Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands.
Chemistry. 2020 Apr 21;26(23):5297-5302. doi: 10.1002/chem.202000962. Epub 2020 Apr 1.
Paraformaldehyde is an easy-to-handle chemical for the in situ generation of formaldehyde and is, therefore, often used in chemistry, structural biology, or medicine. We have investigated the depolymerization process of paraformaldehyde at different temperatures for the application as C1 surrogate in "CO-free" carbonylation reactions using in situ Raman spectroscopy. Rather surprisingly, it was found that small amounts of commonly applied carbonylation catalysts slow down the depolymerization process significantly. By applying H, O, and P NMR spectroscopy coupled with DFT calculations the inhibition process could be assigned to an electron-withdrawing coordination behavior of the Pd complex at the chain end of the paraformaldehyde chain. This inhibition process can be controlled by the utilized phosphine ligand.
多聚甲醛是一种易于处理的化学物质，可用于原位生成甲醛，因此常用于化学、结构生物学或医学领域。我们使用原位拉曼光谱研究了不同温度下多聚甲醛的解聚过程，以将其作为“无 CO”羰基化反应中的 C1 替代物。令人惊讶的是，我们发现，少量常用的羰基化催化剂会显著减缓解聚过程。通过应用 H、O 和 31P NMR 光谱以及 DFT 计算，我们可以将抑制过程归因于 Pd 配合物在多聚甲醛链末端的链上的吸电子配位行为。这种抑制过程可以通过使用的膦配体来控制。
