Benzene Polycarboxylic Acids Research Articles

A kinetic study of the seeded growth of barium sulfate in the presence of additives

The crystallization of barium sulfate seed crystals in supersaturated solutions has been studied conductometrically and radiochemically at 25°C. After an initial surge reflecting secondary nucleation, the crystal growth follows a rate law second-order in relative supersaturation, both in the absence and presence of additives. Organic polyphosphonates and polymeric molecules such as polygalacturonic acid and ethylenemaleic anhydride co-polymer are effective inhibitors of crystallization. The inhibiting influence of benzene polycarboxylic acids can be related to the tendency for complex formation with barium ions and to the pH of the supersaturated solutions.

Formation of benzene polycarboxylic acids in the oxygen oxidation of solid by-products from coal-conversion processes (CCP) in an alkaline medium

Solid and liquid carbonaceous by-products have been obtained in both coal gasification and liquefaction processes. A study of the oxidation of the solid by-products was undertaken to determine what commercial chemicals could be derived from these materials. The oxygen oxidation of various coal-conversion-process by-products in 10% aqueous sodium hydroxide was investigated at 250 °C and a total pressure of 8.27 MPa (gauge). The products isolated were carbon dioxide and the organic extract, a complex mixture of aliphatic and aromatic acids. The benzene polycarboxylic acids were the major component of the organic extract.

Conformation of the carbonyl groups in benzenepolycarboxylic acids and related compounds

Conformation of the carbonyl groups in benzenepolycarboxylic acids and related compounds

Exhaustive protonation of benzenepolycarboxylic acid polymethyl esters. Polycarbenium ions surrounding a benzene ring

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExhaustive protonation of benzenepolycarboxylic acid polymethyl esters. Polycarbenium ions surrounding a benzene ringDaniel Bruck and Mordecai RabinovitzCite this: J. Am. Chem. Soc. 1976, 98, 6, 1599–1600Publication Date (Print):March 1, 1976Publication History Published online1 May 2002Published inissue 1 March 1976https://doi.org/10.1021/ja00422a063RIGHTS & PERMISSIONSArticle Views40Altmetric-Citations7LEARN 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 (244 KB) Get e-Alerts Get e-Alerts

CHEMISTRY OF HUMIC SUBSTANCES EXTRACTED FROM AN ARCTIC SOIL

A humic and a fulvic acid, extracted from the Ahb horizon of an earth hummock occurring on an Alpine Tundra (Brunic Turbic Cryosol) in the northern part of the Mackenzie river in the Northwest Territories, were characterized by elementary and functional group analyses and by optical measurements. To obtain more detailed structural information, the humic acid, the major organic fraction in the soil extract, was degraded by alkaline permanganate and alkaline cupric oxide oxidation. The degradation products were identified on a gas chromatographic–mass spectrometric–computer system. The analytical characteristics of the Arctic humic and fulvic acids were similar to those reported in the literature for humic and fulvic acids from more moderate climates. However, effects of near-surface permafrost and harsh Arctic climatic conditions manifested themselves in the degradation data. Compared to humic acids from warmer climates, the Arctic humic acid appeared to be poorly developed, exhibiting a low degree of condensation and aromaticity, a low resistance to mild chemical oxidants, yielding only very small amounts of benzenepolycarboxylic acids higher than the di-forms, but relatively large quantities of aliphatic carboxylic acids, especially the n-C16 and n-C18 fatty acids.

The alkaline hydrolysis of humic substances

A humic and a fulvic acid were subjected to four successive hydrolyses with 2 NNaOH solution at 170°C for 3 h. Following each hydrolysis, the degradation products were extracted into ethyl acetate, methylated, separated by chromatographic techniques and identified by mass spectrometry and micro-IR spectrophotometry. One g of humic acid yielded 113.5 mg of aliphatic compounds (mainly n-C 16 and n-C 15) fatty acids), 72.1 mg of phenolics (principally guaiacyl and syringyl derivative) 17.1 mg of benzenepolycarboxylic acid esters and 30.4 mg of N-containing compounds (mainly secondary aromatic amides). Repeated attacks by the alkali on 1.0 g of fulvic acid released 103.8 mg of aliphatics, 133.8 mg of phenolics, 27.0 mg of benzenecarboxylic but 181.8 mg of N-containing compounds. Most of the latter appeared to have been formed during the second, third and fourth hydrolysis which produced reactive compounds that could abstract N from diazomethane which was used as methylating reagent. While 25.0% of the initial humic acid resisted repeated attacks by the alkali, practically all of the fulvic acid was converted into ethyl acetate-soluble products. The alkali-resistant humic acid residue produced high yields of benzenepolycarboxylic acids on alkaline permanganate oxidation. Alkaline hydrolysis, which is known to cleave CO bonds, was found to be relatively specific, although not very efficient, for the degradation of structural phenolic humic and fulvic acid components and for the concomitant liberation of adsorbed aliphatics and N-containing compounds, but was relatively ineffective for degrading aromatic structures linked by CC bonds.

