Unexpected CO Dependencies, Catalyst Speciation, and Single Turnover Hydrogenolysis Studies of Hydroformylation via High Pressure NMR Spectroscopy
Unexpected CO Dependencies, Catalyst Speciation, and Single Turnover Hydrogenolysis Studies of Hydroformylation via High Pressure NMR Spectroscopy
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DOI：
10.1021/jacs.6b12533
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发表时间：
2017-02-22
影响因子：
15
通讯作者：
Landis, Clark R.
中科院分区：
文献类型：
--
作者：
Brezny, Anna C.;Landis, Clark R.
铑双（二氮磷杂环戊烷）（BDP）催化的苯乙烯加氢反应对CO浓度敏感，并通过适度的气体压力的变化影响显着不同的动力学制度。威斯康星州高压NMR反应器（WiHP-NMRR）使得能够在这些不同的制度中观察催化剂形态的变化。催化剂形态和产品分布之间的明显差异，使我们报告的第一个直接的，非催化定量观察酰基二羰基氢解。这些实验的分析和建模表明，并非所有的催化剂都通过停止循环的中间体分流，这导致了选择性的急剧失配。本文中的数据突出了Rh（BDP）催化加氢的复杂动力学。在这种情况下，复杂性来自竞争动力学和热力学偏好，涉及酰基单和二羰基中间体的形成和异构化以及它们氢解得到醛。
Rhodium bis(diazaphospholane) (BDP) catalyzed hydroformylation of styrene is sensitive to CO concentration, and drastically different kinetic regimes are affected by modest changes in gas pressure. The Wisconsin High Pressure NMR Reactor (WiHP-NMRR) has enabled the observation of changes in catalyst speciation in these different regimes. The apparent discrepancy between catalyst speciation and product distribution led us to report the first direct, noncatalytic quantitative observation of hydrogenolysis of acyl dicarbonyls. Analysis and modeling of these experiments show that not all catalyst is shunted through the off-cycle intermediates and this contributes to the drastic mismatch in selectivities. The data herein highlight the complex kinetics of Rh(BDP) catalyzed hydroformylation. In this case, the complexity arises from competing kinetic and thermodynamic preferences involving formation and isomerization of the acyl mono- and dicarbonyl intermediates and their hydrogenolysis to give aldehydes.