Active carbon(AC)-supported AuCl_(3)catalysts are considered the most promising materials for acetylene hydrochlorination.However,there is no consensus on the reaction mechanism.In this paper,the mechanism and reactio...Active carbon(AC)-supported AuCl_(3)catalysts are considered the most promising materials for acetylene hydrochlorination.However,there is no consensus on the reaction mechanism.In this paper,the mechanism and reaction steps of Au_((I))-catalyzed acetylene hydrochlorination have been investigated by theoretical calculations.The results show that C_(2)H_(2)assists in the electrophilic addition of HCl,facilitating a change between the Au_((I))and Au_((III))redox couple.The linear structure of AuCl is proposed to form a tetracoordinated five-membered ring transition state,which is accompanied by the oxidation of Au from Au_((I))to Au_((III)).Besides,we explored and compared the reactivity and energy difference between Au_((III))-and Au_((I))-catalyzed acetylene hydrochlorination.The DFT calculations indicate that a strong combination between the Au center and ligands and the favorable hydrogen-transfer angle(close to 180°)significantly enhance the activity of the AuCl_(3)/AC catalyst.We also investigated the change from AuCl_(3)to AuCl,which suggests that the process of decomposition of AuCl_(3)to AuCl is highly possible.These understandings and explanations also open up an intriguing route to design a novel ligand,which is promising to maximize catalytic performance in acetylene hydrochlorination by increasing the stability of Au_((III))in the catalytic cycle.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,21878162,21603107 and 21978137)dedicated to the 100th anniversary of Nankai University.
文摘Active carbon(AC)-supported AuCl_(3)catalysts are considered the most promising materials for acetylene hydrochlorination.However,there is no consensus on the reaction mechanism.In this paper,the mechanism and reaction steps of Au_((I))-catalyzed acetylene hydrochlorination have been investigated by theoretical calculations.The results show that C_(2)H_(2)assists in the electrophilic addition of HCl,facilitating a change between the Au_((I))and Au_((III))redox couple.The linear structure of AuCl is proposed to form a tetracoordinated five-membered ring transition state,which is accompanied by the oxidation of Au from Au_((I))to Au_((III)).Besides,we explored and compared the reactivity and energy difference between Au_((III))-and Au_((I))-catalyzed acetylene hydrochlorination.The DFT calculations indicate that a strong combination between the Au center and ligands and the favorable hydrogen-transfer angle(close to 180°)significantly enhance the activity of the AuCl_(3)/AC catalyst.We also investigated the change from AuCl_(3)to AuCl,which suggests that the process of decomposition of AuCl_(3)to AuCl is highly possible.These understandings and explanations also open up an intriguing route to design a novel ligand,which is promising to maximize catalytic performance in acetylene hydrochlorination by increasing the stability of Au_((III))in the catalytic cycle.