Séparation et dosage par chromatographie liquide sous haute pression des acides benzènepolycarboxyliques : Utilisation de la programmation d'éluant

Separation and determination of benzenepolycarboxylic acids by high-pressure elution liquid chromatography. The use of elution programming The analysis of different benzenepolycarboxylic acids has been carried out on a resin film by high-pressure elution liquid chromatography with Zipax SAX as the support (compressed balls of silica covered with a porous layer containing a strong anionic ion exchanger). The separation of the series of acids from benzoic to benzenehexacarboxylic acid is complete; most isomers are also separated, as well as certain non-acid derivatives. This study has enabled an adequate procedure for programming the elution to be developed, which has enabled the separation of all of the acids considered to be achieved in a single operation. The reproducibility of the operation has been studied. The quantitative analysis of a certain number of these acids has been approached by the method of internal standardization (standardization of response, reproductibility, detection limit).

The Chemical Degradation of a Humic Acid

A humic acid (HA) extracted from the A1 horizon of a Brunizem soil was degraded in the unmethylated and methylated form by sequential reaction with oxidants of increasing strength. The HA was first oxidized with alkaline cupric oxide; the products were then further degraded by oxidation with first alkaline KMnO4 and then with H2O2 in alkaline solution. Unmethylated HA was also degraded by Na-amalgam reduction. The degradation products were extracted into organic solvents, methylated, and separated by preparative gas chromatography into relatively pure components which were analyzed by mass spectrometry and micro-i.r. spectrophotometry. A matching of the mass and i.r. spectra and gas chromatographic retention times of the isolated components with those of authentic specimens led to their identification.The experimental data show that the HA contains a relatively easily degradable portion, which comprises guaiacyl and syringyl units and which may be lignin-derived (about 10% of the total weight). This material is degraded by CuO–NaOH oxidation and Na-amalgam reduction. The bulk of the HA structure, however, consists of a more condensed, chemically complex "core", which degrades on more drastic oxidation into complex phenolic and benzenepolycarboxylic acids. It is likely that the "core" originates in part from condensed lignin and in part from products of microbial synthesis. Of the methods investigated, the CuO–NaOH and the KMnO4 oxidation of methylated HA appear most promising for providing information on the chemical structure of the HA.

Autoxidation in Coal Chemistry and Petroleum Chemistry

The autoxidation reaction of coal was reviewed from the petrochemical point of view. The first step in the oxidation of coal in alkaline aqueous solution is the formation of water insoluble acids by the dissolution of coal and the second step the base-catalyzed autoxidation of water insoluble acids to water soluble aromatic acids such as benzene polycarboxylic acids. At the optimum conditions the yield of water soluble aromatic acids was about 60% from a Japanese bituminous coal, when sodium carbonate was used bleeding carbon dioxide from the reactor. It was confirmed that the side chains of benzene ring, naphthalene nucleus and phenolic compounds were easily decomposed to form benzene carboxylic acids, but anthracene, anthraquinone and diphenyl compounds relatively stable against oxidative decomposition. Properties and utilization of produced aromatic acids along with the application of coal oxidation process were discussed.

Alkaline Permanganate Oxidation of Methylated and Unmethylated Fulvic Acid

AbstractThe alkaline permanganate oxidation of humic and fulvic acids yields small amounts of benzene polycarboxylic acids that range from the di‐ to the hexa‐form. Low yields may be due to the presence of electron‐donating substituents, such as OH groups, on aromatic rings. To make the rings less susceptible to destruction by alkaline KMnO4, we attempted to reduce the electron‐donating effect by converting OH groups via methylation to OCH3 groups. The alkaline permanganate oxidation of methylated FA, however, yielded the same types and similar amounts of benzene carboxylic acids as that of the untreated FA. Failure of methylation to increase the variety and yield of oxidation products may be due to inability to either methylate all (phenolic) OH groups or, more likely, to reduce electron‐donating effects sufficiently.

