Polyacetal carboxylic acids

Other Synthetic Polymers - There was very little activity in this particular area during the past year. The most significant finding were the reports 2,43 on polyacetal carboxylic acids. These materials are... 

Similar polyacetals were prepared by BASF scientists from CO-aldehydic aliphatic carboxylic acids (189,190) and by the addition of poly(hydroxycarboxylic acid)s such as tartaric acid to divinyl ethers (191) as biodegradable detergent polymers. 

Similar polyacetal structures were prepared by BASF scientists from general dialdehydes and aliphatic hydroxycarboxylic acids derived from sugars [156, 157], shown in Scheme 15. Alternatively, carboxypolyacetals are available by the addition of polyhydroxy carboxylic acids, tartaric acid, for example, to divinyl ethers [158]. 

Compatibilized blends of hydroxylated polyoxymethylene (polyacetal) with carboxylic acid-functionalized PP have been prepared (Chen et al. 1991). The formadtHi of ester linkages between the polymers was proposed. For example, blends comprising hydroxylated polyoxymethylene and muconic acid-grafted PP were made into film by calendering at 200 °C to provide compositions with markedly improved mechanical properties compared to similar blends containing unfunctionahzed PP or unfunctionalized polyoxymethylene. 

The structures of all Lycopodium alkaloids isolated thus far may be accommodated within the polyacetate biogenetic hypothesis proposed by Conroy 27) which has been alluded to in earlier sections of this review. His scheme proposes that the alkaloids are formed from two 3,5,7-triketooctanoic acid chains. The manner in which the two chains combine is illustrated by the numbering system proposed b " Wiesner (26) and adopted in this review. The odd-numbered C atoms represent the acetate carboxyl and the even-numbered C atoms the acetate methyl groups. This biogenetic scheme was put forward at a time when the structures of only a few alkaloids were known annotinine, lycopodine, a- and j8-obscurine, and selagine. It is perhaps more than coincidental that it also accommodates the novel structural types found in cernuine and serratinine. 

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