Catalysts alkylene oxide polyaddition

The mechanism of alkylene oxide polyaddition to hydroxyl groups catalysed by the tertiary amines is much more complex [31]. The most efficient tertiary amines, used as catalysts in the addition of PO to hydroxyl groups, are the low hindered amines, having a minimum of two methyl groups/aminic nitrogen (see Figure 13.2) [30-35]. 

The polyaddition of alkylene oxides to hydroxyl groups is catalysed by the alkali hydroxides (KOH and NaOH) or low hindered tertiary amines or, to a much lesser extent, by acid catalysts [Lewis acids and Bronstedt superacids in order to generate short... 

Bogdal et al. have obtained unsaturated polyesters in polyaddition reactions of alkylene oxides such as epichlorohydrin and acid anhydrides (maleic and phthalic anhydrides) in the presence of lithium chloride as catalyst under microwave irradiation conditions (Scheme 14.22) [51, 52]. In the standard procedure, a mixture of 0.10 mol phthalic anhydride and 0.10 mol maleic anhydride with 0.010 mol ethylene glycol, 0.20 mol epichlorohydrin, lithium chloride (0.1% w/w) was placed in a... 

The preparation methods for the synthesis of unsaturated and saturated polyester resins were also elaborated for micro-wave conditions. In the polyaddition reactions of alkylene oxides (i.e., epichlorohydrin) and acid anhydrides (i.e., maleic and phthalic anhydrides), unsaturated polyesters were prepared in the presence of lithium chloride as a catalyst (Figure 30). In comparison with polycondensation reactions of acid anhydrides with diols, these reactions proceed without the release of by-products. 

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