Theoretical study on molecular mechanism of aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformyfuran catalyzed by VO with counterpart anion in ,-dimethylacetamide solution

• Published in: RSC advances 2021-12, Vol.11 (63), p.39888-39895
• Main Authors: Si, Zhen-Bing, Xiong, Jin-Shan, Qi, Ting, Yang, Hong-Mei, Min, Han-Yun, Yang, Hua-Qing, Hu, Chang-Wei
• Format: Article
• ISSN: 2046-2069
• DOI: 10.1039/d1ra07297h

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 2 + with counterpart anion in N , N -dimethylacetamide (DMA) solution have been theoretically investigated. In DMA solution, the stable VO 2 + -containing complex is the four-coordinated [V(O) 2 (DMA) 2 ] + species. For the gross reaction of 2HMF + O 2 → 2DFF + 2H 2 O, there are three main reaction stages, i.e. , the oxidation of the first HMF to DFF with the reduction of [V(O) 2 (DMA) 2 ] + to [V(OH) 2 (DMA)] + , the aerobic oxidation of [V(OH) 2 (DMA)] + to the peroxide [V(O) 3 (DMA)] + , and the oxidation of the second HMF to DFF with the reduction of [V(O) 3 (DMA)] + to [V(O) 2 (DMA) 2 ] + . The rate-determining reaction step is associated with the C-H bond cleavage of -CH 2 group of the first HMF molecule. The peroxide [V(O) 3 (DMA)] + species exhibits better oxidative activity than the initial [V(O) 2 (DMA) 2 ] + 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) 2 (DMA) 2 ] + species. The rate-determining reaction step is associated with the C-H bond cleavage of -CH 2 group of the first HMF molecule oxidized by [V(O) 2 (DMA) 2 ] + species, while counteranion Cl − exhibits catalytically promotive effect.