 

Selective reduction to 128 was achieved in much improved yield (56%). The A ring modification to 129 was then accomplished by Eschenmoser cleavage of the derived epoxide, addition of methyllithium, and trifluoracetic acid mediated cyclization to 130. 

Haralabakopoulos and co-workers [173] carried out a study of PET chain extension using various bis-epoxides. Additives studied were ... 

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