R-Cl/SnCl4/n-Bu4NCl-induced direct living cationic polymerization of naturally-derived unprotected 4-vinylphenol, 4-vinylguaiacol, and 4-vinylcatechol in CH3CN
R-Cl/SnCl4/n-Bu4NCl-induced direct living cationic polymerization of naturally-derived unprotected 4-vinylphenol, 4-vinylguaiacol, and 4-vinylcatechol in CH3CN
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R-Cl/SnCl4/n-Bu4NCl 诱导天然衍生的未保护的 4-乙烯基苯酚、4-乙烯基愈创木酚和 4-乙烯基儿茶酚在 CH3CN 中的直接活性阳离子聚合
DOI：
10.1039/c8py01831f
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发表时间：
2019
影响因子：
4.6
通讯作者：
Masami Kamigaito
中科院分区：
文献类型：
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作者：
Hisaaki Takeshima;Kotaro Satoh;Masami Kamigaito
以烷基氯(R-Cl)为引发剂，MtCln为活泼阳离子聚合的常见引发体系，在n-Bu4NCl等添加剂的存在和不存在的情况下，对天然生成的对香豆酸通过脱羧基反应生成的无保护的4-乙烯基苯酚或对羟基苯乙烯(PHOS)进行了直接阳离子聚合。由对甲氧基苯乙烯(PMOS-HCl)、SnCl4和n-Bu4NCl组成的HCl-加合物引发体系在−40°C下直接在CH3CN中进行活性阳离子聚合，而不使用酚基上的任何保护基团，得到了相对分子质量可控、相对分子质量分布(MWD)较窄的规整的聚(PHO)。即使在苯酚存在下，PMOS-HCl/SnCl4/n-Bu4NCl引发体系对PMOS在CH3CN中的活性阳离子聚合也是有效的，几乎完全抑制了苯酚引起的质子引发和链转移反应等副反应。混合物的1H和119Sn核磁共振分析表明，CH3CN与苯酚和SnCl4都有很强的相互作用，从而阻止了苯酚和SnCl4之间的直接相互作用，抑制了这些副反应。4-乙烯基愈创木酚和4-乙烯基邻苯二酚分别通过天然阿魏酸和咖啡酸的脱羧基进行了类似的直接活性阳离子聚合，在CH3CN中得到了稳定的聚合物(MW/Mn=1.1-1.2)，而不保护苯酚和邻苯二酚基团。
A combination of an alkyl chloride (R–Cl) as an initiator and MtCln as an activator, which is a common initiating system for living cationic polymerizations, was used for the direct cationic polymerization of unprotected 4-vinylphenol or p-hydroxystyrene (pHOS), which were derived from naturally-occurring p-coumaric acid via decarboxylation, in the absence and presence of additives such as n-Bu4NCl. The initiating system consisting of an HCl-adduct of p-methoxystyrene (pMOS–HCl), SnCl4, and n-Bu4NCl induced the direct living cationic polymerization of pHOS in CH3CN at −40 °C without using any protective groups on the phenolic groups and resulted in well-defined poly(pHOS) with controlled molecular weights and narrow molecular weight distributions (MWDs) (Mw/Mn = 1.1–1.2). The pMOS–HCl/SnCl4/n-Bu4NCl initiating system was also effective for living cationic polymerization of pMOS in CH3CN even in the presence of phenol, where side reactions such as proton initiation and chain-transfer reactions caused by phenol were almost completely suppressed. 1H and 119Sn NMR analyses of the mixtures revealed that CH3CN strongly interacted with both the phenol and SnCl4 and thereby prevented the direct interaction between the phenol and SnCl4, suppressing these side reactions. Similar direct living cationic polymerizations of 4-vinylguaiacol and 4-vinylcatechol, which were obtained via decarboxylation of naturally-occurring ferulic and caffeic acids, respectively, resulted in well-defined polymers (Mw/Mn = 1.1–1.2) in CH3CN without protecting the phenol and catechol groups.