Si Zhen-Bing, Xiong Jin-Shan, Qi Ting, Yang Hong-Mei, Min Han-Yun, Yang Hua-Qing, Hu Chang-Wei
College of Chemical Engineering, Sichuan University Chengdu Sichuan 610065 P.R. China
Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University Chengdu Sichuan 610064 P.R. China.
RSC Adv. 2021 Dec 15;11(63):39888-39895. doi: 10.1039/d1ra07297h. eCollection 2021 Dec 13.
Vanadium-containing catalysts exhibit good catalytic activity toward the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformyfuran (DFF). The aerobic oxidation mechanism of HMF to DFF catalyzed by VO with counterpart anion in ,-dimethylacetamide (DMA) solution have been theoretically investigated. In DMA solution, the stable VO -containing complex is the four-coordinated [V(O)(DMA)] species. For the gross reaction of 2HMF + O → 2DFF + 2HO, there are three main reaction stages, , the oxidation of the first HMF to DFF with the reduction of [V(O)(DMA)] to [V(OH)(DMA)], the aerobic oxidation of [V(OH)(DMA)] to the peroxide [V(O)(DMA)], and the oxidation of the second HMF to DFF with the reduction of [V(O)(DMA)] to [V(O)(DMA)]. The rate-determining reaction step is associated with the C-H bond cleavage of -CH group of the first HMF molecule. The peroxide [V(O)(DMA)] species exhibits better oxidative activity than the initial [V(O)(DMA)] species, which originates from its narrower HOMO-LUMO gap. The counteranion Cl exerts promotive effect on the aerobic oxidation of HMF to DFF catalyzed by [V(O)(DMA)] species.
含钒催化剂对5-羟甲基糠醛（HMF）有氧氧化生成2,5-二甲基呋喃（DFF）表现出良好的催化活性。理论上研究了在N,N-二甲基乙酰胺（DMA）溶液中，VO与相应阴离子催化HMF氧化为DFF的有氧氧化机理。在DMA溶液中，稳定的含VO配合物是四配位的[V(O)(DMA)]物种。对于总反应2HMF + O₂ → 2DFF + 2H₂O，有三个主要反应阶段，即第一个HMF氧化为DFF，同时[V(O)(DMA)]还原为[V(OH)(DMA)]；[V(OH)(DMA)]有氧氧化为过氧化物[V(O₂)(DMA)]；第二个HMF氧化为DFF，同时[V(O₂)(DMA)]还原为[V(O)(DMA)]。速率决定反应步骤与第一个HMF分子的-CH基团的C-H键断裂有关。过氧化物[V(O₂)(DMA)]物种比初始的[V(O)(DMA)]物种表现出更好的氧化活性，这源于其更窄的HOMO-LUMO能隙。抗衡阴离子Cl对[V(O)(DMA)]物种催化HMF有氧氧化为DFF有促进作用。
