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Advancing Polymerization Catalysis by Cooperativity: Dual Catalysis as a Tool to Achieve High Performance at Maximum Simplicity

通过协同性推进聚合催化：双重催化作为以最大简单性实现高性能的工具

基本信息

批准号：
323277263
负责人：
Professor Dr. Stefan Naumann
金额：
--
依托单位：
Institut für Makromolekulare Chemie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/323277263?language=en
关键词：
Advancing Polymerization Catalysis Cooperativity Dual

项目摘要

Dual catalytic pairs consisting of an organocatalyst and a non-modified metal salt will be employed for ring-opening polymerization of O-heterocyclic monomers. The synergistic effects of such combinations will be investigated in a comprehensive study, in an effort to unify and rationalize a field where so far only scattered, yet highly promising reports exist. To achieve this, a finely tuned array of organic components is to be used, ranging from less reactive N-based catalysts (pyridine, 4-dimethylaminopyridine (DMAP)) to typical organocatalysts such as 1,8-diazabicyclo-undec-7-ene (DBU) and including also the more powerful N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs), the latter partially anionic in character. Those are to be applied in a catalytic setup with readily available Lewis acids, such as MgCl2, MgI2, CaCl2, ZnCl2, FeCl3, BiCl3 or YCl3, to polymerize different lactones (i.e. the macrolactone pentadecalactone, the medium size delta-valerolactone and the highly strained beta-butyrolactone). The data derived from such a screening will not only identify suitable combinations for competitive lactone homopolymerization (where dual catalysis can result in massively increased polymerization rates, notably without synthetic efforts), but also for convenient manipulation of the corresponding copolymer composition, as very recent results have revealed. This effect is based on the monomer specific activation by a given Lewis acid and will also be used to generate block-copolyesters by selective activation of inactive/dormant organocatalysts with the aim to realize challenging or unusual block sequences. The overall goal is to establish parameters which allow for an operationally simple synthesis of the desired lactone-based (co)polyester at will, conveniently by employing commercially available Lewis acids and well accessible organic compounds. With this collection of organocatalysts (ca. 20 compounds) and Lewis acids (ca. 10 different metal halides) at hand, the study will also be extended to include other heterocyclic monomers, namely epoxides and carbonates, targeting specifically challenging monomers. On the one hand this will be substituted epoxides (propylene oxide, cyclohexene oxide, styrene oxide) for which organocatalysts alone still suffer from relatively low turnover and slow reactions; a situation where dual catalysis is well positioned to resolve the issue. Secondly, ethylene carbonate will be focused on. This monomer notoriously requires harsh reaction conditions and is prone to CO2-loss, resulting in a mixed carbonate/ethylene oxide backbone. Lewis acid activation in combination with strong nucleophiles is therefore an attractive option to generate polymer with variable carbonate/ethylene oxide content.

由有机催化剂和未改性的金属盐组成的双催化对将用于O-杂环单体的开环聚合。这些组合的协同效应将在一项综合研究中进行调查，以统一和合理化一个迄今为止只有分散但非常有希望的报告存在的领域。为了实现这一点，要使用精细调整的有机组分阵列，范围从反应性较低的N-基催化剂（吡啶、4-二甲基氨基吡啶（DMAP））到典型的有机催化剂如1，8-二氮杂双环-十一碳-7-烯（DBU），并且还包括更强的N-杂环卡宾（NHC）和N-杂环烯烃（NHO），后者在性质上部分阴离子。这些化合物在催化装置中与容易获得的刘易斯酸如MgCl 2、MgI 2、CaCl 2、ZnCl 2、FeCl 3、BiCl 3或YCl 3一起应用，以使不同的内酯（即大环内酯十五内酯、中等尺寸的δ-戊内酯和高度应变的β-丁内酯）脱水。从这样的筛选得到的数据将不仅确定用于竞争性内酯均聚的合适组合（其中双催化可以导致聚合速率大幅增加，特别是在没有合成努力的情况下），而且还用于方便地操纵相应的共聚物组合物，如最近的结果所揭示的。这种效应是基于通过给定的刘易斯酸的单体特异性活化，并且还将用于通过选择性活化非活性/休眠有机催化剂来产生嵌段共聚酯，目的是实现具有挑战性的或不寻常的嵌段序列。总的目标是建立允许通过使用市售刘易斯酸和容易获得的有机化合物方便地随意操作简单地合成所需的内酯基（共）聚酯的参数。有了这个有机催化剂的集合（约。20种化合物）和刘易斯酸（ca. 10种不同的金属卤化物），该研究还将扩展到包括其他杂环单体，即环氧化物和碳酸酯，针对特定的挑战性单体。一方面，这将是取代的环氧化物（环氧丙烷、环氧环己烷、环氧苯乙烯），对于这些环氧化物，单独的有机催化剂仍然遭受相对低的转化率和缓慢的反应;双催化很好地定位于解决该问题的情况。其次，将重点关注碳酸亚乙酯。众所周知，这种单体需要苛刻的反应条件，并且容易损失二氧化碳，从而产生混合的碳酸酯/环氧乙烷骨架。因此，与强亲核试剂组合的刘易斯酸活化是产生具有可变碳酸酯/环氧乙烷含量的聚合物的有吸引力的选择。