A. V. Radushev

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.

Crystal structures of two copper(II) complexes with N,N-diethylbenzhydrazide

The copper(II) complexes with N,N-diethylbenzhydrazide, [Cu(C6H5CONHN(C2H5)2)]Cl2 (I) and Cu(C6H5CONN(C2H5)2)2 (II), have been studied by X-ray diffraction analysis. In the both compounds, the reactant acts as a bidentate (O, N(2)) ligand, forming five-membered chelate rings with copper. In cationic complex I, the O→Cu and N→Cu bond lengths are 1.954(2) and 2.070(3) Å, respectively, and the O(1)CuN(2) chelate angle is 81.89(10°. The Cl− ions are in the coordination sphere of copper (Cu-Cl, 2.1974(11) and 2.2178(10) Å). The chelate ring has an envelope conformation with the copper atom in the flap position. The coordination polyhedron of the copper atom is a strongly distorted tetrahedron. Neutral complex II is an inner complex salt. The reactant forms with copper two planar chelate rings. The Cu-O and N→Cu bond lengths are 1.8901(9) and 2.0175(11) Å, respectively, and the O(1)CuN(2) chelate cycle is 83.70(4)°. Complex II is planar, and the coordination polygon of the copper atom is a parallelogram. The thermal stability of complexes I and II has been studied.

Extraction of copper(II) with N,N-diethylbenzohydrazide

Extraction of Cu(II) with N,N-diethylbenzohydrazide and the effect of ammonium salts on this process were studied. The composition and structure of the complex being extracted was analyzed.

Extraction and complexing of copper(II) with benzoic acid N,N-dihexylhydrazide

The solubility and acid-base properties of benzoic acid N,N-dihexylhydrazide (BDHH) were studied. The extraction of copper(II), cobalt(II), nickel(II), zinc(II), iron(III), platinum(II), platinum(IV), chromium(III), chromium(VI), palladium(II), and molybdenum(VI) with this reagent was studied. It was shown that BDHH most efficiently extracts copper(II) from ammonia solutions and chromium(VI) from sulfuric acid solutions. In the extraction of copper(II), complexes with the [Cu(II)]: [BDHH] = 1: 1 and 1: 2 stoichiometries were found to form. The structure of the 1: 2 complex was suggested proceeding from its IR spectra. A copper(II) extraction isotherm was plotted.

Extraction of copper(II) with N-(para-tert-butylbenzoyl)-N′,N′-dialkylhydrazines

Extraction of Cu(II), Co(II), Ni(II), and Zn(II) with N-(para-tert-butylbenzoyl)-N′,N′-dialkylhydrazines was studied. In contrast to other listed elements, copper(II) is extracted with these reagents in a wide pH range and NH3 concentrations, which provides its selective separation. Effect of chain length of the N′,N′-alkyl groups and solvent nature on copper extraction and its stripping conditions were determined. Extraction constants were calculated. Ammonium salts decrease the extraction degree of copper(II). The studied reagents are superior to the known industrial reagent of β-diketone class, LIX 54, in terms of copper(II) extraction efficiency from ammonia media.

Rhenium(VII) extraction with 2-ethylhexanoic acid N,N-dialkylhydrazides from acidic solutions

Rhenium(VII) extraction with 2-ethylhexanoic acid N′,N′-dialkylhydrazides in kerosene from acidic media was studied. Optimal extraction conditions were established depending on H2SO4, HCl and extractant concentrations and the composition of extracted complexes. A mechanism of perrhenate ion extraction and back-extraction with ammonium solutions was proposed.

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.

Extraction and complexation of Cu(II) with undecanoic acid N,N -diethylhydrazide

A new reagent, undecanoic acid N,N-diethylhydrazide, was synthesized, and its pKa1 was determined. The reagent recovers Cu(II) to 99–100% from solutions whose acidity ranges from pH 6 to 1 M NH3. Copper(II) is extracted in the form of a neutral complex of the composition Cu(II):reagent = 1:2. The reagent is incorporated in the complex in the deprotonated form. An equation for the extraction of Cu(II) from ammonia solutions was suggested. The extraction isotherm was constructred. Ammonium salts, when present in solution, considerably decrease the degree of copper extraction. The reagent is less efficient extractant of copper than N,N-diethylbenzhydrazide.

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.