Study on the Development of New Counterions That Permit Living Cationic Polymerization

本研究项目是在“通过亲核反阴离子稳定生长中的碳正离子”这一新概念的基础上，为各种乙烯基单体的活性阳离子聚合开发新的引发体系和反阴离子。1)乙烯基醚活性阳离子聚合的新引发体系研究了五类乙烯基醚活性阳离子聚合的新引发体系，它们由质子酸（引发剂）和弱刘易斯酸（活化剂）的不同组合组成：(a)乙酸衍生物/氯化锌；(b)环取代苯甲酸/氯化锌；(c)卤化氢/卤化锌；(d)三甲基硅基卤化物/卤化锌（含羰基化合物）；(e)碘化氢/金属乙酰丙酮。这些发现表明，“通过亲核反阴离子稳定生长的碳正离子”的概念是活猫的一般原理。苯乙烯的阳离子活性聚合采用甲基磺酸/四氯化锡或苯乙烯-氯化氢/四氯化锡引发体系，在含氯阴离子盐存在的二氯甲烷溶剂中，实现了苯乙烯的阳离子活性聚合。该工艺的发展是重要的，因为这是理想的活性阳离子聚合的第一个例子，这种活性活性低的单体，如苯乙烯，缺乏供电子（阳离子稳定）取代基。3)活性阳离子聚合中生长物的光谱分析氯化锌与乙烯醚加合物（作为生长末端的模型）的混合物采用质子核磁共振波谱直接分析。分析表明：(a)生长端与氯化锌相互作用，从而被激活繁殖；(b)相互作用是一个快速可逆过程；(c)离子中间体参与繁殖反应，其中被激活的生长端攻击单体。少

This research project was to develop new initiating systems and counteranions for living cationic polymerization of a wide variety of vinyl monomers on the basis of a new concept, "stabilization of growing carbocations by nucleophilic counteranions". The following summarizes the achievements of the 2-year project :1) New Initiating Systems for Living Cationic Polymerization of Vinyl EthersFive classes of new initiating systems for living cationic polymerization of vinyl ethers have been developed, which consist of various combinations of a protonic acids (initiator) and a weak Lewis acid (activator) : (a) acetic acid derivative/zinc chloride ; (b) ring-substituted benzoic acid/zinc chloride ; (c) hydrogen halide/zinc halide ; (d) trimethylsilyl halide/zinc halide (with a carbonyl compound) ; and (e) hydrogen iodide/metal acetylacetonate. These findings have shown the concept, "stabilization of growing carbocations by nucleophilic counteranions", to be a general principle for living cat … More ionic polymerization of vinyl monomers.2) Living Cationic Polymerization of StyreneLiving cationic polymorization of styrene has been achieved with use of the methanesulfonic acid/tin tetrachloride or the styrene-hydrogen chloride/tin tetrachloride initiating system in methylene chloride solvent in the presence of a salt with the chloride anion. The development of this process is important in that this is the first example of the ideal living cationic polymerization of such poorly reactive monomers as styrene, which lacks an electron-donating (cation-stabilizing) substituent.3) Spectroscopic Analysis of the Growing Species in Living Cationic PolymerizationMixtures of zinc chloride and the adduct of vinyl ether with a protonic acid (as a model of the growing terminal) were directly analyzed by proton nuclear magnetic resonance spectroscopy. The analysis has revealed : (a) The growing end undergoes interaction with zinc chloride and is thereby activated to propagate ; (b) the interaction is a fast reversible process ; and (c) an ionic intermediate is involved in the propagation reaction where the activated growing end attacks a monomer. Less