• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Chain-growth versus step-growth mechanisms for the suzuki-heck polymerisation of fluorenyldibromides with potassium vinyl trifluoroborate
【24h】

Chain-growth versus step-growth mechanisms for the suzuki-heck polymerisation of fluorenyldibromides with potassium vinyl trifluoroborate

机译：芴基二溴化物与乙烯基三氟硼酸钾的铃木-heck聚合的链增长与步长增长机理

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

The mechanism of the Suzuki-Heck (SuHe) polymerisation of 2,7-dibromo-9,9-di(n-dodecyl)fluorene (1) with potassium vinyl trifluoroborate (PVTB) for the synthesis of poly(fluorenylene vinylene)s (PFVs) has been investigated. In the first stage, a palladium-catalysed chain-growth AA/B(C)type polycondensation occurs, as evidenced by the linear trend observed when plotting the molecular weights of the polymer formed against the consumption of the monomer. The chaingrowth stage takes place until complete consumption of 1 and allows one to envisage the alternating addition of PVTB (by a Suzuki step) and 1 (by a Heck step) to the growing chain. Such alternating addition seems to proceed through a peculiar catalyst transfer during which the metal is constantly bound to the growing chain, confirmed by MALDI end-group analysis. On prolonging the reaction after the disappearance of 1, a second stage takes place, leading to higher molecular weight polymers, which are formed by the step-growth condensation of the fragments generated in the first stage. The molecular weights of the final PFVs depend on the PVTB/1 feed ratio. Thus, by using a PVTB/1 molar ratio of 1.1, the final PFV was characterised by an M _n of 39600 Da, whereas when using a PVTB/1 molar ratio of 2.0, the final PFV was characterised by an M_n of 13200 Da.
机译：Suzuki-Heck（SuHe）将2,7-二溴-9,9-二（正十二烷基）芴（1）与乙烯基三氟硼酸钾（PVTB）聚合的机理，用于合成聚芴基亚乙烯基（ PFVs）已被调查。在第一步中，发生钯催化的链增长AA / B（C）型缩聚反应，这是根据绘制的聚合物分子量与单体消耗量作图时观察到的线性趋势所证明的。直到整个消耗量为1时，才进行缠结生长阶段，并允许人们设想将PVTB（通过Suzuki步骤）和1（通过Heck步骤）交替添加到生长链中。这种交替的添加似乎是通过特殊的催化剂转移进行的，在该过程中，金属始终与增长的链结合，这已通过MALDI端基分析得到证实。在消失1后延长反应时，发生第二阶段，导致更高分子量的聚合物，其由第一阶段中产生的片段的逐步生长缩合形成。最终PFV的分子量取决于PVTB / 1的进料比。因此，通过使用1.1的PVTB / 1摩尔比，最终的PFV的特征在于M_n为39600 Da，而当使用PVTB / 1的摩尔比2.0时，最终的PFV的特征在于M_n为13200 Da。

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