Catalytic flow-injection determination of copper at nanogram levels by using color formation of N-phenyl-p-phenylenediamine with m-phenylenediamine in the presence of pyridine and ammonia as activators

A spectrophotometric flow-injection method for determining copper(II) has been developed. It is based on the catalytic effect of copper(II) on the oxidative coupling of N-phenyl-p-phenylenediamine with m-phenylenediamine in the presence of hydrogen peroxide. Pyridine and ammonia as activators increased the absorbance for the copper(II)-catalyzed coloration, and the dye formed was stabilized by adding a non-ionic surfactant. The working range of the method was 0.1-2.0 ng ml(-1) of cooper(II) with a relative standard deviation 2.4% at a sampling rate of 30 h(-1). Interference from iron(III) was effectively suppressed by citric acid. Copper in natural water samples can be determined easily.     

Synthesis and properties of fluoronitroalcohols. Report 5. 1,5-difluoro-1,1,5,5-tetranitropentan-3-ol

Conclusions 1,5-Difluoro-1,1,5,5-tetranitropentan-3-ol was obtained by reduction of 1,5-difluoro-1,1,-5, 5-tetranitropentan-3-one with NaBH₄ in the presence of BF₃ etherate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 398–401, February, 1986.     

Reaction of 1-chloromethylisatin with indole

In the condensation of N-chloromethylisatin with indole and 2-methylindole in the presence of triethylamine, instead of the expected N-skatylisatins the products of their subsequent transformations with opening of the five-membered ring of isatin -o-(N-skatylamino)- and o[N-(2-methylskatyl)amino]benzoylcaproic acids —were isolated. In addition to the formation of these -keto acids, under the indicated conditions one observes dimerization of N-chloromethylisatin and N-chloromethyl-5-methylisatin to give 2-(1-isatinylmethyloxy-3H-indolin-3-one and 2-(5-methyl-1-isatinylmethyloxy)-5-methyl-3H-indolin-3-one, respectively, i.e., dimers containing isatin rings in lactam and lactim forms. The structures of the compounds were confirmed by IR, PMR, and mass-spectral data.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 217–220, February, 1977.     

Chemical structure of poly(ethylene terephthalate)–styrene and nylon–styrene graft copolymers prepared by radiation techniques

The graft copolymerizations of styrene onto poly(ethylene terephthalate) (PET) and nylon fibers were carried out by the mutual irradiation and preirradiation methods. True graft copolymers were isolated from the products by extraction and characterized by hydrolysis and osmometry. Among the swelling agents employed, methanol was most effective for increasing the extent of grafting onto PET. In both methods of the grafting, the molecular weight of polystyrene formed in the substrate matrix was higher than one million if no chain-transfer agent was added to the monomer solution. Similar to the case of radiation grafting onto poly(vinyl alcohol) and cellulose, the isolated graft copolymer carried only one branch per copolymer molecule in both cases. Of great interest is the particularly low extent of grafting in the case of PET–styrene. This should be attributed to the low sensitivity of PET to radiation. The grafting site on the mother polymer molecule is discussed on the basis of the solution behavior of the branch polymers separated from the backbone.     

Separation of gallic acid from Cornus officinalis Sieb. et Zucc by high-speed counter-current chromatography

Gallic acid was separated from a n-butanol extract of the fruit of Cornus officinalis Sieb. et Zucc by high-speed countercurrent chromatography in two steps using two solvent systems composed of ethyl-acetate-ethanol n-butanol-water (5:1.8:6, v/v/v) and ethyl acetate-ethanol-water (5:0.5:6, v/v/v) successively. From 1 g of n-butanol extract the method produced 60 mg of gallic acid at a purity of 97%.     

Zur „Rückdiffusion“ bei Quecksilberextrusionselektroden

An investigation has been carried out on the influence of the velocity of voltage change, of the radius of the capillary and of the size of the electrodes on the decrease of the peak current caused by back-diffusion in anodic amalgam voltammetry.