Improved Production of 5-Hydroxymethylfurfural in Acidic Deep Eutectic Solvents Using Microwave-Assisted Reactions.

Eduarda S Morais,Carmen S R Freire,Armando J D Silvestre,Mara G Freire

doi:10.3390/ijms23041959

Eduarda S Morais, Carmen S R Freire + Show 2 more

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https://doi.org/10.3390/ijms23041959

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Abstract

Hydroxymethylfurfural (5-HMF) is a key platform chemical, essential for the production of other chemicals, as well as fuels. Despite its importance, the production methods applied so far still lack in sustainability. In this work, acidic deep eutectic solvents (DES), acting both as solvent and catalyst, were studied for the conversion of fructose into 5-HMF using microwave-assisted reactions. These solvents were screened and optimized by varying the hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA). The bio-based solvent γ-valerolactone (GVL) was also applied as additive, leading to a boost in 5-HMF yield. Then, a response surface methodology was applied to further optimize operating conditions, such as reaction time, temperature and wt.% of added GVL. The highest 5-HMF yield attained, after optimization, was 82.4% at 130 °C, in 4 min of reaction time and with the addition of 10 wt.% of GVL. Moreover, a process for 5-HMF recovery and DES reuse was developed through the use of the bio-based solvent 2-methyltetrahydrofuran (2-Me-THF), allowing at least three cycles of 5-HMF production with minimal yield losses, while maintaining the purity of the isolated 5-HMF and the efficacy of the reaction media.

Highlights

The instability of the hydrocarbons market as well as the rising concerns about global warming and the diminishing of fossil resources has led to a paradigm shift from a fossil to a bio-based economy [1]
([N1111 ]Cl) as hydrogen bond acceptor (HBA) and citric (CA), lactic (LA), glycolic (GA), malic (MA) and levulinic (Lev) acids as hydrogen bond donor (HBD) were prepared in a 1:1 molar ratio, when possible, with the exception of the deep eutectic solvents (DES) based in glycolic acid since no DES formation was observed for ([N1111 ]Cl:GA)
([N1111]Cl) as HBAs and citric (CA), lactic (LA), glycolic (GA), malic (MA) and (Lev) acids as HBDs were prepared in a 1:1 molar ratio, when possible, with the exception of the DES based in glycolic acid since no DES formation was observed for ([N1111]Cl:GA)

Summary

Introduction

The instability of the hydrocarbons market as well as the rising concerns about global warming and the diminishing of fossil resources has led to a paradigm shift from a fossil to a bio-based economy [1]. Biomass is an abundant and renewable feedstock to be applied in this context It is mainly composed of carbohydrates, which can be isolated and converted into a plethora of chemicals, materials and fuels. Among the compounds derived from carbohydrates, furans are considered to have a high potential for the production of chemicals, materials and fuels [6] Furans, such as furfural, 5-hydroxymethylfurfural (5-HMF) and 2,5-furandicarboxylic acid have been considered by the U.S Department of Energy (DOE) amongst the key chemicals attained from biomass sources [7]. This compound is a versatile intermediate that can be converted into 2,5-furandicarboxylic acid, 2,5-dihydroxymethylfuran and

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