Фосфоресценция кислорода при возбуждении на длине волны 765 nm

Capillary gas chromatography — Fourier transform infrared spectroscopy combined with capillary gas chromatography — mass spectrometry is employed for the analysis of major volatile products in the γ-radiolysis of isomeric nitrophenol solutions in carbon tetrachloride. Isomeric di- and trichlorophenols, chloronitrophenols and dichloroisocyanatobenzenes in addition to those formed with m- and p-isomers, are among the important products formed in the solution of o-nitrophenol in carbon tetrachloride. Formation of dichloroisocyanatobenzene is explained by the interaction of dichlorocarbene with the nitro group followed by the ipso-substitution of OH and H atom by chlorine atom.

Uranium (VI) extraction from sulphuric acid solutions with tri- n-octylamine solutions in benzene and carbon tetrachloride

Using standing-wave techniques, the dielectric constant ( epsilon ') and the dielectric loss ( epsilon ") of dilute solutions of N,N-dimethylformamide (DMF) in benzene, dioxane and carbon tetrachloride have been measured at 9.987 GHz at 25, 35, 45 and 55 degrees C. Following the single-frequency concentration variational method, the dielectric relaxation time ( tau ) and the dipole moment ( mu ) at various temperatures (25, 35, 45 and 55 degrees C) have been evaluated. From these studies the monomer structure of DMF in various solutions (benzene, dioxane and carbon tetrachloride) has been inferred and for a DMF-in-benzene solution a solute-solvent type of molecular association has been found. The energy parameters ( Delta Fepsilon , Delta Hepsilon and Delta Sepsilon ) for the dielectric relaxation of DMF in benzene, dioxane and carbon tetrachloride solutions have been calculated and compared with the corresponding viscosity parameters. A comparison between these two sets of parameters shows that the dielectric relaxation, like the viscous flow, can be considered as a rate process.

The system iodine–n-butyl vinyl ether in carbon tetrachloride, diethyl ether, and ethylene dichloride has been studied. The species l4 exists in solutions of iodine in these solvents but is probably not significant in the polymerisation.The absence of any spectral evidence for l3– in polymerising solutions in carbon tetrachloride and diethyl ether suggests that the stationary state concentration of active monomer during polymerisation is only very small. The low conductivities of solutions of iodine and monomer in carbon tetrachloride are in accord with this conclusion.The first and second ionisation potentials of n-butyl vinyl ether are reported. The predicted absorption maxima of the n-butyl vinyl ether–iodine σ- and π-complexes show poor agreement with the experimentally observed absorption bands which have previously been attributed to these complexes. Conductivity measurements show that the termination of polymerisation is accompanied or followed by large increases in the concentration of ions in the solutions. During polymerisation the conductivities of ethylene dichloride solutions are much higher than those of carbon tetrachloride solutions in accord with the higher dielectric constant and the greater rates of polymerisation for the former.

Equilibrium constants of U(VI)-tri-isooctylammonium acetate complexes in various organic diluents

Irradiation of dilute solution of cis‐1,4‐polybutadiene in carbon tetrachloride with UV light in the presence of air causes fast formation of white precipitate—insoluble gel. It has been shown that carbon tetrachloride was effective photosensitizer for oxidation of cis‐1,4‐polybutadiene. Separated sol and gel fractions were analysed by infrared spectroscopy for better understanding of gelation process and structure of the gel. Three stages were detected in the process of oxidative photogelation of cis‐1,4‐polybutadiene in carbon tetrachloride solution: pre‐gelation(sol‐stage), gelation (sol/gel‐stage) and post‐gelation (gel‐stage). In the first stage intensive photooxidative reactions between cis‐1,4‐polybutadiene, carbon tetrachloride and oxygen take place, giving products with high content of hydroperoxide and bounded chlorine. When hydroperoxide and chlorine content reached critical value, precipitation‐gelation takes place. It is proposed sequence of free radical reactions which involves: photolysis of carbon tetrachloride to free radicals, addition of solvent radicals to the double bonds of rubber followed by combining of resulting radicals with oxigen to chlorinated polymeric peroxy radicals. Initially formed gel is peroxidic in nature, which photolyses to the more stabile ether gel by prolonged irradiation.

I.r. and Raman spectra of 3,4-dimethyl-3,4-dinitrohexane (in the solid and solution states) are reported and assignment of frequencies made. It is assumed that the higher melting isomer has the meso- and the lower melting isomer the (±)-configuration. Comparison of the Raman and i.r. spectra of both the solid and solution states of meso-3,4-dimethyl-3,4-dinitrohexane shows that this compound exists in the gauche conformation in the solid state but as a mixture of gauche and trans rotamers in solution. Dipole moments in different solvents (benzene, carbon tetrachloride, and cyclohexane) at different temperatures and molar Kerr constants (in carbon tetrachloride and benzene) are also reported. Analysis of the dielectric data shows that at 25°C, meso-3,4-dimethyl-3,4-dinitrohexane exists as a rotameric mixture of 53%gauche and 47%trans in carbon tetrachloride solution, and 80%gauche and 20%trans in benzene solution. On the other hand, our spectral data suggest that in the solid state (±)-3,4-dimethyl-3,4-dinitrohexane exists as a mixture of the two possible rotamers in which the nitro groups are gauche to each other. In non-polar solvents like carbon tetrachloride, an additional rotamer, in which the nitro groups are trans to each other, appears. Analysis of the dipole moment data suggests that the combined proportion of the 'gauche' rotamers is 24% in carbon tetrachloride and 43% in benzene.