Recent Progress on the Autoxidation of Petroleum Hydrocarbons and Polycyclic Hydrocarbons

Recent progress on the autoxidation of petroleum hydrocarbons and of polycyclic hydrocarbons along with coal was reviewed. Initiation reation by intiators or metal salts is affected by reaction conditions. Propagation reaction depends on the carbon-hydrogen bond dissociation energy but not so much on peroxy radicals. The rate of propagation step is varied with the dielectric constant and water content of the solution, and is increased remarkably by cobalt bromide. Inhibition of autoxidation by phenolic or amine compounds involves the hydrogen abstraction step.The electron releasing substituents on phenols increase the inhibition effect and a synergistic effect may be obtained in the presence of hindered and non-hindered phenols. Polycyclic aromatic hydrocarbon inhibits the autoxidation, but its oxidation proceeds relatively easily in the basic solution. Oxidation of bituminous coal in alkaline aqueous solution under pressure results in the formation of benzene polycarboxylic acids.

Transcarboxylation reactions of potassium benzoate and of potassium salts of benzenepolycarboxylic acids

Transcarboxylation reactions of potassium benzoate and of potassium salts of benzenepolycarboxylic acids

Low-Pressure Hydrogenation of Some Benzenepolycarboxylic Acids with Rhodium Catalyst

Low-Pressure Hydrogenation of Some Benzenepolycarboxylic Acids with Rhodium Catalyst

Studies on the Synthesis and Application of Organic Acids. III

The synthesis of benzene-polycarboxylic acids of growing demand for theproduction of synthetic fiber and plastics has been investigated using m-xylene as a starting compound. The present study has been directed to establish the synthesis conditions and yields for mesitylene (2) and isodurene (3) through the Friedel-Crafts reaction of m-xylene (1); 4-chloromethyl-m-xylene (4) and 4, 6-dichloromethylm-xylene (5) through chloromethylation of (1); and 2-chloromethylmesitylene (6) and 2, 4-dichloromethylmesitylene (7) through chloromethylation of (2). Trimesic acid, trimellitic acid, pyromellitic acid, prehnitic acid, and benzenepentacarboxylic acid were obtained via potassium permanganate oxidation of (2), (4), (5), (6), and (7), respectively, and the effects of the reaction time on the yields have also been studied.

Wet Combustion of Organic Substances with Iodic Acid. V. Total Oxidation of Benzene Polycarboxylic Acids

Wet Combustion of Organic Substances with Iodic Acid. V. Total Oxidation of Benzene Polycarboxylic Acids

Researches on the chemistry of coal-Part IV. The oxidation of the residue from the benzene-pressure-extraction process

Since publishing the last paper of this series, in which was described our process of extracting coals with benzene under pressure up to 700 lb. per square inch, and of fractionating the crude extracts thereby obtained, we have turned our attention to the “residues” resulting from it, which in the case of most bituminous coals usually form about 90 per cent, of the actual coal substance. And in this paper the results of our experiments during the past eighteen months upon their oxidation by means of an alkaline solution of potassium permanganate are briefly described. It was decided to publish these results a t this stage of the investigation because of the recent publication by Mr. W. Francis and Prof. R. Y. Wheeler of an account of their work upon “The Properties and Constitution of Coal Ulmins,” in the course of which they oxidised, with either hydrogen peroxide or 30 per cent, nitric acid, what they termed the “regenerated ulminsfrom coals,” obtaining good yields of oxalic and succinic acids together with small quantities of other acids, among which picric acid, and certain benzene polycarboxylic acids were mentioned. They state ( loc . cit ., p. 2245) “symmetrical benzene tetracarboxylic acid (m. p. 264° with decomposition) has been isolated in a pure form by slow crystallisation from acetic acid, and its methyl ester (m. p. 138°) formed. The tricarboxylic acid appears to be trimellitic acid, but it has not yet been obtained in a sufficiently pure crystalline form to identify.” No ultimate analyses of these acids were, however, published.