烷基铝/氢化铝锂还原体系还原液体端羧基氟橡胶

Reduction of Liquid Carboxyl-terminated Fluorine Rubber by Alkyl Aluminum/Lithium Aluminum Hydride Reduction System

采用两种还原体系二异丁基氢化铝(DIBAl-H)/氢化铝锂(LiAlH_(4))和三异丁基铝[Al(i-Bu)_(3)]/LiAlH_(4),将液体端羧基氟橡胶(LTCFs)还原得到液体端羟基氟橡胶(LTHFs)。傅里叶变换红外光谱、核磁共振氢谱和核磁共振氟谱分析均表明,两种还原体系均能将LTCFs中的碳-碳双键和羧基分别还原成碳-碳单键和羟基。进一步对比两种还原体系的还原能力发现,DIBAl-H/LiAlH_(4)更适合还原LTCFs,且在反应温度为60℃、反应时间为8 h、羰基/LiAlH_(4)/DIBAl-H物质的量比为1/1/2的最优条件下LTCFs的还原率可达到88%。与传统强还原剂LiAlH_(4)相比,DIBAl-H/LiAlH_(4)可降低反应温度,且减小还原剂用量。

In this study,liquid hydroxyl-terminated fluorine rubber(LTHFs)was prepared by reduction of liquid carboxy-terminated fluorine rubber(LTCFs)by using two reduction systems:diisobutylaluminum hydride(DIBAl-H)/lithium aluminum hydride(LiAlH_(4))and triisobutylaluminum hydride[Al(i-Bu)_(3)]/ LiAlH_(4).Fourier transform infrared spectroscopy,nuclear magnetic resonance hydrogen spectroscopy and nuclear magnetic resonance fluorine spectroscopy analysis showed that both reduction systems could reduce the carbon-carbon double bond and carboxyl group in LTCFs to carbon-carbon single bond and hydroxyl group,respectively.Further comparing the reducing capacity of the two reduction systems,it was found that DIBAl-H/LiAlH_(4) was more suitable for LTCFs reduction,and the reduction rate could reach 88%at the optimal condition in which the reaction temperature was 60℃,the reaction time was 8 h and the molar ratio of COOH/LiAlH_(4)/DIBAl-H was 1/1/2.Compared with the traditional strong reducing agent LiAlH_(4),DIBAl-H/LiAlH_(4) could reduce the reaction temperature and reduce the amount of reducing agent.