Aqueous Solutions Of Organic Acids Research Articles

Determination of limiting molar conductivities of weak organic acids in aqueous solutions

Conductance, potentiometric, and spectrophotometric measurements have been made at 25°C of aqueous solution containing sulfanilic, hippuric, mandelic, and 3,5-dinitrosalicylic acids at different concentrations. Conductance data were analyzed using the methods of Fuoss-Kraus, Kraus-Parker, and Shedlovsky for conductivity of the free ions. Using the calculated limiting conductances, activity coefficients, and degrees of dissociation, the dissociation constants of the weak acids were determined. From plots Δ vs c1/2, reliable values for Δ0 were estimated, using a computer program, and by means of an iterative method the proper value of Δ0 was determined, independently of that initially introduced. Values of pK were also obtained from potentiometric and spectrophotometric measurements. Evidence for the existence of univalent and divalent ions in aqueous solutions of 3,5-dinitrosalicylic acid was obtained spectrophotometrically, this fact justifying the poorer results provided by conductance measurements.

The dissolution of quartz in dilute aqueous solutions of organic acids at 25°C

The dissolution of quartz in dilute aqueous solutions of organic acids at 25° and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 μmole/Kg compared to 50 μmole/Kg in water and a 20 mmole/Kg solution of acetate at pH 7. Solutions of salicylic, oxalic, and humic acids also accelerated the dissolution of quartz in aqueous solution at pH 7. The rate of dissolution in organic acids decreased sharply with decreasing pH. The possibility of a silica-organic acid complex was investigated using UV-difference spectroscopy. Results suggest that dissolved silica is complexed by citrate, oxalate and pyruvate at pH 7 by an electron-donor acceptor complex, whereas no complexation occurs between silica and acetate, lactate, malonate, or succinate. Three models are proposed for the solution and surface complexation of silica by organic acid anions which result in the accelerated dissolution and increased solubility of quartz in organic rich water.

Extraction conditions of organic acids in aqueous solution

Extraction conditions of organic acids in aqueous solution

A method for the determination of volatile organic acids in aqueous solutions and urine, and the results obtained in propionic acidaemia, β-methylcrotonylglycinuria and methylmalonic aciduria

A rapid and simple method for the determination of the volatile acidic and neutral substances in aqueous solutions and urine is described and evaluated. The results obtained in the analysis of urine from normal humans and patients with propionic acidaemia, β-methylcrotonylglycinuria and methylmalonic aciduria are presented and discussed.

Complex of palladium with p-benzoquinone

1. In the interaction of olefins (ethylene, propylene) with aqueous-organic acid solutions of PdSO4 and p-benzoquinone, a complex with the composition (p-C6H4O2)Pd2SO4·3H2O was obtained. 2. The IR spectrum, x-ray LIII absorption spectrum, and chemical properties of the complex were discussed, and a hypothesis on its structure was advanced.

Proton transfer in some model equilibria studied by the ultrasonic method

The rate constants in the equilibria involving proton transfer between heterocyclic amines and water and also some amines and organic acids in aqueous solution have been studied using the ultrasonic relaxation method. The dynamics of proton transfer do not appear to depend on the conformational properties of the amines. The well established relationship between the rate constants and the difference in pK between the proton acceptor and donor molecule are obeyed. Other aspects studied include the determination of the activation energy of a diffusion controlled step in one of the equilibria and the isotope effect. Finally attempts were made to calculate some of the rate constants.

Ionization constants for very weak organic acids in aqueous solution and apparent ionization constants for water in aqueous organic mixtures

A potentiometric method using a glass electrode has been applied to determination of apparent ionization constants for water in binary mixtures of water with tetrahydrofuran, methanol, 1,3-propanediol, glycerol, sucrose, and glucose at 25°C. Further calculations with these apparent ionization constants, which are now based explicitly on the previously implicit assumption that ionization of the organic component is negligible compared to ionization of water, permit evaluation of ionization constants for several very weak acids in purely aqueous solvent. Resulting pK values derived from this work and from our earlier work are as follows: glucose (12.38), sucrose (12.75 and 12.80), glycerol (14.05 and 14.07), ethylene glycol (14.44 and 14.52), methanol (15.2), 1,3-propanediol (14.8 and 15.0), 1-propanol (15.1), 2-propanol (15.7), and 2-methyl-2-propanol (15.0).

Biogenetic-type syntheses of isoprenoid and diisoprenoid derivatives of orcinol

The products formed by condensation of orcinol with 2-methyl-3-buten-2-ol, with geraniol, and with linaloöl in aqueous solutions of organic acids have been separated and identified. C-isoprenyl- and C-geranyl-orcinols are obtained as major products. Minor amounts of the corresponding hydrates, chromans, chroman hydrates, and hexahydroxanthene derivatives are also formed.

The quantitative extraction and gas-liquid chromatographic determination of organic acids in urine.

