A study on the rules of ligands in highly efficient Ru–amide/AC catalysts for acetylene hydrochlorination†
To explore the role of substituents on ligands in the modification of metal catalysts, a series of Ru–amide/AC catalysts are synthesized with various amide ligands derived from formamide and assessed for acetylene hydrochlorination. Activity evaluation reveals a rule that replacing a hydrogen on formamide with an electron donor substituent can enhance the catalytic performance, while electron withdrawing substituents have the opposite effect. However, formanilide, which violates this law, shows the best modification effect, which is proved to be the effect of steric hindrance by characterization and DFT calculation. Therefore, another rule is concluded that the electron donor ability and steric hindrance of substituents on amide ligands jointly affect the modification effect. Finally, benzanilide, with a superior modification effect, which searched based on the above results, gives strong evidence for the correction of these rules. This work provides a theoretical basis for the search for efficient ligands for acetylene hydrochlorination.