聚丁二烯链中孤立1,2-单元的两种构型

用¹³C-NMR波谱方法研究聚丁二烯的键接序列结构,在归属¹³C-NMR谱(脂碳谱)中各共振吸收峰时,使用经验方法无疑是十分有效的。然而作者仍然发现有两个小峰4'和8'(图1),它们的归属不能从经验方法得到令人满意的解释。最近一张新的聚丁二烯的¹³C-NMR谱图表明,在6峰的低场方向还有另一谱峰、6'峰存在(图2)。6'峰的出现同样不能通过运用经验方法处理聚丁二烯的键接序列结构得到理解。

Two Configurations of the Isolate 1,2-unit in PBD Chain

Three small peaks 4', 6' and 8' in the aliphatic part of ¹³C-NMR spectrum of polybutadiene (PBD) have been observed. Their appearance is considered to be related with the peaks 4,6 and 8 of the isolate 1,2-unit in PBD and to be a result of the splitting of the latter three peaks, respectively. In order to explanation these results authors of this paper consider that there must exist a new, with a higher energy level, configuration,which would show a certain shielding effect on the C_α and C_γ but decrease the shielding effect on the C_β of the isolate 1,2-unit of PBD chain.