Aqueous Mineral Acid Solutions Research Articles

The extraction of trace amounts of gold from different aqueous mineral acid solutions by diphenyl-2-pyridylmethane dissolved in chloroform

Diphenyl-2-pyridylmethane, a high molecular weight substituted pyridine has been examined and found to be a useful solvent extraction reagent. Its behaviour is similar to amines in that it forms salts with mineral acids. The acid ionization constant (pKBH+) determined spectrophotometrically has a value of 4.41±0.06 at 25 °C. A study of the partition behaviour of trace amounts of gold between mineral acid solutions and 0.1M diphenyl-2-pyridylmethane dissolved in chloroform indicates that the metal can be quantitatively extracted from dilute mineral acid solutions and also from concentrated hydrochloric acid media in a single extraction. Attempts have been made to gain an understanding of factors affecting the extraction of gold. Common anions have little effect on extraction in concentrations upto 1M. Separation factors of a number of metal ions relative to gold are reported for three mineral acid systems; and gold has been estimated in some synthetic samples using neutron activation technique by prior extraction with 0.1M solution of diphenyl-2-pyridylmethane dissolved in chloroform.

Solvation of thiocyanate complexes of mercury(II) by 2-hexylpyridine from aqueous mineral acid solutions

The extraction of trace amounts of mercury(II) by 2-hexylpyridine dissolved in benzene from aqueous mineral acid solutions has been studied. The replacement of chloride, nitrate and sulfate ions by the potentially ambidentate, linear and less basic thiocyanate group offers interestingly high extraction coefficients. The value of the distribution coefficients may be lowered by complexing mercury with oxalate, thiosulfate, acetate or citrate ions in the aqueous phase. The possible mechanism of extraction has been discussed in the light of the results of extraction isotherms and slope analysis data. Distribution coefficients and separation factors of several metal ions relative to mercury(II) are reported for the three mineral acid systems and the possible removal of mercury along with some other inorganic pollutants from aqueous solutions is suggested.

Mesoionic compounds. Part 5. The acid-catalysed hydrolysis of diarylisosydnones

The acid-catalysed hydrolyses and protonation behaviour of some 4-(para-substituted phenyl)-5-phenylisosydnones have been studied in aqueous solutions of mineral acids. For perchloric and sulphuric acid, plots of the first-order rate coefficients k1 against [H+] show maxima which arise from extensive protonation of the substrates. Analyses of the kinetic data by Bunnett and Bunnett–Olsen criteria are consistent with a bimolecular mechanism. Oxygen-18 tracer studies establish that the acid-catalysed hydrolyses of diarylisosydnones proceed through two different pathways involving attack of water at both the C-5 and the C-2 carbonyl carbon atom.

Solvation of cobalt-thiocyanate complexes by 2-hexylpyridine from aqueous mineral acid solutions

A study of the distribution of cobalt between mineral acid solutions containing potassium thiocyanate and 0.1M 2-hexylpyridine in benzene has been undertaken. Cobalt can be quantitatively extracted as its thiocyanate complex from very dilute acid solutions containing 0.1–1M KSCN. Variation of the distribution coefficient DCo in terms of the ligand concentration in the organic phase has allowed the formula of the extracted species to be determined as Co(HPy)4 (SCN)2. The effects of oxalate, acetate, fluoride, ascorbate, sulphate and thiosulphate ions on the extraction of cobalt from three mineral acid solutions have been reported. The extraction coefficients of several elements are given for the 0.1M 2-hexylpyridine in three systems containing 0.5M KSCN with 0.25M HNO3, 0.05M HCl and 0.05M H2SO4 respectively; and their factors for separation from cobalt are estimated.

Macrokinetic features of the degradation of polyoxymethylene blocks in aqueous solutions of mineral acids

A kinetic study has been made of the acid catalyzed degradation of polyoxymethylene blocks in aqueous solutions of H 2SO 4, HCl and H 3PO 4. The effective degradation rate constant is a function of macrokinetic parameters, i.e. roughness on the surface of blocks, and the depth of the reaction zone. A relationship has been found between processes of degradation of polymeric blocks and corresponding changes in mechanical properties.

Mesoionic compounds. Part IV. Acid catalysed hydrolysis and protonation behaviour of 4,5-diarylisosydnones

The acid catalysed hydrolyses of some 5-(para-substituted phenyl)-4-phenylisosydnones have been studied in aqueous solutions of mineral acids over a wide range of acidities. For perchloric and sulphuric acids plots of the first-order rate coefficients k1 against [H+] show maxima which are caused by extensive protonation of the substrate. Analysis of these data by Bunnett and Bunnett–Olsen criteria, solvent deuterium isotope effects, and substituent effects are consistent with an A-2 mechanism.

