Abstract：
We report the catalytic synthesis of 3-hydroxy-2-butanon (acetoin) from acetaldehyde as a key step in the synthesis of C4-molecules from ethanol. Facile C-C bond formation at the α-carbon of the C2 building block is achieved using an N-heterocyclic carbene (NHC) catalyst. The immobilization of the catalyst on a Merrifield\'s peptide resin and its spectroscopic characterisation using solid-state Nuclear Magnetic Resonance (NMR) is described herein. The immobilization of the NHC catalyst allows for process intensification steps and the reported catalytic system was subjected to batch recycling as well as continuous flow experiments. The robustness of the catalytic system was shown over a maximum of 10 h time-on-stream. Overall, high selectivity S>90 % was observed. The observed deactivation of the catalyst with increasing time-on-stream is explained by ex-situ 1H solution-state, as well as 13C and 15N solid-state NMR spectra allowing us to develop a deeper understanding of the underlying decomposition mechanism of the catalyst.
摘要：
我们报道了由乙醛催化合成3-羟基-2-丁酮（丙酮），这是由乙醇合成C4分子的关键步骤。使用N-杂环卡宾(NHC)催化剂在C2结构单元的α-碳处容易地形成C-C键。本文描述了催化剂在Merrifield肽树脂上的固定及其使用固态核磁共振(NMR)的光谱表征。NHC催化剂的固定允许工艺强化步骤,并且对所报道的催化体系进行分批再循环以及连续流动实验。在最多10小时的运行时间内显示了催化体系的稳健性。总的来说,观察到高选择性S>90%。随着运行时间的增加，观察到的催化剂失活可以通过exit1H溶液状态来解释，以及13C和15N固态NMR光谱，使我们能够更深入地了解催化剂的潜在分解机理。
