Rumyantsev Misha, Sitnikov Nikolay S, Somov Nikolay V
†Nizhny Novgorod State Technical University n.a. R.E. Alekseev, 24 minin st., Nizhny Novgorod 603950, Russia.
‡Lobachevsky State University of Nizhni Novgorod, 23 Prospekt Gagarina (Gagarin Avenue), Nizhny Novgorod 603950, Russia.
J Phys Chem A. 2015 May 7;119(18):4108-17. doi: 10.1021/acs.jpca.5b02102. Epub 2015 Apr 24.
An efficient method was developed for the acetalization of secondary alcohols in the presence of simple protic pyridinium salts. Direct correlations between the structure and activity of the synthesized catalysts were described. Stabilization via hydrogen bonding of the hemiacetal intermediate by the pyridine derivatives, along with an appropriate increase in the reaction rate, was revealed. The nature of the observed experimental acceleration of the examined reactions catalyzed by pyridinium salts comprising electron-withdrawing groups at certain positions of the pyridinium ring was studied. In this vein, the interpretation of the hydrogen-bonded pretransition-state complexes and transition-state complexes with strong catalysts was also discussed in terms of partial proton transfer. It was concluded that optimized pretransition-state complexes of the catalyst and reactant are useful for the prediction of catalyst efficiency prior to the experiment.
开发了一种在简单质子吡啶盐存在下对仲醇进行缩醛化反应的有效方法。描述了合成催化剂的结构与活性之间的直接相关性。揭示了吡啶衍生物通过氢键对半缩醛中间体的稳定作用，以及反应速率的适当提高。研究了在吡啶环特定位置含有吸电子基团的吡啶盐催化所考察反应时观察到的实验加速的本质。在此方面，还从部分质子转移的角度讨论了与强催化剂形成的氢键预过渡态络合物和过渡态络合物的解释。得出的结论是，催化剂与反应物的优化预过渡态络合物有助于在实验前预测催化剂效率。
