• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Discrete cationic zinc and magnesium complexes for dual organic/organometallic-catalyzed ring-opening polymerization of trimethylene carbonate
【24h】

Discrete cationic zinc and magnesium complexes for dual organic/organometallic-catalyzed ring-opening polymerization of trimethylene carbonate

机译：离散阳离子锌和镁配合物用于碳酸亚丙酯的有机/有机金属双重开环聚合

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We describe herein an original approach for the efficient immortal ring-opening polymerization (iROP) of trimethylene carbonate (TMC) under mild conditions using dual-catalyst systems combining a discrete cationic metal complex with a tertiary amine. A series of new zinc and magnesium cationic complexes of the type [{NNO}M] ~+[anion] ~- ({NNO} ~-=2,4-di-tert-butyl-6-{[(2'-dimethylaminoethyl)methylamino]methyl} phenolate; M=Zn, [anion] -=[B(C _6F _5) _4] ~- (2), [H _2N- {B(C _6F _5) _3} _2] ~- (3), and [EtB(C _6F _5) _3] ~- (4); M=Mg, [anion] ~-=[H _2N{B(C _6F _5) _3} _2] ~- (7)) have been prepared from the corresponding neutral compounds [{NNO}ZnEt] (1) and [{NNO}- Mg(nBu)] (6). Compounds 2-4 and 7 exist as free ion pairs, as revealed by ~1H, ~(13)C, ~(19)F, and ~(11)B NMR spectroscopy in THF solution, and an X-ray crystallographic analysis of the bis(THF) adduct of compound 7, 7·(THF) _2. The neutral complexes 1 and 6, in combination with one equivalent or an excess of benzyl alcohol (BnOH), initiate the rapid iROP of TMC, in bulk or in toluene solution, at 45-60°C (turnover frequency, TOF, up to 25-30000 mol(TMC)·mol(Zn)·h ~(-1) for 1 and 220-240000 mol(TMC)·mol(Mg)·h ~(-1) for 6), to afford H-PTMC-OBn with controlled macromolecular features. ROP reactions mediated by the cationic systems 2/BnOH and 7/BnOH proceeded much more slowly (TOF up to 500 and 3000 mol(TMC)·mol(Zn or Mg)·h ~(-1) at 110°C) than those based on the parent neutral compounds 1/BnOH and 6/BnOH, respectively. Use of original dual organic/organometallic catalyst systems, obtained by adding 0.2-5 equiv of a tertiary amine such as NEt 3 to zinc cationic complexes [{NNO}Zn] ~+[anion] ~- (2-4), promoted high activities (TOF up to 18300 mol(TMC)·mol(Zn)·h ~(-1) at 45°C) giving H-PTMC-OBn with good control over the M _n and M _w/M _n values. Variation of the nature of the anion in 2-4 did not significantly affect the performance of these catalyst systems. On the other hand, the dual magnesium-based catalyst system 7/NEt _3 proved to be poorly effective. It takes two! The combination of a Lewis acidic cationic metal fragment, to activate the monomer, and a tertiary amine, to enhance the nucleophilicity of the protic initiator, generates a highly active catalytic system for the controlled ring-opening polymerization of trimethylene carbonate (see scheme). The role of each component of this original dual-catalyst system has been scrutinized.
机译：我们在本文中描述了一种在温和条件下使用结合离散阳离子金属配合物和叔胺的双催化剂系统有效地进行碳酸三亚甲基酯（TMC）的永生开环聚合（iROP）的原始方法。 [{NNO} M]〜+ [阴离子]〜-（{NNO}〜-= 2,4-二叔丁基-6-{{（（2'- （二甲基氨基乙基）甲基氨基]甲基}酚盐; M = Zn，[阴离子]-= [B（C _6F _5）_4]〜-（2），[H _2N- {B（C _6F _5）_3} _2]〜-（ 3）和[EtB（C _6F _5）_3]〜-（4）; M = Mg，[阴离子]〜-= [H _2N {B（C _6F _5）_3} _2]〜-（7））具有由相应的中性化合物[{NNO} ZnEt]（1）和[{NNO}-Mg（nBu）]（6）制备。化合物2-4和7以游离离子对形式存在，如〜1H，〜（13）C，〜（19）F和〜（11）B NMR光谱在THF溶液中以及X-射线晶体学分析所揭示化合物7、7·（THF）_2的双（THF）加合物。中性配合物1和6与一当量或过量的苄醇（BnOH）结合，可在45-60°C（周转频率，TOF，直至1的25-30000 mol（TMC）·mol（Zn）·h〜（-1）和6）的220-300000 mol（TMC）·mol（Mg）·h〜（-1），得到H-PTMC -OBn具有受控的大分子特征。阳离子系统2 / BnOH和7 / BnOH介导的ROP反应的进行速度要慢得多（TOF在110°C时分别达到500和3000 mol（TMC）·mol（Zn或Mg）·h〜（-1））分别基于母体中性化合物1 / BnOH和6 / BnOH。通过在锌阳离子络合物[{NNO} Zn]〜+ [阴离子]〜-（2-4）中添加0.2-5当量的叔胺（例如NEt 3）而获得的原始有机/有机金属双重催化剂体系，可提高活性（TOF在45°C时高达18300 mol（TMC）·mol（Zn）·h〜（-1））可以使H-PTMC-OBn很好地控制M _n和M _w / M _n值。 2-4阴离子的性质变化不会显着影响这些催化剂体系的性能。另一方面，双重镁基催化剂体系7 / NEt _3被证明是无效的。需要两个！路易斯酸阳离子金属片段（用于活化单体）和叔胺（用于增强质子引发剂的亲核性）的组合产生了高活性催化体系，用于碳酸亚丙酯的受控开环聚合（请参见方案）。已仔细研究了这种原始双催化剂系统中每个组分的作用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号