Search results for " carboxylic acid"

Behavior of carbohydrate-based material in black liquor during heating

2004

One industrial softwood Kraft black liquor was heat-treated (at 175 ?C and 190 ?C for 15-60 min) together with laboratory-made soda-AQ (wheat straw and reed canary grass) and Kraft (reed canary grass) black liquors (at 190 ?C for 30 min). The feedstock black liquors were characterized with respect to their polysaccharide (mainly xylem) and aliphatic carboxylic acid contents before and after the heat treatments. It was noted that, due to the higher amount of polysaccharides in the non-wood black liquors (8.2-16.6% of d.s) compared to that in the softwood black liquor (1.4% of d.s), the heat treatment in the former case resulted in a 5-30% increase in the amount of aliphatic acids formed by v…

NonclassicalPschorr andSandmeyer Reactions in Pyrazole Series

2005

The diazonium salt derived from 4-amino-N,1,3-trimethyl-N-(3-methyl-1-phenyl-1H-pyrazol-5-yl)-1H-pyrazole-5-carboxamide (14) was reacted with a mixture of CuSO4 and NaCl, with ascorbic acid as an initiator to afford the planar derivative 4,6-dihydro-1,4,6,8-tetramethyl-3-phenyldipyrazolo[3,4-b:4′,3′-d]pyridin-5(3H)-one (16) and its unexpected isomer 4,6-dihydro-3,4,6,8-tetramethyl-1-phenyldipyrazolo[4,3-b:4′,3′-d]pyridin-5(1H)-one (17), as well as the epimers (3S,4S)- (or (3S,4R)-) and (3S,4R)- (or (3S,4S)-) 4-chloro-2,4-dihydro-1′,3′,5,5′-tetramethyl-2-phenylspiro[pyrazole-3,4′(1′H)-pyrrolo[3,4-c]pyrazol]-6′(5′H)-one (18a and b, respectively). Epimers 18a and b were converted under basic c…

Crystal structure of (E)-pent-2-enoic acid

2015

The molecule of the title compound, C5H8O2, a low-melting α,β-unsaturated carboxylic acid, is essentially planar [maximum displacement = 0.0239 (13) Å]. In the crystal, molecules are linked into centrosymmetric dimersviapairs of O—H...O hydrogen bonds.

effect of the temperature on the electrochemical incineration of organic pollutants

2009

Advanced biorefinery concepts related to non-wood feedstocks

2018

Agricultural residues, such as wheat straw (Triticum aestivum), okra stalk (Abelmoschus esculentus), and giant miscanthus (Miscanthus × giganteus, a hybrid of M. sinensis and M. sacchariflorus) were investigated to assess their possible consumption for integrated lignocellulosic biorefining. The efficient fractionation and recovery of all important chemical components (cellulose, hemicelluloses, and lignin) of such feedstocks are a prerequisite for realistic biorefinery concepts. Water is one of the most eco-friendly solvents with the highest potential for industrial use, and it is also suitable for full-scale biorefinery purposes. For example, under pressure at elevated temperatures over 1…

Electronic and Steric Effects: How Do They Work in Ionic Liquids? The Case of Benzoic Acid Dissociation

2010

The need to have a measure of the strength of some substituted benzoic acids in ionic liquid solution led us to use the protonation equilibrium of sodium p-nitrophenolate as a probe reaction, which was studied by means of spectrophotometric titration at 298 K. In order to evaluate the importance of electronic effect of the substituents present on the aromatic ring, both electron-withdrawing and -donor substituents were taken into account. Furthermore, to have a measure of the importance of the steric effect of the substituents both para- and ortho-substituted benzoic acids were analyzed. The probe reaction was studied in two ionic liquids differing for the ability of the cation to give hydr…

Low-weight carboxylic acids as potential risk factor of compost phytotoxicity

2009

Being intermediates of organic matter degradation, low-weight carboxylic acids (LWCA) can occur at phytotoxic concentrations on bioactive soils or in the processed organic material applied to soil. While toxicity potentials and mixture effects of LWCA are still poorly known, the potential phytotoxicity of the biomaterials is difficult to assess. In the study effective concentrations (EC) of formic, acetic and propionic acids at non adjusted pH were obtained in short-term germination assays (48 h for cress, Lepidium sativum, and 120 h for ryegrass Lolium multiflorum) and subchronic growth assays (21d). Based on the EC values, LWCA inhibited more strongly plant growth than seed germination. I…

Role of low-weight carboxylic acids in phytotoxicity of composts

2013

Combustion behavior of black liquors : droplet swelling and influence of liquor composition

2017

The combustion of black liquor (BL) in a recovery boiler is a central process in a kraft pulp mill for recovering the cooking chemicals and for producing heat and power. This work explored the most important combustion behavior of BL, the swelling of in-flight droplets, from the viewpoint of liquor composition. It also studied the combustion behavior of BL droplets obtained from two biorefining subprocesses (carbonation and hot-water pretreatment, HWP) and sulfur-free pulping alternatives (soda-anthraquinone (AQ) and oxygen-alkali pulping). The formation of a plastic state essential for the swelling of BL droplet was found to result from the melting of an array of carbohydrate-derived aliph…