Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N -Benzylamide
Anionic Polymerization of (Meth)acrylates with Trialkylsilyl-protected Lithium N -Benzylamide
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(甲基)丙烯酸酯与三烷基甲硅烷基保护的N-苄基酰胺锂的阴离子聚合
DOI：
10.1295/polymj.pj2007029
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发表时间：
2008
期刊：
影响因子：
2.8
通讯作者：
T. Kitayama
中科院分区：
文献类型：
--
作者：
Takehiro Kitaura;T. Kitayama
甲基丙烯酸酯与N-苄基三甲基硅酰胺锂(BnTM NLi)在铝化合物存在下聚合，可得到分子量分布较窄的间规或异规聚甲基丙烯酸酯。这些聚合物的端基分析表明，在聚合物的引发链端定量地引入了苄氨基。聚合的引发剂效率略低于1(0.8-0.9)，提示引发过程中可能存在副反应。甲基丙烯酸甲酯(MMA)与BnTM NLi聚合的粗反应混合物中含有少量的N-苄基甲基丙烯酰胺，这种N-苄基甲基丙烯酰胺应是在聚合引发阶段通过BnTM NLi与MMA的1，2-加成(羰基加成)形成的。原位生成的硅基取代甲基丙烯酰胺不参与进一步的聚合过程，因为形成的聚合物的MALDI-TOF质量分析表明聚合物链中没有相应的单元。用酸化的甲醇终止聚合反应，将保持不变的甲基丙烯酰胺转化为N-苄基甲基丙烯酰胺。因此，可以通过对聚合物中的苄氨基端基和聚合混合物中的N-苄基甲基丙烯酰胺的核磁共振光谱定量来估计引发步骤中的1，4-/1，2-加成选择性。带有大体积三异丙基硅基取代基的锂酰胺BnTIPSNLi完全抑制了1，2-加成反应，从而抑制了甲基丙烯酰胺的生成，而15%的BnTM NLi和2%的BnTBSNLi(叔丁基二甲基硅基)发生了1，2-加成反应。
The polymerization of methacrylates with lithium N-benzyltrimethylsilylamide (BnTMSNLi) in the presence of aluminum compounds afforded syndiotactic or heterotactic polymethacrylates with narrow MWD quantitatively. The end-group analysis of these polymers revealed that benzylamino end-group was quantitatively introduced at the initiating chain-ends of the polymers. The initiator efficiency of the polymerization was slightly lower than unity (0.8–0.9), suggesting possible side reactions in the initiation process. The crude reaction mixture from methyl methacrylate (MMA) polymerization with BnTMSNLi was found to contain a small amount of N-benzylmethacrylamide, which should be formed through the 1,2-addition (carbonyl addition) of BnTMSNLi to MMA in the initiation step of the polymerization. The in situ formed silyl-substituted methacrylamide was not involved in the further polymerization process, as MALDI-TOF mass analysis of the formed polymer indicated the absence of the respective unit in the polymer chain. The methacrylamide remained intact was transformed to N-benzylmethacrylamide when the polymerization was terminated with acidified methanol. Therefore, 1,4-/1,2-addition selectivity in the initiation step could be estimated by NMR spectroscopic quantification of the benzylamino end-group in the polymer and N-benzylmethacrylamide in the polymerization mixture. A lithium amide with bulky triisopropylsilyl substituent, BnTIPSNLi, completely suppressed the 1,2-addition and thus the methacrylamide formation, while 15% of BnTMSNLi and 2% of BnTBSNLi, tert-butyldimethylsilyl derivative, underwent the 1,2-addition.
影响因子：
2.8
作者：
T. Kitayama;Tomohiro Hirano;K. Hatada
通讯作者：
T. Kitayama;Tomohiro Hirano;K. Hatada
影响因子：
3.2
作者：
T. Kitayama;T. Shinozaki;Eiji Masuda;Masanori Yamamoto;K. Hatada
通讯作者：
T. Kitayama;T. Shinozaki;Eiji Masuda;Masanori Yamamoto;K. Hatada