Synthesis of Poly( -ketone) Using New Polymerization Reaction

聚(β-酮)是一类在碳-碳主链上交替具有酮基的重要生物聚合物。它们被称为“多酮”或“乙酰生素”，它们是参与植物芳香天然产物生物合成的前体。本研究采用一种新的聚合方法合成具有明确结构的聚β-酮，然后对产物进行酸解。异丙氧基乙炔在WCl6和MoCl5等过渡金属催化剂存在下聚合，得到棕色材料。分离得到的聚合物经核磁共振和红外光谱确证为聚(异丙氧基乙炔)。以WCl6为催化剂，对叔丁氧基乙炔进行聚合，得到了含有少量异构化单元的聚合物。然而，酸性较弱的催化剂W(OCH6)nCllt；6-n&gt；(n=4，5)几乎只能得到所需的聚合物。室温下，在盐酸和二氧六环的混合液中，对聚(叔丁氧基乙炔)进行了水解性研究。产物的红外光谱表明，聚(叔丁氧基乙炔)很容易被水解，从而得到相应的聚β-酮。另一方面，聚(异丙氧基乙炔)对酸解的反应较弱。

Poly(beta-ketones) are a class of biologically important polymers having keto groups alternatively in the carbon-carbon main chain. They are called "poly-ketides" or "acetogenins", which are involved as precursor in the biosynthesis of aromatic natural products in plants. The present study deals with synthesis of poly (beta-ketones) having a well-defined structure by a new method of polymerization followed by acid-hydrolysis of the product polymers.Isopropoxyacetylene is polymerized in the presence of transition metal catalyst such as WCl_6 and MoCl_5 to give brownish materials. The structure of the isolated polymers has been confirmed as poly(isopropoxyacetylene) by NMR and IR spectroscopy. The polymerization of t-butoxyacetylene by WCl_6 catalyst gave polymer containing a small amount of an isomerized unit. The less acidic catalysts, W(OCH_6)_nCl_<6-n> (n=4,5), however, yielded desired polymer almost exclusively. The hydrolysis of poly(t-butoxyacetylene) was carried out in a mixture of hydrochloric acid and dioxane at room temperature. The IR spectrum of the product indicated that poly(t-butoxyacetylene) was easily hydrolyzed to afford the corresponding poly(beta-ketone) efficiently. On the other hand, poly (isopropoxy acetylene) was less reactive toward the acid hydrolysis.