Inverted supercritical carbon dioxide/aqueous biphasic media for rhodium-catalyzed hydrogenation reactions
Inverted supercritical carbon dioxide/aqueous biphasic media for rhodium-catalyzed hydrogenation reactions
复制标题
DOI：
10.1002/chem.200601717
复制
发表时间：
2007-01-01
影响因子：
4.3
通讯作者：
Leitner, Walter
中科院分区：
文献类型：
--
作者：
Burgemeister, Katja;Francio, Giancarlo;Leitner, Walter
反相超临界二氧化碳（scCO（2））/水两相体系已被用作Rh催化氢化极性底物的反应介质。手性和非手性亲CO2催化剂有效地固定在scCO（2）作为固定相，而极性底物和产物包含在水中作为移动的相。值得注意的是，产物分离和催化剂再循环在高压釜不减压的情况下进行。催化剂相重复使用多次，转化率高，产品回收率大于85%。在大多数重复性实验中，前两个循环后，发现通过浸出损失的铑和磷低于检测限。通过在顺序优化中使用单纯形算法，用最少的实验优化反应条件。在重复性间歇操作中，获得了高达1600的总周转数（TTN），高达340 h（-1）的周转频率（TOF）和高达99%的ee。设计的催化体系的范围进行了研究，并已实施了连续反应装置。手性配体（R，S）-3-（HF_6）-F-2-BINAPHOS可使衣康酸和2-乙酰胺基丙烯酸甲酯在这些反应介质中具有高度的对映选择性氢化，并具有相当的催化剂稳定性。
An inverted supercritical carbon dioxide (scCO(2))/aqueous biphasic system has been used as reaction media for Rh-catalysed hydrogenation of polar substrates. Chiral and achiral CO2-philic catalysts were efficiently immobilised in scCO(2) as the stationary phase, while the polar substrates and products were contained in water as the mobile phase. Notably, product separation and catalyst recycling were conducted without depressurisation of the autoclave. The catalyst phase was reused several times with high conversion and product recovery of more than 85%. Loss of rhodium and phosphorus by leaching were found to be below the detection limit after the first two cycles in the majority of repetitive experiments. The reaction conditions were optimised with a minimum of experiments by using a simplex algorithm in a sequential optimisation. Total turn-over numbers (TTNs) of up to 1600, turnover frequencies (TOFs) of up to 340 h(-1) and ee's up to 99 % were obtained in repetitive batch operations. The scope of the devised catalytic system has been investigated and a semicontinuous reaction setup has been implemented. The chiral ligand (R,S)-3-(HF6)-F-2-BINAPHOS allowed highly enantioselective hydrogenation of itaconic acid and methyl-2-acetamidoacrylate combined with a considerable catalyst stability in these reaction media.