Polymerizations of Di Aldehydes

As one might expect, di aldehydes can be polymerized to yield polymers with cyclic ether linkages. This resembles polymerizations of non-conjugated dienes [361]  

Cationic polymerizations can take place by either one of three paths stepwise additions, intermediate-type additions, and concerted additions. When phthalaldehyde is polymerized by cationic mechanism or by y-irradiation at —78°C, the products consist of dioxyphthalan units [362]  

Aromatic aldehydes usually polymerize with difficulty. The enhanced polymerizability of phthalaldehyde is due to formation of intermediates from concerted propagation reactions [362]. 

In the above illustration, the anhydride rings can be either cis or trans in configuration. Cationic polymerizations yield polymers with high cis content. Anionic catalysts and particularly coordination catalysts, like triethylaluminum-transition metal halides, yield high trans polymers [363]. 

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