We describe herein an efficient microwave-assisted aqueous biphasic dehydration of carbohydrates to 5-hydroxymethylfurfural (HMF). The effects of several alkali metal salts in aqueous phase, organic solvents as an extractive phase and Lewis acids are evaluated on the reaction. Specifically, starting from fructose, the use of bromide salts in aqueous phase and the common organic solvent MeCN or lignocellulose-derived g-valerolactone (GVL) as organic extractors are highly beneficial, leading to excellent HMF yields of up to 91% with HCl as a Brønsted acid catalyst. In conjunction with an isomerization catalyst, the method was applicable to glucose as well as various disaccharides and cellulose, affording HMF in notably good yields, particularly with GVL as an extractor and reusable Amberlyst-38(wet) as an acid catalyst. The exceptionally high HMF yields obtained in aqueous solutions is attributed to the combined effect of the biphasic reaction system and the application of microwaves, which ensures short reaction times and minimized by-product formation thereof.

The effect of salts and Brønsted acids on the Lewis acid (CrCl3⋅6 H2O)‐catalyzed glucose dehydration to 5‐hydroxymethylfurfural (HMF) in aqueous media are described. We show that the reaction with bromide salts in place of chlorides leads to higher HMF yields. The influence of salts can be attributed to the anions in solution, specifically to the bromide anions enhancing the fructose dehydration step. Additionally, we demonstrate that the reaction kinetics are governed strongly by acidity. Although the fructose dehydration step is accelerated by the addition of Brønsted acids, even on a catalytic scale, a significant retardation of the glucose conversion rate results in a substantial drop in HMF yields. The suppression in glucose‐to‐fructose isomerization rate with increasing acidity is ascribed to the restrained formation of the chromium–glucose chelate complex during the reaction.

Solvent-free NaOH catalyzed aldol condensation of biomass-derived 5hydroxymethyl furfural (HMF) and furfural with methyl isobutyl ketone (MIBK) was studied, producing branched C11 and C12 furan compounds in high yields of up to 96%.Through use of a Pd/C and Eu(OTf)3 catalytic system, the condensation products of the bio-based starting materials were further hydrodeoxygenated (HDO) in one-step to biofuel compatible branched alkanes 2-methylundecane (3) and 2-methyldecane (4) in excellent yields of 90% and 98%, respectively. In the one-step HDO developed herein, the variation of solvent had a significant effect on the reaction route and degree of conversion of furans to alkanes in the HDO process. Very high overall yields of alkanes 3 (86%) and 4 (94%) were obtained starting from the biomass-based HMF and furfural.

Herein, we report an efficient transition metal triflate catalyzed approach to convert biomass-based compounds, such as monoterpene alcohols, sugar alcohols, octyl acetate and tea tree oil, to their corresponding olefins in high yields. The reaction proceeds through C-O bond cleavage under solventfree conditions, where the catalytic activity is determined by the oxophilicity and the Lewis acidity of the metal catalyst. In addition, we demonstrate how the oxygen containing functionality affects the formation of the olefins. Furthermore, the robustness of the used metal triflate catalysts, Fe(OTf) 3 and Hf(OTf) 4 , is highlighted by their ability to convert an over 2400-fold excess of 2-octanol to octenes in high isolated yields.

the optimizedc onditions of solvent andb ase catalyst in hand, the one-pot dehydrationo ff ructosea nd the condensation sequencew ithv ariousk etones afforded the products in good overall yields over two steps. The scope of the process was expanded to more complex carbohydrates, such as glucose, lactose, sucrose, cellobiose, and inulin.M oreover, by fine-tuning the reaction conditions, the one-pot methodology in which we used inulin as the substrate was highly efficient if applied to variousother important reactions, such as oxidation, reduction, and Cannizzaroa nd Baylis-Hillman reactions, which rendered the corresponding furan derivatives in high overall yields.Scheme1.HMF as ap latform chemicalfor the production of valuable furanic compounds.