The selectivity of palladium catalysed hydrogenation can be improved by adding a homogeneous modifier (or poison) such as quinoline to the reaction mixture. Although such selectivity improvement by modifiers (selective catalyst poisoning) has been known for decades, we still know little about them. We, ultimately, cannot select a modifier to improve a particular process. In this study, 21 types of modifiers are screened for the semi-hydrogenation of alkynes with varying catalyst type, reaction time, and target substrate using an automated flow reactor system. All of the studied variables changed affected hydrogenation activity and selectivity confirming the effectiveness of a multi-parameter optimization. 1,10-phenanthroline marked the best selectivity beyond quinoline. The density functional theory (DFT) calculations suggest that 1,10-phenanthroline has a remarkable ability to adsorb on the irregular surface of the catalyst that effects undesirable reaction.

中文翻译：

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用于炔烃半加氢的均相催化剂改性剂：自动流动反应器中的系统筛选和机理计算研究

钯催化氢化的选择性可以通过向反应混合物中加入均相改性剂（或毒物）如喹啉来提高。尽管通过改性剂（选择性催化剂中毒）来提高选择性已经有几十年了，但我们对它们仍然知之甚少。最终，我们无法选择修改器来改进特定过程。在这项研究中，使用自动流动反应器系统筛选了 21 种类型的改性剂，用于使用不同的催化剂类型、反应时间和目标底物对炔烃进行半氢化。所有研究变量的变化都会影响加氢活性和选择性，从而证实了多参数优化的有效性。1,10-菲咯啉的选择性优于喹啉。密度泛函理论 (DFT) 计算表明 1,