A Comparison of Dilute Aqueous Isethionic Acid and Sulfuric Acid in Hydrolysis of Three Different Untreated Lignocellulosic Biomass Varieties.

Efficient catalytic hydrolysis of lignocellulosic biomass to sugars is a major challenge in the production of sustainable biofuels and chemical feedstocks. In this study isethionic acid was compared with HSO for hydrolysis of polysaccharides in corn stover, switch grass, and poplar. The catalytic activities of acids were compared by analysis of total reducing sugar (TRS) and glucose yields in a sequence of experiments in water at 90-190 °C using 0.

Hydrolysis and interactions of d-cellobiose with polycarboxylic acids.

The hydrolysis of cellulose model compound d-cellobiose was studied with a series of eight common polycarboxylic acids and two monocarboxylic acids in aqueous medium using 0.500 mmol -COOH/L at 170 °C. The maleic acid showed the highest catalytic activity with turnover frequency (TOF) of 29.

Origin of the Regioselectivity in the Aldol Condensation between Hydroxymethylfurfural and Levulinic Acid: A DFT Investigation.

Our previous work demonstrated that hydroxide ion (OH) was able to catalyze aldol condensation reaction at room temperature between 5-hydroxymethylfurfural (HMF) and levulinic acid (LA). This work identified three primary reaction steps in this condensation reaction using density functional theory (DFT): (1) deprotonation of LA to generate LA ions, (2) LA ions addition at hydroxymethyl site of HMF, and (3) internal dehydration to form the condensation product. The reaction pathway through the C5 of LA forms a linear product that is favored with respect to both energy and configuration in all three elementary reaction steps.

A two step method for the preparation of carbamate cross-linked cellulose films using an ionic liquid and their water retention properties.

Carbamate cross-linked cellulose films can be prepared in a two step method using cellulose dissolved in 1-n-butyl-3-methylimidazolium chloride ionic liquid. The new technique involves casting the film from cellulose ionic liquid solution onto a glass surface and application of alkyl/aryl diisocyanate in dry dimethylsulfoxide solution onto the cellulose - ionic liquid coating on glass and allowing the cross-linking reaction to occur on the pre-formed cellulose coating. The carbamate cross-linked cellulose films formed were characterized by FT-IR, and TG-DTA.

Acidic Ionic Liquids.

Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction.

Interactions of D-cellobiose with selected chloride salts: A ¹³C NMR and FT-IR study.

The interactions of cellulose model compound d-cellobiose with chloride salts of Zn(2+), Ca(2+), Li(+), Sn(2+), La(3+), Mg(2+), K(+) and NH4(+) were evaluated by measuring the (13)C NMR chemical shift changes (Δδ) of the disaccharide due to the addition of salts in D2O. The KCl and NH4Cl showed similar Δδ changes due to interactions only with the Cl(-) anion. Whereas other chloride salts showed interactions with both cation and anion.

Crystal structure of a polymeric calcium levulinate dihydrate: catena-poly[[di-aqua-calcium]-bis-(μ2-4-oxo-butano-ato)].

In the title calcium levulinate complex, [Ca(C5H7O3)2(H2O)2] n , the Ca(2+) ion lies on a twofold rotation axis and is octa-coordinated by two aqua ligands and six O atoms from four symmetry-related carboxyl-ate ligands, giving a distorted square-anti-prismatic coordination stereochemistry [Ca-O bond-length range = 2.355 (1)-2.599 (1) Å].

The effect of metal ions as co-catalysts on acidic ionic liquid catalyzed single-step saccharification of corn stover in water.

The effects of adding Cr(3+), Mn(2+), Fe(3+), Co(2+) Ni(2+), Cu(2+), Zn(2+) and La(3+) chlorides as co-catalysts to 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed saccharification of corn stover in aqueous medium was studied at 140-170 °C, by measuring the total reducing sugar (TRS) and glucose yields. The samples with Mn(2+), Fe(3+), Co(2+) as co-catalysts produced higher TRS yields compared to the sample without the metal ions. The Mn(2+) produced the highest catalytic effect enhancements and produced TRS yields of 68.

