Catalytic amounts of Brønsted acidic ionic liquids promoted esterification: Study of acidity–activity relationship

The dehydration of D‐fructose and glucose has been studied with acidic ionic liquids as catalysts. A series of Brønsted‐acidic ionic liquids has been synthesized and tested in the dehydration of D‐fructose. The results showed that N‐methyl‐2‐pyrrolidonium methyl sulfonate [NMP]+[CH3SO3]− and N‐methyl‐2‐pyrrolidonium hydrogen sulfate [NMP]+[HSO4]− have high catalytic activity. Highly efficient and selective dehydration of D‐fructose to 5‐hydroxymethylfurfural (HMF) was achieved in dimethyl sulfoxide (DMSO) under mild conditions. For example, a 72.3 % yield of HMF with 87.2 % selectivity were obtained for 2 h at 90 °C in the presence of 7.5 mol % [NMP]+[CH3SO3]−. The effects of the reaction temperature, time, and solvent were investigated in detail. The catalyst and solvent can be recycled for the dehydration of D‐fructose. The Hammett method was used to determine the acidities of these ionic liquids, which indicated that the acidity and molecular structure have strong effects on the catalytic activity of ionic liquids. Based on the experimental results, a possible reaction mechanism for the dehydration of D‐fructose is proposed.

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“…[29][30][31] The detailed synthesis conditions are described in the experimental section. [ À is a white solid at room temperature.…”

Section: Resultsmentioning

confidence: 99%

Efficient and Selective Dehydration of Fructose to 5‐Hydroxymethylfurfural Catalyzed by Brønsted‐Acidic Ionic Liquids

2010

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“…[30][31][32] The catalytic behavior of RTILs in the organic reactions, for instance, the yield of the product, depends on the acid-base properties of RTILs. [33][34][35][36][37] In order to clarify solvent natures, one must have extensive knowledge of physicochemical and Brønsted and/or Lewis acid-base properties of ionic liquids. Experimental results for the physicochemical properties [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] and solvatochromic parameters [53][54][55] of ionic liquids with the hydroxyl groups have been reported.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical and Acid-base Properties of a Series of 2-Hydroxyethylammonium-based Protic Ionic Liquids

et al. 2012

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“…The acidity strength of an acid can be expressed by Hammett function using UV-visible spectrophotometry. For example, the acidity measurement of nonchloroaluminate ILs had been performed successfully utilizing UV-visible spectroscopy with Hammett indicator method [20], and this method was applied to determine the acidity of protic pyridinium ILs, Brønsted acidic ILs, and the strength of carboxylic acids in different ILs [21][22][23][24].…”

Section: Acidity Determination Of the Ilsmentioning

confidence: 99%

Caprolactam-Based Brønsted Acidic Ionic Liquids for Biodiesel Production from Jatropha Oil

et al. 2017

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Abstract:Caprolactam-based ionic liquids show many advantages, such as the lower toxicity, lower cost, and a simple preparation process. In this work, caprolactam-based ionic liquids were prepared and adopted as catalysts for the transesterification of Jatropha oil with methanol. The results demonstrated that the SO 3 H-functional caprolactam-based ionic liquids have higher catalytic activity than those of the caprolactam-based ionic liquids without sulfonic group or the SO 3 H-functional pyridine -based ionic liquids, attributed to their stronger Brønsted acidity. By optimizing the reaction parameter, the biodiesel yield catalyzed by 1-(4-sulfonic group) butylcaprolactamium hydrogen sulfate ([HSO 3 -bCPL][HSO 4 ]) could reach above 95% at 140 • C for 3 h. Furthermore, the ionic liquid had a good reusability.

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Catalytic amounts of Brønsted acidic ionic liquids promoted esterification: Study of acidity–activity relationship

Cited by 157 publications

References 23 publications

Efficient and Selective Dehydration of Fructose to 5‐Hydroxymethylfurfural Catalyzed by Brønsted‐Acidic Ionic Liquids

Efficient and Selective Dehydration of Fructose to 5‐Hydroxymethylfurfural Catalyzed by Brønsted‐Acidic Ionic Liquids

Physicochemical and Acid-base Properties of a Series of 2-Hydroxyethylammonium-based Protic Ionic Liquids

Caprolactam-Based Brønsted Acidic Ionic Liquids for Biodiesel Production from Jatropha Oil

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