Ying Duan,Chi Zhang,Dongsheng Deng,Dong Sui,Xiaohan Gao,Yanliang Yang
The rearrangement of furan rings for valuable chemicals is an important topic for biomass conversion. In this study, 2,5-di(hydroxymethyl)furan (BHMF) was selectively converted to 6-methyldihydro-2H-pyran-3(4H)-one (MDPO) and 1-hydroxy-2,5-hexanedione (HHD) under atmospheric H2 pressure in water. The selectivity to MDPO or HHD could be regulated by a catalyst. The parameters (temperature, pH, catalyst loading, and BHMF concentration) for the transformation of BHMF were studied. The selectivity for the transformation of BHMF was very sensitive to the reaction conditions, especially for the conversion of BHMF to MDPO. 68% selectivity to MDPO on Pd/C and 72% selectivity to HHD on Rh/C were achieved under the optimized conditions. Both Pd/C and Rh/C could be reused at least 5 times without the loss of activity. The fresh and used Pd/C and Rh/C were characterized by XRD, XPS, SEM, TEM, EDS mappings and ICP-OES to study the changes during the reaction. The reaction process was studied through controlled experiments, and 6-methylene-2H-pyran-3(6H)-one (MEPO) and 6-hydroxy-6-methyl-2H-pyran-3(6H)-one (HMPO) were identified as intermediates. A reasonable reaction mechanism was proposed and the different selectivity to MDPO and HHD was well explained based on the controlled experiments and DFT calculations. The conditional sensitivity for the selectivity to MDPO and HHD could also be interpreted by the proposed reaction pathway.
Yong-Jian Xu,Jing Shi,Wei-Peng Wu,Rui Zhu,Xing-Long Li,Jin Deng,Yao Fu
In this paper, Cp*Ir (III) Complex and acid co-catalyst system was developed. By using Cp*Ir and γ-Al 2 O 3 (Lewis acid), 5-hydroxymethylfurfural (5-HMF) can be converted efficiently to 3-hydroxymethyl cyclopentanone (HCPN). Meanwhile, Cp*Ir and Brønsted acid can promote conversion of 5-HMF to 1-Hydroxy-2,5-hexanedione (HHD). The effect of Lewis acid and Brønsted acid on the hydrogenation of furan derivatives was studied. Mechanism of conversion of 5-HMF to HCPN was discussed in detail and mechanism proposed by our predecessors was revised. Instead of being an intermediate for the formation of HCPN, it is believed that, HHD is a product of another reaction pathway. HHD condensed via Aldol reaction to produce 3-methylcyclopenten-2-ol-1-one (MCP) instead of HCPN. Under the promotion of Lewis acid, 5-HMF firstly convert to the precursor of HHD. After that, the reaction is through 4 π-electrocyclic ring closure process and HCPN was formed ultimately. Furthermore, we found that our Cp*Ir and acid co-catalyst system is suitable for a variety of furfural compounds. By using Cp*Ir, Brønsted acid can promote conversion of furfural compounds to straight chain ketones and Lewis acid can promote the rearrangement of furfural compounds to cyclopentanone derivatives.
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