Pravin P. Upare

An integrated process for the production of 2,5-dimethylfuran from fructose

2,5-Dimethylfuran was successfully produced in 92% overall yield from fructose in 1-butanol through a combination of dehydration over Amberlyst-15 and hydrogenolysis over the Ru–Sn/ZnO catalyst. The environmental favorability of this process, and its unprecedented efficiency, makes it promising from both a green chemistry and an industrial perspective.

Chemical Conversions of Biomass-Derived Platform Chemicals over Copper-Silica Nanocomposite Catalysts.

Biomass and biomass-derived carbohydrates have a high extent of functionality, unlike petroleum, which has limited functionality. In biorefinery applications, the development of methods to control the extent of functionality in final products intended for use as fuels and chemicals is a challenge. In the chemical industry, heterogeneous catalysis is an important tool for the defunctionalization of functionalized feedstocks and biomass-derived platform chemicals to produce value-added chemicals. Herein, we review the recent progress in this field, mainly of vapor phase chemical conversion of biomass-derived C4 -C6 carboxylic acids and esters using copper-silica nanocomposite catalysts. We also demonstrate that these nanocomposite catalysts very efficiently convert biomass-derived platform chemicals into cyclic compounds, such as lactones and hydrofurans, with high selectivities and yields.

Direct hydrogenation of biomass-derived butyric acid to n-butanol over a ruthenium-tin bimetallic catalyst.

Catalytic hydrogenation of organic carboxylic acids and their esters, for example, cellulosic ethanol from fermentation of acetic acid and hydrogenation of ethyl acetate is a promising possibility for future biorefinery concepts. A hybrid conversion process based on selective hydrogenation of butyric acid combined with fermentation of glucose has been developed for producing biobutanol. ZnO-supported Ru-Sn bimetallic catalysts exhibits unprecedentedly superior performance in the vapor-phase hydrogenation of biomass-derived butyric acid to n-butanol (>98% yield) for 3500 h without deactivation.

Design of a heterogeneous catalytic process for the continuous and direct synthesis of lactide from lactic acid

We present a continuous one-step reaction pathway for optically pure lactide under atmospheric conditions based on a novel SnO2–SiO2 nanocomposite catalyst. The new heterogeneous catalytic system gave a record high lactide yield of 94% with almost 100% enantioselectivity and long-term stability (>2500 h) from L-lactic acid.

Environmentally benign synthesis of β-hydroxy sulfides using cyclic carbonates catalyzed by large-pore zeolites

Abstract An efficient one-pot synthesis of β-hydroxy sulfides from thiophenol and cyclic carbonates catalyzed by large-pore zeolites has been reported. Reaction of thiophenol with ethylene carbonate in the presence of the Na-X zeolite catalyst gave the highest yield of 2-(phenylthio)ethanol (100%), while reaction with propylene carbonate a highest yield of regioselective product 1-(phenylthio)propan-2-ol was obtained (97%). Enantiomerically pure 1,2-propylene carbonate gave highly regioselective and stereospecific phenylthiopropanol, demonstrating that original chirality of propylene carbonate is retained. A plausible mechanism has been proposed for zeolite-catalyzed transformation involving a chemoselective nucleophilic attack of thiophenoloxide ion onto the less-substituted carbon of cyclic carbonate. The Na-X zeolite catalyst is recyclable and provides advantages of green chemistry approach to the synthesis of β-hydroxy sulfides without the use of any solvent.

An integrated process for the production of 2,5-dihydroxymethylfuran and its polymer from fructose

We report for the first time an integrated process for the selective production of 2,5-dihydroxymethylfuran (DHMF) from fructose via a two-step reaction in 1-butanol (BuOH). Fructose was initially dehydrated to 5-hydroxymethylfurfural in >95% yield using Amberlyst-15, and the resulting solution was directly transformed into DHMF in >97% yield by liquid-phase hydrogenation over a Cu(50)–SiO2 nanocomposite. This nanocomposite catalyst was demonstrated to be highly stable, with no Cu leaching or catalyst deactivation observed. The obtained DHMF/BuOH mixture was then transformed successfully into poly(2,5-furandimethylene succinate) by reaction with succinic acid. Thus, from both environmental and industrial perspectives, this protocol is a novel and effective method for producing a biomass-derived polymer from fructose.