紫外光谱研究正丁基锂和聚丁二烯基锂的缔合度

Association Number of n-Butyllithium and Polybutadienyllithium by UV-Spectroscopy

建立了一种简便地测定阴离子活性种的紫外光谱的装置和方法,研究了不同浓度的正丁基锂和聚丁二烯基锂在非极性溶剂环己烷中的紫外吸收光谱,发现随着正丁基锂和聚丁二烯基锂的浓度增加,紫外吸收峰向长波方向移动,这与正丁基锂和聚丁二烯基锂的缔合度变化有关。根据浓度与吸收峰波长的关系,推测了正丁基锂的缔合度主要为2,4,6三种,聚丁二烯基锂的缔合度主要为2,4二种。

A simple apparatus and procedures were developed to study the association number ofn -butyllithium and polybutadienyllithium in nonpolar solvents by UV-spectroscopy. The results show that λ_(max) of n-butyllithium and polybutadienyllithium in cyclohexane shifted to longer wavelength with increasing their concentrations, the relationship curve indicated some unchanged regions according to concentration. It might be due to three major association number 2, 4, 6.for n-butyllithium, and two major association number 2, 4 for polybutadienylllthium.