Uranium (VI) extraction from sulphuric acid solutions with mono-2,6,8-trimethylnonyl-4- and mono- n-butylphosphoric acids solutions in benzene and carbon tetrachloride

The effect of solvents on formaldehyde adsorption performance on pristine and Pd doped on single-walled carbon nanotube using density functional theory

In consideration of the flat-sheet structure known as a secondary structure of peptides and proteins, the self association of N-acyl α-amino acid derivatives may reasonably be expected to occur in non-aqueous media. To confirm the structure of dynamically formed molecular complexes, spectral studies of N-acetylvaline tert-butyl ester (1) in a carbon tetrachloride solution were carried out. A split of the amide NH resonance into two 1H nmr signals for the D and L enantiomers, termed self-induced non-equivalence, was observed when the solute was enantiomerically enriched in the solution. A concentration study of 1H and 13C-NMR showed the diastereomeric dimers, whose associative interactions are bidentate NH--O=C (ester) hydrogen bonds, to be in the enantiomeric solutions. Ir spectra confirmed the stability difference between the diastereomeric dimers by an external comparison of optically pure and racemic samples in the carbon tetrachloride solution.The association stereoselectivity of solute 1 was applied to the design of chromatographic phase systems. When racemic solute 1 is injected into a non-chiral silica gel column using mobile phase solvent containing chiral solute 1 as an additive component, the racemate should interact with chiral solute 1 added to the mobile phase solvent, while passing through the column, to form transient diastereomeric dimers as observed in solution, and be separated. Self association-induced resolution was confirmed experimentally using radiolabelled solute 1 and the radioactivity detection.Attempts were made to widen the scope of application involved in the hydrogen-bond association mode to chiral recognition through the development of other resolving agents. N-Acetylvaline tert-butylamide was found to separate the homologues of N-acyl α-amino acid esters. Tartaric esters and amides were found capable of separating a variety of enantiomeric compounds in non-aqueous media.

The kinetics of the polymerization of styrene, initiated by anhydrous perchloric acid in carbon tetrachloride solution and in mixtures of methylene chloride and carbon tetrachloride, have been studied by NMR and GLC methods. In carbon tetrachloride the reaction is zeroth order. The kinetics, together with the known effects of dielectric constant and pressure on the reaction rate, suggest that the rate-determining step may be the formation of a carbonium perchlorate ion-pair, associated with neutral molecules of styrene.

Small amounts of copper in rubber latex can be determined by following a dry-ashing procedure for removal of organic matter and concluding with a colorimetric determination of the copper in the ash. Provided the ignition is not undubly prolonged, the ashing temperature can safely rise to 800° C, and recovery of the copper is complete from the ash when a mixture of nitric and hydrochloric acids is used. Results are slightly higher than those obtained by the wet oxidation process. Assay of the copper can be carried out on the solution of the ash, either in aqueous medium or in carbon tetrachloride solution, depending on the extent of interference anticipated from iron and insoluble ingredients, such as clay, and on the degree of accuracy required. Visual color matching in aqueous solution is simpler and quicker, but insoluble material may give rise to considerable personal error. In aqueous solution, the copper equivalent of ferric iron is about 1/100, i.e., the coloration is about 100 times more intense for copper than for iron. for more accurate work, measurement of the color of a carbon tetrachloride solution of the copper diethyldithiocarbamate complex by means of a suitable colorimeter is recommended. The tendency of the complex to fade is overcome by replacing the sodium diethyldithiocarbamate by the zinc salt dissolved in carbon tetrachloride. In such a solution the copper equivalent of ferric iron is about 1/1000, but actual experimental conditions can vary this figure between wide limits. A more satisfactory procedure is, therefore, to measure the total color developed in carbon tetrachloride, and then bleach out the color due to copper with potassium cyanide. The residual (interfering) colors can thus be estimated, and the difference between the readings gives a direct measure of the concentrations of copper in the test solution.

FT-NIR absorption spectra of octanoic acid in the liquid phase were recorded over a temperature range of 15 - 92 degree(s)C. The spectra were used to calculate integrated intensities due to the first overtone of an OH stretching mode of the free acid ((nu) OH f ). Next, we determined the mole absorption coefficient ((epsilon) OH f ) for the band through a series of measurements in carbon tetrachloride (CCl 4 ) solution at very low concentrations. The value of (epsilon) OH f was utilized to calculate the degree of dissociation ((alpha) ) and thermodynamical parameters of the acid.

Spectroscopic studies of long chain fatty acids. Pyridine—fatty acid—carbon tetrachloride system

U.v. irradiation of ethyl 2-diazo-3-(4,4-dimethyloxazolidin-3-yl)-3-oxopropionate (3) gives a product whose spectroscopic properties and reactions are consistent with its formulation as ethyl 2,2-dimethyl-7-oxo-4-oxa-1-azabicyclo[3.2.0]heptane-6-carboxylate (1d). Nucleophilic reagents rapidly cleave the β-lactam ring of compound (1d)[e.g. treatment with benzylamine yields the benzylamide (4a)]. In solution in carbon tetrachloride (1d) is converted into the 14-membered ring dilactone (7). The structures of compounds (4a) and (7) are supported by independent syntheses.