ansa-Rare-Earth-Metal Catalysts for Rapid and Stereoselective Polymerization of Renewable Methylene Methylbutyrolactones
文献类型：期刊论文
| 作者 | Hu, Yangjian2; Miyake, Garret M.2; Wang, Baoli1; Cui, Dongmei1; Chen, Eugene Y. -X.2 |
| 刊名 | CHEMISTRY-A EUROPEAN JOURNAL
 |
| 出版日期 | 2012-03-01 |
| 卷号 | 18期号:11页码:3345-3354 |
| 关键词 | Homogeneous Catalysis Polymerization Rare-earth Metals Renewable Feedstock Stereoregular Polymers |
| ISSN号 | 0947-6539 |
| DOI | 10.1002/chem.201102677 |
| 英文摘要 | Two ansa-half-sandwich rare-earth-metal (REM) dialkyl complexes supported by an ethylene-bridged fluorenyl (Flu)-N-heterocyclic carbene (NHC) ligand, [M{C2H4(?5-Flu-?1-NHC)}(CH2SiMe3)2] (M=Y, 1; Lu, 2), and a chiral ansa-sandwich samarocene incorporating a C2 ligand, [Sm(?5-C12H8)2(thf)2] (3), have been investigated for the coordinationaddition polymerization of renewable methylene butyrolactones, a-methylene-?-butyrolactone (MBL) and ?-methyl-a-methylene-?-butyrolactone (?MMBL). Both ansa-half-sandwich complexes 1 and 2 exhibit exceptional activity for the polymerization of ?MMBL at room temperature in dimethylformamide (DMF); with a 0.25 mol?% catalyst loading, quantitative monomer conversion can be achieved under 1 min, giving a high turn-over frequency (TOF) of 24?000 h-1. This TOF value represents a rate enhancement, by a factor of 8, 22, or 2400, over the polymerizations by unbridged samarocene [Sm(Cp*)2(thf)2] (Cp*=?5-pentamethylcyclopentadienyl), by bridged ansa-samarocene 3 with C2 ligation, or by the corresponding REM trialkyls without the ansa-Flu-NHC ligation, respectively. Complexes 1 and 2 are also highly active for the polymerization of beta-methyl-a-methylene-?-butyrolactone (beta MMBL), realizing the first example of the metal-mediated coordination polymerization of this monomer and its copolymerization with ?MMBL. More remarkably, the resulting P beta MMBL homopolymer is highly stereoregular (91?% mm) and exhibits a high Tg of 290 degrees C. In sharp contrast, catalysts 1 and 2 have poor activity and efficiency in the polymerization of the parent MBL or the acyclic analog methyl methacrylate. Polymerization and kinetic studies using the most active catalyst (1) of the series have uncovered characteristics of its ?MMBL polymerization and yielded a unimolecular propagation mechanism. A surprising chain-initiation pathway for the polymerization in DMF by 1 has been revealed, and catalytic polymerization in the presence of an organoacid has also been examined. |
| 语种 | 英语 |
| WOS记录号 | WOS:000300972500032 |
| 出版者 | WILEY-V C H VERLAG GMBH |
| 源URL | [http://ir.iccas.ac.cn/handle/121111/47293]  |
| 专题 | 中国科学院化学研究所 |
| 通讯作者 | Cui, Dongmei |
| 作者单位 | 1.Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Peoples R China 2.Colorado State Univ, Dept Chem, Ft Collins, CO 80523 USA |
| 推荐引用方式 GB/T 7714 | Hu, Yangjian,Miyake, Garret M.,Wang, Baoli,et al. ansa-Rare-Earth-Metal Catalysts for Rapid and Stereoselective Polymerization of Renewable Methylene Methylbutyrolactones[J]. CHEMISTRY-A EUROPEAN JOURNAL,2012,18(11):3345-3354. |
| APA | Hu, Yangjian,Miyake, Garret M.,Wang, Baoli,Cui, Dongmei,&Chen, Eugene Y. -X..(2012).ansa-Rare-Earth-Metal Catalysts for Rapid and Stereoselective Polymerization of Renewable Methylene Methylbutyrolactones.CHEMISTRY-A EUROPEAN JOURNAL,18(11),3345-3354. |
| MLA | Hu, Yangjian,et al."ansa-Rare-Earth-Metal Catalysts for Rapid and Stereoselective Polymerization of Renewable Methylene Methylbutyrolactones".CHEMISTRY-A EUROPEAN JOURNAL 18.11(2012):3345-3354. |
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来源：化学研究所
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