Density Functional Theory Analysis of Anthraquinone Derivative Hydrogenation over Palladium Catalyst.
A density functional theory (DFT) analysis was conducted on the hydrogenation of 2-alkyl-anthraquinone (AQ), including 2-ethyl-9,10-anthraquinone (eAQ) and 2-ethyl-5,6,7,8-tetrahydro-9,10-anthraquinone (H4eAQ), to the corresponding anthrahydroquinone (AQH2) over a Pd6H2cluster. Hydrogenation of H4eAQ is suggested to be more favorable than that of eAQ owing to a higher adsorption energy of the reactant (H4eAQ), lower barrier of activation energy, and smaller desorption energy of the target product (2-ethyl-5,6,7,8-tetrahydro-9,10-anthrahydroquinone, H4eAQH2). For the most probable reaction routes, the energy barrier of the second hydrogenation step of AQ is circa 8 kcal mol-1higher than that of the first step. Electron transfer of these processes were systematically investigated. Facile electron transfer from Pd6H2cluster to AQ/AQH intermediate favors the hydrogenation of C=O. The electron delocalization over the boundary aromatic ring of AQ/AQH intermediate and the electron-withdrawing effect of C=O are responsible for the electron transfer. In addition, a pathway of the electron transfer is proposed for the adsorption and subsequent hydrogenation of AQ on the surface of Pd6H2cluster. The electron transfers from the abstracted H atom (reactive H) to a neighbor Pd atom (PdH), and finally goes to the carbonyl group through the C4atom of AQ aromatic ring (C4).
Key Laboratory for Green Chemica,l Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
Enxian
E
Yuan
Key Laboratory for Green Chemica,l Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.|Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
Li
L
Wang
Key Laboratory for Green Chemica,l Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.|Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
Xiangwen
X
Zhang
Key Laboratory for Green Chemica,l Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
Ren
R
Feng
Key Laboratory for Green Chemica,l Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
Chan
C
Wu
Key Laboratory for Green Chemica,l Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.|Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
Guozhu
G
Li
anthraquinone derivative; density functional calculations; electron transfer; hydrogenation; palladium cluster