Synthesis of Poly( -ketone) Using New Polymerization Reaction

聚（β-酮）是一类在碳-碳主链中交替地具有酮基的生物重要聚合物。它们被称为“聚酮化合物”或“乙酸配基”，其作为前体参与植物中芳香族天然产物的生物合成。本文研究了以异丙氧基乙炔为原料，在过渡金属催化剂（如WCl_6和MoCl_5）存在下，通过聚合反应和酸水解反应合成具有明确结构的聚β-酮。通过核磁共振和红外光谱证实了聚合物的结构为聚异丙氧基乙炔。以WCl_6为催化剂进行叔丁氧乙炔的聚合，得到了含有少量异构化单元的聚合物。W（OCH_6）_nCl_<6-n>（n= 4，5）催化剂的酸性较低，但几乎只生成所需的聚合物。聚叔丁氧乙炔在盐酸和二氧六环的混合溶液中于室温下进行水解。产物的红外光谱表明，聚叔丁氧乙炔易于水解，有效地生成了相应的聚β-酮。另一方面，聚（异丙氧基乙炔）对酸水解反应性较低。

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.