Two new spectrophotometric reagents for copper

Two ferroin-type compounds are proposed as spectrophotometric reagents for copper(I): 6-methyl-2-pyridylhydrazidine, which forms a yellow complex with lambda(max) 426 nm and molar absorptivity 700 l.mole(-1).mm(-1), and 3-(6-methyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine, which forms a red-orange complex with (lambda)max 492 nm and molar absorptivity of 955 l.mole(-1).mm(-1). These reagents are specific for copper and the complexes can be extracted into isopentanol for increased sensitivity.     

The modes of combustion of copper nanopowders

It was shown that the synthesis of Cu nanopowder by thermal decomposition afforded chemically purer (without oxides) and finer (specific surface value ～45 m2 g^?1) product than the synthesis by chemical reduction. The latter method leads to pyrophoric nanopowders containing detectable amounts of copper oxides.     

The oxidation of isopropylbenzene in the presence of copper nanopowders

The oxidation of isopropylbenzene with oxygen in the presence of copper nanopowders prepared under various wireelectrical explosion conditions was studied. The oxidative conversion of isopropylbenzene was observed only for nanopowders with a linear function of oxygen absorption. Holding copper nanopowders in a vacuum stimulated their initiating activity. A lower initial temperature of the oxidation of nanopowders in air corresponded to a higher rate of oxygen absorption by isopropylbenzene. The amount of absorbed oxygen was not equivalent to the conversion of isopropylbenzene.     

Dissolution of copper nanopowders in inorganic biological media

Electroexplosive copper nanopowders with dispersion 3.2, 5.0, 6.8, and 12.0 m² g⁻¹ were dissolved in distilled water, physiological (saline) solution, and phosphate buffer. From experimentally determined concentrations of dissolved copper and pH of the solution kinetic curves were constructed and kinetic and thermodynamic analysis was performed of the possible chemical reactions. The influence of the powder dispersion and the nature of solvents on the kinetic parameters of dissolution were considered.     

Oxidation of copper nanopowders on heating in air

The morphology and structure of copper nanopowders produced by electrical explosion of conductors are considered. The regularities of nanopowder oxidation in air were studied during linear and isothermal heating. The characteristics of initial powders in relation to the kinetic oxidation parameters were determined and the dependence of phase composition of the products of nanopowder oxidation on the heating conditions and dispersity of initial powders was found.     

Effect of stabilizers on the tolerance of copper nanopowders for oxidation by molecular oxygen

The effect of various stabilizers, phenol, 1-naphthol, hydroquinone, hydroxylamine sulfate, metol, guanidine, and dimethylphenylbenzylammonium chloride, on the rate of oxidation of copper nanopowders by molecular oxygen was studied.     

Substituted 2-thiophenealdehyde-2-benzothiazolyl-hydrazones as analytical reagents for copper

The analytical properties of 5-chloro-, 5-bromo- and 5-methyl-2-thiophenealdehyde-2-benzothiazolylhydrazone (CTBH, BTBH and MTBH, respectively), are compared with those of 2-thiophenealdehyde-2-benzothiazolylhydrazone (TBH). The acid dissociation constants have been determined, and the 5-substituent effect is discussed. The complex formation of the reagents with several metal ions has been examined spectrophotometrically. Extraction—spectrophotometric determinations of traces of copper are proposed. The copper complexes can be extracted quantitatively into benzene over wide pH ranges (from weakly acidic to alkaline medium) and the molar absorptivities are high (4–5· 10⁴ l mol^-1 cm^-1). The complexes formed are 1:2 (copper:ligand) in all cases. There are few interferences from common ions except silver(I), mercury(II), thiocyanate and citrate.     

Effect of various factors on the dispersity of copper nanopowders produced by reduction of copper salts with glycerol

Effect of the nature of a copper salt and initiators on the dispersity of copper powders was studied. The dispersity was determined by electron microscopy, X-ray phase analysis, and method of small-angle X-ray scattering, as well as from the specific surface area found by the BET technique.     

Organic and inorganic binder-coating properties for immobilization of photocatalytic ZnO nanopowders

Research on Chemical Intermediates - Five kinds of organic binders, three kinds of inorganic binders, and four kinds of organic–inorganic double-layer binders were prepared to immobilize...     

N-Aryl-3-Aminopropionic acids as selective reagents for the determination of copper in metallurgical products

Analytical characteristics of N,N-di(2-carboxyethyl)aniline (I), N,N-di(2-carboxyethyl)-3,4-xylidine (II), N-(2-carboxyethyl)anthranilic acid (III), N,N-di(2-carboxyethyl)-4,5-dimethylaminoazobenzene-4-sulfonic acid (IV), and N-(2-carbamoylethyl)anthranilic acid (V) were studied. The factors affecting the selectivity of I–V for Cu(II) ions (basicity of the amino group, nature and positions of substituents in the benzene ring, and geometry of chelate cycles) were analyzed. The optimum conditions were found and procedures were developed for the spectro-photometric determination of copper in metallurgical products. The high selectivity of I–V for Cu(II) ions allows the determination without preliminary separation of concomitant components in aqueous solutions without organic solvents. Compound II exhibits the best analytical characteristics: the analytical range of copper 3–20 mg/L, detection limit 0.7 mg/L, ( = 252 nm) = 3290 L mol^–1 cm^–1, and pH 6.0 (ammonia-acetate buffer solution).Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 3, 2005, pp. 271–277.Original Russian Text Copyright © 2005 by Neudachina, Osintseva, Skorik, Vshivkov.     

