硼氢化钠/Ziegler-Natta稀土催化剂组成的还原体系用于还原液体端羧基氟橡胶

NaBH_(4)/Ziegler-Natta Rare Earth Catalyst Reduction System for Reduction of Liquid Terminated-carboxyl Fluoroelastomers

以液体端羧基氟橡胶(LTCFs)为原料,硼氢化钠/Ziegler-Natta稀土催化剂(NaBH_4/Ziegler-Natta)为还原体系,采用一锅法将液体端羧基氟橡胶还原为液体端羟基氟橡胶(LTHFs).采用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(~1H NMR)、核磁共振氟谱(~(19)F NMR)和化学滴定法对液体端羧基氟橡胶和液体端羟基氟橡胶的分子链结构和官能团含量进行了表征.结果表明,液体端羧基氟橡胶中的碳碳双键(—C=C—)和端羧基官能团(—COOH)均被高效地还原为碳碳单键(—C—C—)和端羟基(—OH).与传统硼氢化钠/催化剂还原体系相比,硼氢化钠/Ziegler-Natta催化剂还原体系对LTCFs的还原效果具有催化剂用量小、反应时间短、反应温度低及对—COOH还原能力强等优点.

Sodium borohydride/Ziegler-Natta rare earth catalyst reduction system(NaBH_(4)/Ziegler-Natta)was used to reduce liquid terminated-carboxyl fluoroelastomers(LTCFs).LTCFs were efficiently converted to the corresponding liquid terminated-hydroxyl fluoroelastomers(LTHFs)via a simple one-pot method.The reductive rate of LTHFs was analyzed by chemical titration.The structures of LTCFs and LTHFs were analyzed by Fourier transform infrared spectroscopy(FTIR),1H nuclear magnetic resonance(^(1)H NMR)spectroscopy and ^(19)F nuclear magnetic resonance(19F NMR)spectrocopy.The results show that—C=C—and carboxyl groups of LTCFs were reduced to—C—C—and—OH efficiently at ambient temperature and the reduction rate reached 90%under optimum reaction conditions.