Mechanism of 1-(1-propylsulfonic)-3-methylimidazolium chloride catalyzed transformation of D-glucose to 5-hydroxymethylfurfural in DMSO: an NMR study.

The conversion of D-glucose to 5-hydroxymethylfurfural (HMF) in the presence of 5.48 mol% 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyst in DMSO at 150°C was studied using (1)H, (13)C NMR, and visible spectroscopy. The HMF yield rapidly increases in the first 100 min of reaction, however yield drops beyond 100 min and levels off to a maximum yield of about 15.

A comparison of dilute aqueous p-toluenesulfonic and sulfuric acid pretreatments and saccharification of corn stover at moderate temperatures and pressures.

Single step pretreatment-saccharification of corn stover was investigated in aqueous p-toluenesulfonic and sulfuric acid media. Dilute aqueous solution of p-toluenesulfonic acid was a better catalyst than aqueous sulfuric acid of the same H(+) ion concentration for single step pretreatment-saccharification of corn stover at moderate temperatures and pressures. For example, 100mg corn stover heated at 150°C for 1h in 0.

Interactions of D-cellobiose with p-toluenesulfonic acid in aqueous solution: a (13)C NMR study.

The effects of adding D(2)SO(4), and p-toluenesulfonic acid-d to D-cellobiose dissolved in D(2)O were investigated at 23°C by plotting (13)C NMR chemical shift changes (Δδ) against the acid to D-cellobiose molar ratio. (13)C Chemical shifts of all 18 carbon signals from α and β anomers of D-cellobiose showed gradual decreases due to increasing acidity in aqueous D(2)SO(4) medium. The C-1 of the α anomer showed a slightly higher response to increasing D(+) concentration in the surrounding.

Zinc chloride mediated degradation of cellulose at 200 degrees C and identification of the products.

The effect of ZnCl(2) on the degradation of cellulose was studied to develop conditions to produce useful feedstock chemicals directly from cellulosic biomass. Cellulose containing 0.5 mol of ZnCl(2)/mol of glucose unit of cellulose was found to degrade at 200 degrees C when heated for more than 60 s in air.

Mechanism of the dehydration of D-fructose to 5-hydroxymethylfurfural in dimethyl sulfoxide at 150 degrees C: an NMR study.

The anomeric composition of d-fructose in dimethyl sulfoxide changes when the solution is heated from room temperature to 150 degrees C, with a small increase in the alpha-furanose form at the expense of the beta-pyranose tautomer. Additionally, a small amount of alpha-pyranose form was also observed at 150 degrees C. A mechanism is proposed for the dehydration of D-fructose to 5-hydroxymethylfurfural in DMSO at 150 degrees C, where the solvent acts as the catalyst.

Synthesis and solid-state structures of dimethyl 2,2'-bithiophenedicarboxylates.

The syntheses of dimethyl 2,2'-bithiophene-4,4'-dicarboxylate (3), dimethyl 2,2'-bithiophene-3,4'-dicarboxylate (4), and dimethyl 2,2'-bithiophene-3,3'-dicarboxylate (5) are described. Single-crystal X-ray structural analysis of these compounds shows that the thiophene rings in 3 and 4 are nearly coplanar (dihedral angle close to 0 degrees ) and they adopt the anti sulfur conformation in the solid state. Further, the structure of 4 is in agreement with our previous suggestion that there is an electrostatic stabilization of the planar structure due to attraction of the 3-carbonyl oxygen to the sulfur of the distal ring.

Reaction of 1,4-phthalazinedione with furfural: formation of the [5,6]benza-3a,7a-diazaindane system via an unusual skeletal rearrangement.

[reaction: see text] Oxidation of phthalahydrazide (1) with lead tetraacetate in the presence of furfural (3a) in methylene chloride gives [5,6]benza-3a,7a-diaza-3-carboxylindane-4,7-dione-1-ene (7a) in 64% yield. 5-Methylfurfural (3b) also reacted similarly to give the product 7b in 46% yield. Reaction of phathalazine-1,4-dione with thiophene-2-carboxaldehyde gives N-(2-formylthiophene)phthalahydrazide.