离子液体介质中钌纳米粒子催化苯乙酮及其衍生物的不对称加氢反应

采用水溶性三(间-磺酸钠苯基)膦(TPPTS)作稳定剂, 在离子液体1-丁基-3-甲基-咪唑四氟硼酸盐([BMIM]BF4)或1-丁基-3-甲基-咪唑对甲基苯磺酸盐([BMIM][p-CH3C6H4SO3])介质中用氢气还原RuCl3·3H2O, 得到钌纳米粒子. 将此钌纳米粒子与(1S, 2S)-1,2-二苯基乙二胺(简称(1S, 2S)-DPEN)、KOH在离子液体/异丙醇介质中原位生成一种不对称加氢催化剂, 用于催化苯乙酮及其衍生物的不对称加氢反应. 实验结果表明, 离子液体介质中的纳米钌催化剂体系具有良好的催化活性和对映选择性. 在优化反应条件下, 催化苯乙酮获得了100%的转化率和79.1%的对映选择性. 并且产物经正己烷萃取后, 含有钌纳米粒子的离子液体可以循环使用.

Asymmetric Hydrogenation of Acetophenone and Its Derivatives Catalyzed by Ruthenium Nanoparticles in Ionic Liquid Media

Reduction of RuCl3·3H2O with hydrogen in ionic liquid [BMIM]BF4(1-butyl-3-methylimidazolium tetrafluoroborate) or [BMIM][p-CH3C6H4SO3] (1-butyl-3-methylimidazolium p-methylphenylsulfonate) medium using P(m-C6H4SO3Na)3 (TPPTS) as stabilizer yielded ruthenium nanoparticles. Further treatment of the Ru nanoparticles with chiral modifier (1S, 2S)-1,2-diphenyl-1,2-ethylene-diamine((1S, 2S)-DPEN) and KOHin ionic liquid/i-PrOH mixed solvent resulted in a novel immobilized chiral catalyst which can asymmetrically hydrogenate acetophenone and its derivatives. 100%conversion and 79.1%ee (enantiomeric excess) were obtained for acetophenone under optimized conditions. The catalyst immobilized in ionic liquid not only exhibits excellent reactivities and enantioselectivities in asymmetric hydrogenation of acetophenone and its derivatives, but also can be recycled and reused by simple extraction with n-hexane.