106-69-4Relevant articles and documents
-
Griot
, p. 2236,2239 (1958)
-
Catalyst studies on the ring opening of tetrahydrofuran-dimethanol to 1,2,6-hexanetriol
Buntara, Teddy,Melián-Cabrera, Ignacio,Tan, Qiaohua,Fierro, José L.G.,Neurock, Matthew,De Vries, Johannes G.,Heeres, Hero J.
, p. 106 - 116 (2013)
The metal catalyzed hydrogenolysis of the biomass-derived THF-dimethanol to 1,2,6-hexanetriol using heterogeneous catalysts was investigated. Bimetallic Rh-Re catalysts (4 wt% Rh and a Re/Rh (mol. ratio of 0.5) on a silica support gave the best performance and 1,2,6-hexanetriol was obtained in 84% selectivity at 31% conversion (120 C, 80 bar, 4 h); the selectivity reaches a maximum of 92% at 80 C. The product distribution at prolonged reaction times or higher temperatures or both shows the formation of diols and mono-alcohols, indicating that the 1,2,6-hexanetriol is prone to subsequent hydrodeoxygenation reactions. Different silica supports were investigated and optimal results were obtained with an amorphous silica featuring an intermediate surface area and an average mesopore size of about 6 nm. TPR and XPS surface analysis support the presence of mixed Rh and Re particles. The redox Reδ+/ReTotal surface ratio correlates with the conversion in a volcano type dependency. Both gas phase as well as Rh200Re1OH cluster DFT calculations support an acid-metal bifunctional mechanism and explain the products distribution.
Reductive conversion of 5-hydroxymethylfurfural to 1,2,6-hexanetriol in water solvent using supported Pt catalysts
Kataoka, Hiroto,Kosuge, Daichi,Ogura, Keiji,Ohyama, Junya,Satsuma, Atsushi
, p. 60 - 65 (2019/12/24)
One-pot conversion of biomass derived 5-hydroxymethylfurfural (HMF) to 1,2,6-hexanetriol (1,2,6-HT) in water solvent was performed using Pt catalysts supported on various acid-base metal oxides. Pt catalysts supported on hydrotalcite, MgO, and CeO2 showed better yield of 1,2,6-HT and 2,5-bis(hydroxymethyl)-tetrahydrofuran (BHF), while ring-rearranged cyclopentanol derivatives were predominant products on the other Pt catalysts. The product distribution with time course on Pt/hydrotalcite revealed that HMF is at first hydrogenated to BHF, then the following parallel reactions proceed; ring-rearrangement to cyclopentanol derivatives, ring-hydrogenation to BHF, and hydrogenolysis to 1,2,6-HT. When pure hydrotalcite, MgO and CeO2 were physically mixed with Pt/SiO2, the selectivity to 1,2,6-HT was almost zero or less than 10 %. It was suggested that the formation of 1,2,6-HT proceeds at metal-support interface. The effect of metal-support interface was examined by means of IR spectra of adsorbed methanol. It was indicated that both basic property of supports and surface monodentate alkoxide formation are essential for the production of 1,2,6-HT. The maximum yield of 1,2,6-HT (42 %) was obtained using Co-promoted Pt/CeO2 catalysts pre-reduced at 200 °C.
Mechanistic study on -C-O- and -C-C- hydrogenolysis over Cu catalysts: Identification of reaction pathways and key intermediates
Kühne, Benjamin,Vogel, Herbert,Meusinger, Reinhard,Kunz, Sebastian,Kunz, Markwart
, p. 755 - 767 (2018/02/14)
Important petro-based polyol compounds with a longer carbon chain, such as oligohydroxy hexanes (e.g. 1,2- and 1,6-hexanediol or 1,2,6-hexanetriol), require at least three to four synthesis steps. Replacing this complex chemistry by a one-pot reaction via -C-O- bond cleavage from sugars would be a significant breakthrough for the use of renewable feedstocks. Cu is known for its dehydroxylation (deoxygenation) properties, yielding the desired products from sugars. In this joint research between academic and industrial chemistry, we have identified so far unknown intermediate products and present the first mechanism that explains the selective cleavage of OH-groups over copper. Strong interactions between polyols, unsaturated species and the copper surface are observed. Stable five-membered rings are formed with Cu via two vicinal OH-groups of the polyol reactant that makes these OH-groups inert to -C-O- bond cleavage. Adjacent free OH-groups in close proximity to the catalyst are dehydroxylated (deoxygenated). We further show that degradation of polyols not only occurs via commonly cited retro-aldol reactions. The formation of acid intermediates with subsequent decarboxylation is validated as a new pathway for -C-C- bond cleavage to short-chain polyols and CO2. The proposed mechanisms for -C-O- and -C-C- bond cleavage elucidate why hydrogenolysis reactions require high hydrogen pressure (up to 200 bar) to suppress the degradation of sugars and obtain high yields of deoxy C6 products. With this knowledge, the improvement of a standard commercial Cu-RANEY catalyst under optimized reaction conditions was shown. In contrast to alumina-supported Cu, the Cu-Al alloy in a RANEY-type catalyst shows selective -C-O- bond cleavage properties while maintaining the C6 carbon chain. These new insights into the transformation of sugars to value added commodities show the potential for new approaches in future biorefinery concepts.
