金属有机化学：Homogeneous catalysis (4).ppt

Homogeneous catalysis Hydroformylation Converting terminal alkenes into other organic products. (oxo process) H and HCO are formally added across a double bond. Show reaction Largest-scale industrial process that is homogeneous Mechanism was suggested by Heck and Breslow in 1961. Examine each step in the cycle and characterize the reaction according to type. 18-,16-electron cycling is common. 反应机理一共有5步 反应特点： 反应产物中支链结构更有价值 CH3CH=CH2?CH3CH2CH2CHO 活性催化剂不稳定，难以分离再利用 CO的压力要比较大，对生产设备的要求会比较高 Phosphine modified hydroformylation 支链vs直链？ Union Carbide Hydroformylation Process 以Rh 为金属中心以及体积大的磷配体为催化剂 反应机理会受到什么影响? (Ph3P)3Rh(CO)H 直链/支链比例较大 可以合成水溶性的. Insertion and elimination * 金属中心的反应活性顺序: p259 ? 实际使用的催化剂: HRh(PR3)3CO ? studied first by Wilkinson et al. in 1968 ? 丙烯的氢甲酰化反应条件: UCC: PPh3 / Rh: 400 : 1, T: 85 - 90 °C, p: 15 - 18 bar, n / i: 90 % Ruhrchemie/Rhone Poulenc: TPPTS / Rh = 100 : 1, T = 120 °C, p 20 bar 两种配体: ? Phosphines (P-C-bond) ? Phosphites (P-O-bond) Rh-catalyzed Hydroformylation Gas phase Gas phase Gas phase Hydrocarbon Hydrocarbon Hydrocarbon phase phase phase Aqueous phase Fluorous phase HRh(CO)[PPh3]3 HRh(CO)[P(C6H4SO3Na)3]3 HRh(CO)(P[CH2)2(CF2)5CF3]3)3 Hydroformylation - The Multiphase Approach 为什么是內烯烃? 有趣的原料: Butenes (raffinat-II) 反应活性: Hydroformylation of Internal Olefins 氢醛化反应获得的醛的量 steamcracker low severity catcracker (FCC) gasoil, zeolite steamcracker high severity alkynes 2 4 32 20 7 7 26 2 1 3 22 14 6 5 47 2 alkynes 12 12 37 13 15 11 0,5 Composition of C4-Fractions ? fast isomerisation necessary ? no hydroformylation of internal double bonds ? fast and selective reaction of the terminal olefin Hydroformylation of internal olefins 通过內烯烃得到端醛仍然是挑战 P. W. N. M. van Leeuwen et al., In Rhodium Catalyzed Hydroformylation, P. W. N. M. van Leeuwen, C. Claver, Eds., Kluwer, Dordrecht, 2000, p.57. 这些反应有什么共同点呢？ Life Relies on Chemical Reactions 更高的反应活性和选择性 提高产率节约能源，减小浪费 提高经济效益和生态友好 Catalysis - Important for our Society Prod