Epoxide-Anhydride Reactions

It was later found that Lewis acids and bases were catalysts for the epoxide-anhydride reaction. The preferred stoichiometry with respect to anhydride and epoxy proved to be 1 1. This relationship led Fischer (3) to propose a mechanism wherein the first step was a reaction between the anhydride and the accelerator to form a carboxyl anion. This anion in turn reacts with an epoxide, and the reaction repeats itself. 

Other substitution reactions have been described with ketones, epoxides, anhydrides, acyl haUdes, amides, and imidates, among others (4). 

In the case of acids and acid anhydrides, reaction can also occur via the hydroxyl groups that are present, including those formed on opening of the epoxide ring. 

To understand and comparev the mechanisms and rates of polyester formation in catalyzed copolymerization, processes taking place in the system epoxide-anhydride without any initiator are described. In this review, copolymerization in the absence of compounds that do not occur in the initial reaction mixture is regarded as a non-catalyzed reaction. This means that the presence of alcohols, phenols or acids is not excluded. These compounds may be considered as copolymerization catalysts however, because of their possible occurrence in the polymerization system they are not regarded as initiators. The presence of OH groups in epoxy compounds, especially in resins where they occur as chlorohydrines (I), monoethers (II), and diethers of glycerol (III)... 

Table 1. Kinetic parameters for non-catalyzed epoxide-anhydride-proton donor reactions"...

Epoxide Anhydride Proton donor Equa- tion Overall reaction order Wi X T rc) Ea kJ/mol Ref. 

It is advisable that the epoxide resin/hardener component has high Tg. A crosslinked IPN was obtained e.g. from epoxynovolak resin, pyromellitic dianhydride, triethanolamine (epoxide — acid anhydride reaction catalyst), BPA/DC and Zn acetate (cyclo-trimerization catalyst) [78],... 

Trifluoroacetyl iodide, generated in situ from trifluoroacetic anhydride and sodium iodide, deoxygenates epoxides.The reaction begins by anti opening of the epoxide, followed by the formation of an... 

Cyanogen bromide, triazine method, cychc trani-2,3-carbonate reaction, carbonylation, periodate oxidation, epoxide activation Curtis azide rearrangement, coupling reagent method, acid anhydride reaction Schiff base formation reaction... 

For Lewis base and Lewis base salt catalyzed anhydride cured epoxy reactions, Fischer (7) proposed that the initial step of an anhydride, epoxide, and tertiary amine system was the activation of the anhydride (reaction 1) ... 

Sorokin, et. al. (9) proposed that the initial step is either solvolysis of the anhydride (reaction 3) or reaction of the tertiary amine with a co-catalyst (water, alcohol, or carboxylic acid) (reaction 4), followed by catalytic reaction of the monoester with the epoxide group (reaction 5). 

Table 5.30. Graft copolymer formation in PEST/Styrene copolymer blends by alcohol + anhydride reaction by acid + epoxide reaction...

An ionic reaction mechanism such as this may be expected to cause charging problems on an electrode surface. This is the case, in fact, as was seen in the ionic conductivity experiments of Part II. An increase in ionic conductivlly was also noted by both Luston and Antoon while studying epoxide-anhydride-tertiary amine reactions. 

Phthalic anhydride, 1, 41, 94, 410, 481 conversion to Ai-carboxyanhydride, 225 epoxide curing reactions, 510 hydrolysis rate, 74... 

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