Polyenes, macromolecular

Chemical Reactions of Model Polyenes and Macromolecular Polyenes... 

Chemical Modification. Reactions on the macromolecular polyenes were carried out by procedures described previously (3, 4). PhHgCBr3 is obtained by a modification of Seyferth s method (21) from PhHgBr and HCBr3 in presence of a base. Yields similar to those reported in the literature are obtained more easily by replacing the complex (tert-BuOK— tert-BuOH) with a solution of sodium tert-amylate in benzene as prepared by Conia (24). This reagent was, in fact, used systematically in place of potassium tertf-butylate it is easier to use and can be prepared completely free of alcohol. 

Reactions of type (a) are among the most extensively studied, as they include the. synthesis of polyacrylamide Mannich bases, widely employed in water-purification processes. Many other polymeric substrates are, however, succe.ssfully subjected to Mannich reaction (Table 33). Moreover, some polymeric substances need to be suitably functionalized in order to undergo the aminomethylation reaction, as reported for polymeric ketones obtained by oxidation of polyenes." Further macromolecular carbonyl substrates could be provided by interesting vinyl monomers purposely designed to give polymers suitable for Mannich reaction." ... 

As a consequence of the low temperature removal of HC1, thermal decomposition of PVC is a two-step process dehydrochlorination of the polymer to form a polyene macromolecular structure followed by cracking and decomposition of the polyene. 

The thermal decomposition of PVC involves the complete elimination of HQ, leading to the formation of macromolecular residues with polyene sequences. The latter then rearrange and decompose to yield sizeable amoimts of aromatic hydrocarbons. 

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