Aromatic protonation. XI. Catalysis by undissociated acids in concentrated aqueous mineral acid solutions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAromatic protonation. XI. Catalysis by undissociated acids in concentrated aqueous mineral acid solutionsA. J. Kresge, S. G. Mylonakis, and L. E. HakkaCite this: J. Am. Chem. Soc. 1972, 94, 12, 4197–4199Publication Date (Print):June 1, 1972Publication History Published online1 May 2002Published inissue 1 June 1972https://doi.org/10.1021/ja00767a026RIGHTS & PERMISSIONSArticle Views37Altmetric-Citations6LEARN 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 (331 KB) Get e-Alerts Get e-Alerts

Reactions of cycloammonium cations

Only an indole trimer can be isolated from the reaction of indole with pyridine, quinoline, and isoquinoline in aqueous solutions of mineral acids. In anhydrous media the hydrochlorides of these heterocycles electrophilically attack the 3 position of the indole ring to form low yields of 3-hetarylindoles. Indole reacts with acridine, even in aqueous media, under the influence of protonating agents and is converted to 9-(3-indolyl)acridine and acridine in good yields. The acridinylation of indole and 1- and 2-alkyl- or phenylindoles in the presence of acylating agents proceeds similarly.

Solvent extraction of Hf(IV) and Zr(IV) with some 1-phenyl-3-methyl-4-acylpyrazolones-5

The distribution of Hf, Zr and Nb between aqueous solutions of mineral acids and solutions of 1-phenyl-3-methyl-4-acylpyrazolones-5 (acyl=acetyl, ethoxycarbonyl, butyryl, capronyl, capryl and benzoyl) in various organic solvents has been studied. The dependence of the distribution ratio of metal on the acidity of the aqueous phase, the analytical concentrations of reagents and metals, and on the organic solvent was investigated. The composition of the complex extracted is MeP4 for Hf and Zr. The conditions for the separation of Zr, Hf and Nb are defined, and a comparison is made with extractions by means of thenoyltrifluoroacetone.

Separation of primary aromatic amines on alginic acid and carboxymethylcellulose columns

The chromatographic behavior of primary aromatic amines in columns of algina acid and carboxymerthylcellulose was investigated extensively. Aqueous solutions of mineral acids and organic acids, water and aqueous—organic solvents were used as eluents. The relation between the data obtained on a thin layer and those obtained in a column was examined.

Water Content of Bis(2-Chloroethyl) Ether in Equilibrium at 25° C. with Aqueous Mineral Acid Solutions.

Water Content of Bis(2-Chloroethyl) Ether in Equilibrium at 25° C. with Aqueous Mineral Acid Solutions.

33. The solvent-extraction of beryllium from aqueous solutions of mineral acids by alkyl esters of phosphoric acid

33. The solvent-extraction of beryllium from aqueous solutions of mineral acids by alkyl esters of phosphoric acid

520. The dissolution of beryllium in aqueous solutions of mineral acids and ammonium fluoride

The rates of dissolution of beryllium metal in aqueous solutions of nitric sulfuric hydrochloric and hydrofluoric acid, and of ammonium fiuoride, were measured, and the relative rates for equimolar concentrations of the acids under similar conditions were found to be HF > H/sub 2/SO/sub 4/ approx equal HCl> HNO/sub 3/. The rate varies with the source and method of fabrication of the metal. Dissolution of beryllium in nitric acid was examined in detail as a function of acid concentration, temperature, surface properties of the metal, and the presence of hydrofluoric acid. (auth)

The determination of the solubility of organic solvents in mineral acids

A knowledge of the solubility of organic solvents in aqueous solutions of mineral acids is shown to be important in solvent extraction studies. The method described depends upon the direct measurement of the amount of solvent thrown out of the aqueous phase on neutralization. The results of experiments on the solubility of iso-propyl ether in aqueous hydrochloric acid are given. The accuracy, limitations, and uses of the method are discussed.

INFRARED SPECTRUM OF THE H3O+ ION IN AQUEOUS SOLUTIONS

The absorption spectra at 25 °C. of aqueous solutions of mineral acids (HCl, HBr, HNO3, HClO4, H2SO4, H3PO4) and of some of their acid salts in various concentrations were measured in the infrared from 2 to 25 µ. In all cases three broad bands were present at 1205, 1750, and 2900 cm.−1 arising from the H3O+ ion. Cooling the samples, and even supercooling them down to liquid air temperature, produced no major changes in the spectra. The bands of the D3O+ ion were also found at 960, 1400, and 2170 cm.−1 in solutions of DCl in heavy water. Thus, the existence of discrete hydronium ions in the liquid state, with average life longer than 10−13 second, is confirmed. Infrared spectra provide a means of estimating the extent of ionization of strong acids in solution.