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Novel Living Cationic Polymerizations via・pi-Ligand Systems

通过·pi-配体系统进行新型活性阳离子聚合

基本信息

批准号：
06453149
负责人：
SAWAMOTO Mitsuo
金额：
$ 5.25万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06453149/
关键词：
Cationic Polymerization Living polymerization pi-ligand system Growing Carbocation Polymerization Catalysts Vinyl Ether Stirene Lewis Acid イミダゾール

项目摘要

This 2-year research project consisted of two major objectives :(a) To develop novel initiating systems for living cationic polymerizations based on the new concept, "carbocation stabilization via pi-ligand systems" ;(b) To analyze the growing species in these living polymerizations by NMR.1.Search of pi-Ligand Systems and New Initiating SystemsAn extensive search of pi-ligand systems revealed the following three classes of compounds to be suitable for living cationic polymerization of stirene and vinyl ethers :(1) pi-Ligand systems in counteranions : tetraphenylborate and related anions ;(2) pi-Ligand systems in additives : imidazole and related nitrogen-nucleophiles ;(3) pi-Ligand systems in activators : titanium halides with phenoxy ligands.2.Direct In-Situ NMR Analysis on Living Cationic PolymerizationModel reactions of these living processes were analyzed, directly and in-situ, by multinuclear NMR spectroscopy. The initial phase established that this method is highly effective to detect and analyze he growing carbocations, for the first time in this field. The following analysis revealed that in the living processes, the cation concentration is remarkably reduced by thepi-ligand systems, which is due to their strong interaction with the activators, either inter- (class 1 and 2) or intramolecularly (class 3) so as to modulate their Lewis acidity. This effect in turn stabilizes the growing carbocations and thereby suppresses chain transfer and other side-reactions.Thus, this research has established the concept "carbocation stabilization via pi-ligand systems" is a general principle to achieve living cationic polymerizations.

这个为期两年的研究项目包括两个主要目标：(a)根据“通过配体系统稳定碳正离子”的新概念，为活性阳离子聚合开发新的起始系统；(b)用nmr - 1分析这些活聚合体中的生长物种。对pi配体体系的广泛研究揭示了以下三类化合物适合于乙烯醚和乙烯醚的活性阳离子聚合：(1)反阴离子中的pi配体体系：四苯基硼酸盐和相关阴离子；(2)添加剂中的pi-配体体系：咪唑和相关的亲氮试剂；(3)活化剂中的pi配体体系：含苯氧配体的卤化钛。活性阳离子聚合的直接原位核磁共振分析通过多核磁共振波谱直接和原位分析了这些活性过程的模型反应。初步证实了该方法对生长中的碳正离子的检测和分析是非常有效的，在该领域尚属首次。下面的分析表明，在生命过程中，π配体体系能显著降低阳离子浓度，这是由于它们与活化剂之间（1类和2类）或分子内（3类）的强相互作用，从而调节了它们的刘易斯酸度。这种作用反过来稳定生长的碳正离子，从而抑制链转移和其他副反应。因此，本研究确立了“通过配体体系稳定碳阳离子”的概念是实现活阳离子聚合的一般原理。