A method for the quantitative extraction and gas-liquid chromatographic determination of organic acids in aqueous solution and biological fluids has been developed. The acids are extracted by a DEAE-Sephadex anion-exchange column, neutral and basic compounds are removed by washing with water and the acids are eluted with a pyridinium acetate buffer. The ethoximes of oxo-acids are formed in the eluate to stabilise these compounds and the eluate is then freeze-dried under carefully controlled conditions. The residue of dry free acids and their pyridinium salts is trimethylsilylated and the trimethylsilyl derivatives are separated and quantitatively determined by gas-liquid chromatography with the use of internal standards. The method would not be suitable for the determination of formic, acetic, propionic or butyric acid because of their volatility.The accuracy and precision of the method, which can be applied to other protein-free biological fluids as well as urine, are discussed.

Mechanisms of Browning Degradation ofd-Fructose in Special Comparison withd-Glucose-Glycine Reaction

Degradation mechanisms of d-fructose by the interaction with amino acids or organic acids in aqueous solution at initial pH 5.5 heated at 100°C were investigated and a substantial difference in mechanisms between fructose degradation and glucose-glycine reaction was presented. d-Fructose browned more intensely than did d-glucose in lower concentration of glycine and/or in earier stage of reaction period. By catalytic action of carboxylate anions without any condensation with amino groups, d-fructose was decomposed to 3-deoxy-d-erythrohexosulose, 5-(hydroxymelhyl)-2-furaldehyde, and a less amount of pyruval-dehyde through caramelization. It was considered that the main path of fructose degradation was 1,2-enolization but 2,3-enolization would also occur to a little extent.

Analysis of aqueous solutions of organic acids by pyrolysis of their tetramethylammonium salts in the gas chromatograph

Analysis of aqueous solutions of organic acids by pyrolysis of their tetramethylammonium salts in the gas chromatograph

Production of Dislocation Etch Pits on Calcite using Optically Active Etchants

SEVERAL etchants, usually consisting of aqueous solutions of organic acids, have been shown1–5 to produce etch pits at the points of emergence of dislocations on the rhombohedral cleavage faces of calcite crystals. Moreover, if the pits are particularly well defined it is often possible to deduce, from their internal structure, the plane and the direction in which the dislocation line runs through the crystal, a possibility of considerable interest to us since we are endeavouring to assess the role of line imperfections in the chemical reactivity of calcite.

Complexation of Organic Acids and Bases with Their Salts in Aqueous Solution

The solubilization of certain organic acids in aqueous solutions of their salts has been attributed to a complexation between the acid and anion species. In the present investigation solubility studies were used in an effort to ascertain the factors influencing such complexation and to determine the nature of the complexes formed. Benzoic acid, salicylic acid, p-hydroxy-, 2,4-dihydroxy-, 2,5-dihydroxy-, 2,6-dihy- droxy-, and 3,4-dihydroxybenzoic acids, phenylacetic acid, adipic acid, barbituric acid, barbital, phenobarbital, and saccharin showed substantial increases in solubility in the presence of their sodium salts. Studies with atropine and procaine in solutions of their salts showed that similar complexes occurred in these systems. In some cases insoluble complexes were formed at high salt concentrations. Addition of hydroxyl groups to benzoic acid favors complexation. Quantitative evaluation of equilibrium constants could not be determined because of a concurrent salting out effect.

Disssociation constants of organic acids in aqueous solution

Abstract

Small Panel Taste Testing of Wine

Absolute and difference thresholds were determined for ethyl alcohol, dextrose, levulose, glycerol, tannin, ethyl acetate, acetaldehyde, sulfur dioxide and various nonvolatile organic acids in aqueous solution and in wine. Difference thresholds were found to be higher in wine. The paired comparison was found to be more sensitive than the triangular design. Fatigue and sensory carry-over was found in tannin determinations. The panel showed improved performance on repeated tastings of sucrose solutions, using a red table wine as test medium. Other sub[unknown] stances tested showed no differences on protracted tastings.

Infrared Absorption of Aqueous Solutions of Organic Acids and Their Salts

Infrared Absorption of Aqueous Solutions of Organic Acids and Their Salts

VII.The limiting conductivities of organic acids in aqueous solutions

VII.The limiting conductivities of organic acids in aqueous solutions

Electrokinetics. XVIII. Interfacial Energy and the Molecular Structure of Organic Compounds. IV. The Electrokinetic Behavior of Charcoals in Aqueous Solutions of Organic Acids

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrokinetics. XVIII. Interfacial Energy and the Molecular Structure of Organic Compounds. IV. The Electrokinetic Behavior of Charcoals in Aqueous Solutions of Organic AcidsVernon L. Frampton and Ross Aiken. GortnerCite this: J. Phys. Chem. 1937, 41, 4, 567–582Publication Date (Print):April 1, 1937Publication History Published online1 May 2002Published inissue 1 April 1937https://doi.org/10.1021/j150382a007RIGHTS & PERMISSIONSArticle Views22Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (746 KB) Get e-Alerts