A study of the reactivity of copper nanopowders in their reaction with glacial acetic acid

The reactivity of copper nanopowders obtained by mechanical treatment or electric explosion of a conductor was studied in their reaction with glacial acetic acid. Two parameters were used to evaluate the reactivity: heat effect of the reaction and the maximum rate of heat release.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 12, 2004, pp. 1937–1941.Original Russian Text Copyright © 2004 by Mikubaeva, Kobotaeva, Sirotkina.     

Physicochemical properties of compounds of alkyl sulfates and cationic copper(II) complexes with some organic reagents

Compounds of alkyl sulfates and cationic copper(II) complexes with some organic reagents (pyridine, 1,10-phenanthroline, 2,2'-dipyridyl) were prepared, and their physicochemical characteristics (composition, thermal stability, solubility) were determined. The synthesized compounds are poorly soluble (solubility product K_S = n×10^–20–n×10^–22) and thermally stable (90–260°С). An effect of the hydrophobilicity of alkyl sulfates on the UV characteristics of the copper(II)–organic reagent systems and on the solubility of the studied compounds was evaluated.     

New reagents for the synthesis of a series of ferrocenoyl functionalized copper and silver chalcogenolate complexes

A series of silylated ferrocenoyl chalcogenide reagents, FcC(O)ESiMe(3) (E = S, Se, Te; Fc = ferrocene), can be prepared in very good yield from FcC(O)Cl and LiESiMe(3). These reagents are used in the preparation of triphenylphosphine-ligated copper and silver ferrocenoyl thiolate and selenolate complexes, [M(4)(E{O}CFc)(4)(PPh(3))(4)], (M = Cu, Ag; E = S, Se) and [Cu(2)(mu-Se{O}CFc)(2)(PPh(3))(3)] from solubilized copper(i) and silver(i) acetate. The structures of these complexes have been determined via single-crystal X-ray diffraction. The driving force for these reactions is the thermodynamically favorable formation and elimination of AcOSiMe(3). The synthesis and characterization of both starting reagents and cluster complexes are discussed.     

Bathophenanthrolinedisulphonic acid and bathocuproinedisulphonic acid, water soluble reagents for iron and copper

Bathophenanthrolinedisulphonic acid and bathocuproinedisulphonic acid have been isolated in solid form as sodium salts and characterised. Both materials retain the high sensitivity of the parent materials as spectrophotometric reagents, for iron and copper respectively. They are water soluble and unlike the parent reagents may be used in aqueous perchlorate solutions. Interferences are about the same as with the parent reagents, but the pH range for maximum colour formation extends two pH units further into the alkaline region. Iron^II tribathophenanthrolinedi-sulphonic acid is an excellent oxidation-reduction indicator, changing sharply from red to green in the cerate titration of iron^II; it may be used in solutions containing perchloric acid.     

General approach to the coupling of organoindium reagents with imines via copper catalysis

[reaction: see text] A copper-catalyzed three-component coupling of organoindium reagents with imines and acid chlorides is described. This mild carbon-carbon bond forming reaction requires only one-third of an equivalent of indium reagent to proceed in high yield, with the sole byproduct being indium trichloride. The reaction demonstrates broad generality, with aryl-, heteroaryl-, vinyl-, and alkylindiums, as well as functionalized imines and acid chlorides, all providing alpha-substituted amides or N-protected amines in a single step.     

Inorganic thin-film combinatorial studies for rapidly optimising functional properties

Combinatorial chemistry is now commonplace in the pharmaceutical industry and applied rigorously in the discovery of drugs. Within materials science, combinatorial methods have been widely applied in investigating thin-films and since its re-introduction in the mid 90's more than 20 new families of materials have been discovered. Yet, given the high diversity of states that can be produced in a single deposition, such methods are now being used more prominently to optimise functional properties of existing materials; having been applied in a variety of fields. In this review we will cover the key developments in bandgap, ferro/di-electric, fuel cell anode/ cathode, H(2) storage, hardness, Li battery electrodes, luminescence, transparent ferro-magnetic, photocatalytic, photovoltaic, shape-memory, transparent conducting oxide and thermo-electric materials optimisation. The critical review focuses on how functional-property relationships have been derived from combinatorial studies (217 references).     

New protocol for allylic substitution with aryl and alkenyl copper reagents derived from organolithiums

Substitution of allylic picolinoates with copper reagents derived from sp²-carbon-lithiums and CuBr·Me₂S was established to furnish anti S_N2′ products with almost perfect regioselectivity and chirality transfer. The preparations of organolithiums such as lithium-halogen exchange and ortho lithiation were coupled to the substitution to install various sp²-carbon groups, which include Ph, 2,6-Me₂C₆H₃, 4-Me-2,6-(MOMO)C₆H₂, and cis and trans 1-heptenyl groups.     

Inorganic analysis in organic solvents : 8-hydroxyquinaldine as a reagent for the determination of copper

A new method is descibed forthe determination of copper. Fom a suitable solution, copper is extracted as its 8-hydroxyquinaldine complex into chloroform. The solution is diluted with an equal volume of benzene and passed through an activated alumina chromatographic column, whereupon all the 8-hydroxyquinaldates, except that of chromium, are adsorbed. Copper is eluted completely by developing the column with a 0.5% solution of 8-hydroxyquinaldine in that solvent mixture. The optical density of the cluate is measured at 400 mμ with respect to the solvent. Iron, molybdenum and vanadium interfere, but interference due to iron and molybdenum is readily overcome by a simple preliminary treatmont.