L. G. Chekanova

Determination of hydrazides and 1,2-diacylhydrazines of aliphatic carboxylic acids by conductometric titration

A procedure is developed for the conductometric titration of hydrazides and 1,2-diacylhydrazines of aliphatic carboxylic acids with HCl or KOH in nonaqueous and water-alcohol solutions. The procedure is suitable for the determination of the major substance in hydrazides of C5H11-C12H25 aliphatic carboxylic acids and CH3-C7H15 1,2-diacylhydrazines and for the analysis of reaction mixtures containing N2H4, RCOOH, and RCOOH · N2H4 along with the major substance.

Physicochemical Properties of 1,2-Diacylhydrazines Derived from Aliphatic Carboxylic Acids

The solubility and resistance to oxidation and hydrolysis of 1,2-diacylhydrazines derived from acetic, propionic, butyric, and valeric acids were studied in view of possible application of these compounds for concentrating nonferrous metals. The pK1 and pK2 values of the 1,2-diacylhydrazines were determined. The stability of conformers and the electron density distribution in the coordination-active moiety were estimated by SCF MO LCAO semiempirical calculations in the MNDO-PM3 approximation.

Physical and Chemical Properties of N-(2-Hydroxyethyl)alkylamines

Physical and chemical properties of N-(2-hydroxyethyl)alkylamines were studied, isotherms of a surface tension of homologous series of these compounds on a liquid-gas interface in water and hydrochloric acid were obtained.

Direct extraction of nickel from model sulfate solution with hydrazide of versatic tert-Carboxylic acids

Possibility of direct extraction of 0.66 g L–1 Ni(II), 0.048 g L–1 Co(II), and 0.024 g L–1 Zn(II) in the presence of the nine commonly accompanying elements from a model solution for underground sulfuric acid leaching of an oxidized Ni ore with a 0.4–0.6 M solution of a hydrazide of Versatic C15–C19 acids in kerosene was considered. The optimal conditions of extraction, extract washing to remove impurities, and re-extraction of Ni and Co were determined. It was found that the direct extraction of up to 90% of nickel, cobalt, and zinc is possible with an at least fivefold concentration in the extraction stage. The separation of Ni from Co and co-extracted Fe, Zn, and Mn is possible in the re-extraction stage by washing of the organic phase with a 0.5 M HCl solution.

Complexation of ethyl 2-aryl(alkyl)sulfonylamino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylates with nonferrous metal ions

Complexation of sulfonyl derivatives of the Gewald thiophenes (SGT) with Cu(II), Co(II), Ni(II), Zn(II), and Cd(II) ions in ammonia solutions was studied. The molar ratio method, the Job’s method of continuous variation, and coductometric titration revealed ratios [M(II)]: [SGT] = 1: 2. The composition of preparatively isolated complexes was confirmed by IR spectroscopy and elemental analysis data. Solubility product constants for precipitates of the complexes and complexation equilibrium constants were calculated. Solubility product constants for M(II) complexes was shown to be dependent on the nature of sulfonyl substituent in SGT series.

Physical and chemical properties of N′,N′-aliphatic acid dioctylhydrazides and their complexing with copper(II) ions

Some physical and chemical properties of aliphatic acid N′N′-dioctylhydrazides[RC(O)NHN(C8H17)2] (DOHs) were studied in comparison to 2-ethylhexanoic acid N′N′-dialkylhydrazides, namely, solubility, acid-base properties, entrainment with an aqueous phase, and partition factors depending on the medium and the acyl radical length. The pH ranges of maximal extraction of copper(II) complexes by DOHs to kerosene and the effect of ammonium salts on copper(II) extraction were determined. The compositions of extracted complexes were determined (Cu(II): DOH = 1: 1 and 1: 2); the extraction constant Kextr was calculated for the CuL2 complex with butyric acid N′N′-dioctylhydrazide.

Extraction and complexation of nonferrous metals with 3-substituted 2-sulfonylaminothiophenes

Trends of copper(II), nickel(II), cobalt(II), and zinc(II) extraction recovery from ammoniac solutions by 3-substituted 2-sulfonylaminothiophenes have been studied. The compositions and structures of extractable complexes have been determined. A mechanism has been proposed suggested for the recovery of nonferrous metals. Extraction constants have been calculated.

Physicochemical properties and complex formation of ethyl 2-aryl(methyl)sulfonylamino-4,5,6,7-tetrahydrobenzothiophene-3-carboxylates

Acid-base properties, solubility, and chemical stability of ethyl 2-aryl(methyl)sulfonylamino-4,5,6,7-tetrahydrobenzothiophene-3-carboxylates have been studied. Complexes of Cu(II), Co(II), and Ni(II) with one of the ligands have been prepared and isolated; their solubility products were determined.

Complexation of N-acyl-N′-(p-toluenesulfonyl)hydrazines with nonferrous metal ions in ammoniac media

The complexation of N-acyl-N′-(p-toluenesulfonyl)hydrazines (ASHs) with copper(II), cobalt(II), nickel(II), zinc(II), cadmium(II), and silver(I) ions in ammoniac media was studied. The reagents were shown to form compounds with [M]: [ASH] ratios of 1: 1 and 1: 2 in solutions. ASH complexes with metal ions were preparatively separated and identified. The quantitative characteristics of complexation equilibria—the solubility products of precipitates—were found. The effects of ammonium salts and the length of a radical on the completeness of precipitation of M(II) cations with ASH were studied.

Extraction of copper(II) with 1,2-diacylhydrazines in the presence of associated metals

Conditions of Cu(II), Zn(II), Ni(II), Co(II), and Fe(III) ions extraction (pH values, effect of reagent amount) with symmetrical 1,2-diacylhydrazines derived from straight-chain aliphatic carboxylic acids and α-branched higher carboxylic acids Versatic-10 were studied. The separation coefficients of element pairs and pH of half extraction were calculated. The values of [Cu(II)]: [reagent] ratios in extracted complexes were determined. 1,2-Diacylhydrazines were shown to be more selective extractants toward nonferrous metal ions as compared with carboxylic acids, while the branching and elongation of alkyl chain in the reagents enhances their extraction properties and compatibility with hydrocarbon solvents.