Alkoxyoxirane, a Unique Cyclic Monomer: Controlled Cationic Homopolymerization Mediated by Long-Lived Species and Copolymerization with Vinyl Ether via Alkoxy Group Transfer
Alkoxyoxirane, a Unique Cyclic Monomer: Controlled Cationic Homopolymerization Mediated by Long-Lived Species and Copolymerization with Vinyl Ether via Alkoxy Group Transfer
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烷氧基环氧乙烷，一种独特的环状单体：由长寿命物质介导的受控阳离子均聚以及通过烷氧基转移与乙烯基醚的共聚
DOI：
10.1021/ma502151q
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发表时间：
2014
期刊：
影响因子：
5.5
通讯作者：
and Sadahito Aoshima
中科院分区：
文献类型：
--
作者：
Arihiro Kanazawa;Shungo Kanda;Shokyoku Kanaoka;and Sadahito Aoshima
1-甲氧基-2-甲基环氧丙烷(MOPO)是一种可以通过开环方式在烷氧基附近生成碳正离子的烷氧基环氧烷，它可以在金属氯化物作为Lewis酸催化剂的情况下进行可控聚合。引发剂体系的选择是控制环氧乙烷均聚成功的关键，GaCl3/THF体系是引发剂的最佳组合。此外，以CF3SO3H/nBu4NI为引发体系时，蒙脱土与异丙基乙烯基醚(IPVE)的共聚反应生成了长寿命物种。令人惊讶的是，反应是通过IPVE单元中的烷氧基转移进行的。更具体地说，在IPVE衍生的碳正离子与MOPO发生交叉反应后，倒数第二个IPVE单元上的异丙氧基转移到了MOPO衍生的传播阳离子上。这种类型的反应产生侧基，该侧基具有具有异丙氧基的开环Mompo结构。通过“烷氧基转移”机制生成的共聚物是本研究中共聚反应所特有的，并通过1H、13C和2D核磁共振分析以及产物的酸解和随后的再缩合反应得到证实。
1-Methoxy-2-methylpropylene oxide (MOMPO), an alkoxyoxirane that can generate a carbocation adjacent to an alkoxy group via ring-opening, was demonstrated to polymerize in a controlled manner with the use of a metal chloride as a Lewis acid catalyst. The choice of the initiating system is critical for the successful controlled homopolymerization of this alkoxyoxirane; a GaCl3/THF system was observed to be the best combination for the initiating system. Furthermore, the copolymerization of MOMPO with isopropyl vinyl ether (IPVE) generated long-lived species when CF3SO3H/nBu4NI was used as the initiating system. Surprisingly, the reaction proceeded via the transfer of the alkoxy group in the IPVE unit. More specifically, the isopropoxy group at the penultimate IPVE unit transferred to the MOMPO-derived propagating cation after the crossover reaction from the IPVE-derived carbocation to MOMPO. This type of reaction creates a side group that possesses the ring-opened MOMPO structure with the isopropoxy group. The generation of copolymers via the “alkoxy-group transfer” mechanism is unique to the copolymerization in this study and was confirmed by1H,13C, and 2D NMR analyses and by the acid hydrolysis and subsequent reacetalization reactions of the products.