Catalytic dehydrogenation of 1,2- and 1,3-diols

Abstract

Abstract:Described are studies of the dehydrogenation of 1,2-and 1,3-diols in homogenous solutions catalyzed by {[2,5-diphenyl-3,4-ditoluyl-(η 5 -C4CO)]2H}Ru2(CO)4(μ-H) (otherwise known as the Casey/Shvo catalyst). Both in the presence and absence of a dihydrogen acceptor, these reactions led to the analogous α-hydroxyketone as the only organic product. Isotopic labeling studies indicate that this product arises from reversible dehydrogenation/hydrogenation reactions, resulting in formation of the thermodynamically favored α-hydroxyketone. When this catalytic dehydrogenation was carried out in the presence of the rhodium decarbonylation catalyst Rh(dppp)2Cl (dppp = 1,3-bis(diphenylphosphino)propane), modest amounts of carbon monoxide result, suggesting that the dehydrogenation does generate at least some aldehydes that are intercepted by this catalyst. However, the efficiency of the latter reaction is poor.

Chemo- and Regioselective Oxidation of Secondary Alcohols in Vicinal Diols

“…More recently, the catalytic dehydrogenation of 1,2-and 1,3-diols with Casey/Shvo catalyst 2 was studied, with the aim to convert lignocellulose into useful fine chemicals ( Figure 1). 19 When Ford and Weber performed the reaction in a closed vessel, low conversions were obtained (~0.25%). However, refluxing the reaction mixture in diglyme under air resulted in a significant increase (~40% conversion) and they therefore hypothesized that the elevated temperatures facilitate the elimination of H 2 from the catalyst.…”

Ultralow Loading Fe on N-Doped Carbon Nanospheres for Anaerobic Cleavage of C–C Bonds in Biomass Vicinal Diols

“…On the other hand, a parallel scheme of direct dehydrogenation of vicinal diols under an inert gas atmosphere is highly attracted and conceived, in which the C–C bonds of vicinal diols can be cleaved along with the generation of H 2 . , This specific route can be used for synthesizing more valuable products (e.g., imine, amine) by making use of sequent condensation and the H 2 transfer reaction. From this point of view, developing an appropriate catalytic system for the transformation of vicinal diols into targeted aldehydes, ketones, and amines is of great significance.…”

Heterogenization of Homogeneous Ruthenium(II) Catalysts for Carbon-Neutral Dehydrogenation of Polyalcohols

“…The literature contains extensive precedents for catalytic polyalcohol (or polyol) dehydrogenation, including ethylene glycol (EG), , glycerol, − 1,4-butanediol, 1,2-benzenedimethanol, , and 1,2-propanediol (1,2 PDO), which show activity for acceptorless dehydrogenation reactions using a variety of homogeneous Ir, Fe, , Ni, Ru, , and Mn , pincer catalysts. Some of these were proposed as reversible LOHC systems. ,, Notably, EG, with a theoretical HSC of 6.5 wt %, is inexpensive due to its extensive use by the automotive industry as a refrigerant.…”