- Effect of carbon chain length on catalytic C–O bond cleavage of polyols over Rh-ReOx/ZrO2 in aqueous phase
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Production of linear deoxygenated C4 (butanetriols, -diols, and butanols), C5 (pentanetetraols, -triols, -diols, and pentanols), and C6 products (hexanepentaols, -tetraols, -triols, -diols, and hexanols) is achievable by hydrogenolysis of erythritol, xylitol, and sorbitol over supported-bimetallic Rh-ReOx (Re/Rh molar ratio 0.5) catalyst, respectively. After validation of the analytical methodology, the effect of some reaction parameters was studied. In addition to C–O bond cleavage by hydrogenolysis, these polyols can undergo parallel reactions such as epimerization, cyclic dehydration, and C–C bond cleavage. The time courses of each family of linear deoxygenated C4, C5, and C6 products confirmed that the sequence of appearance of the different categories of deoxygenated products followed a multiple sequential deoxygenation pathway. The highest selectivity to a mixture of linear deoxygenated C4, C5, and C6 products at 80percent conversion was favoured under high pressure in the presence of 3.7wt.percentRh-3.5wt.percentReOx/ZrO2 catalysts (54–71percent under 80 bar) at 200 °C.
- Besson, Michèle,Da Silva Perez, Denilson,Perret, Noémie,Pinel, Catherine,Sadier, Achraf
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- Conversion of l-rhamnose into ten of the sixteen 1- and 6-deoxyketohexoses in water with three reagents: d-tagatose-3-epimerase equilibrates C3 epimers of deoxyketoses
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The efficient isomerization of l-rhamnose [the only cheaply available deoxy hexose] to 1-deoxy-l-psicose, 1-deoxy-d-psicose, 1-deoxy-l-fructose, 1-deoxy-d-fructose, 1-deoxy-l-tagatose, 6-deoxy-l-psicose, 6-deoxy-d-psicose, 6-deoxy-l-fructose, 6-deoxy-d-fructose, and 6-deoxy-l-tagatose is described. The conversion of rhamnose to ten of the sixteen 1- and 6-deoxyketohexoses is accomplished in water in three steps. The range of substrates for d-tagatose-3-epimerase (DTE) is extended to 1- and 6-deoxyketoses. An authentic sample of 6-deoxy-d-psicose is prepared from d-psicose.
- Gullapalli, Pushpakiran,Yoshihara, Akihide,Morimoto, Kenji,Rao, Devendar,Akimitsu, Kazuya,Jenkinson, Sarah F.,Fleet, George W.J.,Izumori, Ken
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supporting information; experimental part
p. 895 - 898
(2010/05/03)
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