Eco-Friendly Synthesis of 5-Hydroxymethylfurfural and Its Applications as a Starting Material to Synthesize Valuable Heterocyclic Compounds

Abstract

The development of new catalysts for converting biomass to high-value chemicals has received much attention for both energy and the environment; thus, designing and developing green and efficient catalysts for biomass conversion is pertinent. In this study, we developed a novel homogeneous catalyst in an ecosustainable reaction medium of ionic liquids (ILs) to convert carbohydrates to 5-hydroxymethylfurfural (HMF), a renewable building block for biodiesel and other valuable compounds, using experimental and computational tools. Particularly, based on 1,4diazabicyclo[2.2.2]octane, the synthesized IL, which bears Brønsted acid sites, in combination with 1-ethyl-3-methylimidazolium chloride (or [EMIM]Cl) as a binary IL catalyst/solvent was investigated for the conversion of carbohydrates (i.e., fructose, glucose, sucrose, and cellulose) to HMF. The results reveal that the reaction occurs under simple and mild conditions, in which fructose can be converted with a high yield, even at room temperature. Importantly, the product, HMF, can be easily isolated using liquid−liquid extraction that overcomes the HMF separation challenge posed by using fractional distillation. Last but not the least is that the catalyst with structural integrity can be effectively recovered and reused with a slight decrease in catalytic activity. In addition to the investigation of the operation parameters, the detailed reaction mechanism of the conversion of fructose to HMF was revealed by electronic structure and statistical mechanic calculations. Moreover, the as-prepared HMF can also be converted to high-value heterocyclic compounds such as (5-(di(1H-indol-3-yl)methyl)furan-2-yl)methanol, (5-(3-phenyl-1-(piperidin-1-yl)prop-2-yn-1yl)furan-2-yl)methanol, ethyl 4-(5-(hydroxymethyl)furan-2-yl)-2-methyl-1,4-dihydrobenzo [4,5]imidazo[1,2-a]pyrimidine-3-carboxylate, and 2-amino-4-(5-(hydroxymethyl)furan-2-yl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile using deep eutectic solvents as reaction media. Therefore, with the novel activities and high sustainability, the designed catalytic system has shown great potential for industrial applications of converting carbohydrates to value-added products.

Conversion of cellulose into valuable chemicals using sulfonated amorphous carbon in 1-ethyl-3-methylimidazolium chloride

“…Research on the transformation of available carbohydrates into valuable chemicals has received much attention over the past decade. [1][2][3][4][5] The transformation of cellulose based on agricultural residues into useful chemicals has been studied extensively for practical applications. [6][7][8] Facing the shortage of fossil fuels and uctuating prices of gasoline, the development of clean, safe, and sustainable alternative energy sources has become an urgent mission.…”

Efficient Synthesis of Novel Biginelli and Hantzsch Products Sourced from Biorenewable Furfurals Using Gluconic Acid Aqueous Solution as the Green Organocatalyst

“…11−13 FF and HMF are often used as representative furanic molecules to demonstrate the diverse substrate scope of various synthetic methodologies, such as the synthesis of heterocycles. 14 However, the systematic study of carbohydratederived 5-substituted-2-furaldehydes as substrates for synthesizing various classes of heterocyclic molecules is underexplored. 15 Such systematic studies will assist in unraveling the much-desired reactivity patterns of these biorenewable molecules and expanding the horizon of their derivative chemistry.…”

“…In the second step, the reactive intermediates are synthetically transformed into products of desired structural features. , In this regard, the acid-catalyzed dehydration of pentoses (e.g., xylose) leads to furfural (FF, 1a ), whereas the dehydration of hexoses (e.g., glucose) forms 5-(hydroxymethyl)­furfural (HMF, 1e ). , The processes typically use an acid catalyst of some sort and produce water as an innocuous byproduct. The production and derivative chemistry of FF and HMF have been explored scrupulously over the past decades. , In this regard, the synthesis and study of heterocycles is one of the cornerstones of synthetic organic chemistry primarily due to the remarkable properties and fascinating pharmacological activities of the heterocyclic molecules. − Significant importance has been given to designing green synthetic protocols for various heterocyclic moieties. − FF and HMF are often used as representative furanic molecules to demonstrate the diverse substrate scope of various synthetic methodologies, such as the synthesis of heterocycles . However, the systematic study of carbohydrate-derived 5-substituted-2-furaldehydes as substrates for synthesizing various classes of heterocyclic molecules is underexplored .…”

An efficient and practical approach for the continuous‐flow synthesis of 5‐hydroxymethylfurfural from carbohydrates using an acidic ionic liquid

“…21,22 In recent years, the use of ILs as media for fructose dehydration has attracted increased attention as a result of the growing concern over damage to the environment. [23][24][25][26][27][28][29][30][31][32][33][34] Zhao and coworkers studied IL generated by 1-ethyl-3-methylimidazolium chloride with metal salts for converting 5-HMF from glucose. The highest efficiency was 70% at 80 °C for 3 h using CrCl 2 .…”