Geitner Robert, Gurinov Andrei, Huang Tianbai, Kupfer Stephan, Gräfe Stefanie, Weckhuysen Bert M
Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG, Utrecht, The Netherlands.
NMR Spectroscopy group, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands.
Angew Chem Int Ed Engl. 2021 Feb 15;60(7):3422-3427. doi: 10.1002/anie.202011152. Epub 2020 Dec 14.
"CO-free" carbonylation reactions, where synthesis gas (CO/H ) is substituted by C1 surrogate molecules like formaldehyde or formic acid, have received widespread attention in homogeneous catalysis lately. Although a broad range of organics is available via this method, still relatively little is known about the precise reaction mechanism. In this work, we used in situ nuclear magnetic resonance (NMR) spectroscopy to unravel the mechanism of the alkoxycarbonylation of alkenes using different surrogate molecules. In contrast to previous hypotheses no carbon monoxide could be found during the reaction. Instead the reaction proceeds via the C-H activation of in situ generated methyl formate. On the basis of quantitative NMR experiments, a kinetic model involving all major intermediates is built which enables the knowledge-driven optimization of the reaction. Finally, a new reaction mechanism is proposed on the basis of in situ observed Pd-hydride, Pd-formyl and Pd-acyl species.
“无一氧化碳”的羰基化反应，即合成气（CO/H₂）被诸如甲醛或甲酸等C1替代分子所取代，近来在均相催化领域受到了广泛关注。尽管通过这种方法可得到种类繁多的有机物，但对于其精确的反应机理仍知之甚少。在这项工作中，我们使用原位核磁共振（NMR）光谱来揭示使用不同替代分子时烯烃的烷氧基羰基化反应机理。与先前的假设相反，反应过程中未发现一氧化碳。相反，反应是通过原位生成的甲酸甲酯的C-H活化进行的。基于定量NMR实验，构建了一个包含所有主要中间体的动力学模型，这使得能够对反应进行知识驱动的优化。最后，基于原位观察到的钯氢化物、钯甲酰基和钯酰基物种，提出了一种新的反应机理。
