Single-component Solvents Research Articles

Electronic spectra and Zeeman effect of ruthenium phthalocyanine in Shpol'skii matrices

Electronic and Zeeman spectral properties of ruthenium phthalocyanine (RuPc) in a 4·2 K single-component solvent (n-octane) were investigated. The dynamic properties of the singlet and triplet states were studied at various low temperatures. The results show that both spectral and dynamic characteristics of the ligand-complexed RuPc are very similar to those of PdPc, although the latter required mixed-solvent matrices. The study also addressed the question of the role in ligands in the Pc complexes as well as that of the carrier solvent in the Shpol'skii matrices. Both, Zeeman as well as field free spectroscopy, show that RuPc and PdPc have comparable but different spin-orbit coupling strengths which are consistent with the respective intersystem crossing rates and the zero field splittings of the triplet states.

Effect of the central ion of octahedral transition metal complexes on their thin-layer chromatographic R F values

The R F values of twenty complexes of Cr III, Co III, Ru III, Rh III, Fe II, Co II, Ni II and Zn II containing ligands such as ethylenediamine-N,N′-diacetato-N,N′-di-3-propionato (eddadp), ethylenediaminetetra-3-propionato (edtp), 2,4-pentanedionato (acac), 1-phenyl-1,3-butanedionato ion (bzac) or α,α′-dipyridyl (dipy), were determined by thin-layer chromatography. Development was carried out with 22 single-component solvents. The results obtained for anionic and neutral complexes can best be explained by using the polarization power of the central ions of the complexes, assuming an adsorption separation mechanism.

Refractive indices and thermo-optical properties of dye laser solvents

By measuring the wavelength tuning of a distributed feedback dye laser, solvent refractive-index changes as small as 0.0002 may be determined. This technique hence allows precise measurement of refractive-index dependence on temperature (dn/dT) and therefore enables the thermo-optical properties of solvents used in dye lasers to be assessed. In addition to single component solvents, the thermo-optical properties of solvent mixtures and additives are reported here. The refractive-index change with temperature (dn/dT) is related to solvent density change with temperature (dq/dT) through molecular polarizability.

Effect of the geometrical configuration of facial and meridional isomers of cobalt(III) and chromium(III) complexes on their RF values

The R F values of eight pairs of facial and meridional of cobalt(III) and chromium(III) complexes have been determined by thin-layer chromatography with 21 solvent systems and by paper chromatography with 26 solvent systems. In the thin-layer chromatographic separations on silica gel the meridional isomers always exhibited higher R F values when single component solvent systems were used. On the contrary, with multicomponent solvent systems, in 30% of cases the elution order of the isomers was reversed. In paper chromatographic separations with solvent systems not containing strong acids the meridional isomers were found to exhibit higher R F values. However, when solvent systems containing strong acids were used in some cases the elution order was reversed. Possible mechanisms for the separation of those isomers are considered.

Flexibilität und hydrodynamische eigenschaften von polymethylmethacrylat in binären mischlösungsmitteln

AbstractLight scattering and viscosity measurements of poly(methyl methacrylate) have been carried out, in order to investigate the correlation of unperturbed dimensions and intrinsic viscosity of the polymer relative to the thermodynamic properties of solvent mixtures as compared to results obtained in single component solvents. The unperturbed dimensions of the polymer turned out to be unaffected by the mixed solvent, whereas a strong dependence of the hydrodynamic radius on the enthalpy of mixing of the two solvent components was observed. Hence unequivocal conclusions about the chain structure of the dissolved polymer cannot be drawn from hydrodynamic measurements in mixed solvents. If values of the viscosity constant K0 in these systems in the vicinity of the Θ‐point are extrapolated according to the Burchard‐Stockmayer‐Fixman equation, they do not agree with data measured at T = Θ.

Collaborative testing of a gas chromatographic charcoal tube method for seven organic solvents.

The National Institute for Occupational Safety and Health has undertaken a program to provide reliable sampling and analytical methods for a number of industrial hygiene uses. Recommendation of methods to the Department of Labor for compliance testing and inclusion of methods in critera for Recommended Standards for Occupational Exposures are two prime areas of utilization. This paper presents the results of our initial efforts in collaborative testing. The method is a charcal tube sampling procedure and a gas chromatographic analytical technique. Samples of seven single component solvents which included benzene, carbon tetrachloride, chloroform, dioxane, ethylene dichloride, trichloroethylene, and xylene along with two solvent mixtures which consisted of a benzene-xylene combination and an ethylene dichloride-trichloroethylene conbination were tested in two phases by 15 participating laboratories. The data analysis indicates the overalll error associated with the method and identifies sources of error within each segment of the method.

Thin-layer chromatography as a pilot technique for rapid column chromatography

It is proposed to utilize thin-layer chromatography for the choice of adsorbent, solvent and working conditions in column chromatography (liquid-solid chromatography), as thin-layer chromatography facilitates manipulation, is economical and, unlike column chromatography, enables numerous specific detection reactions to be used. Transfer formulae are developed whose validity is shown by several practical examples. The transfer of conditions and separations poses few problems, when single-component solvents are used. Under certain conditions (N-chamber), the use of solvent mixtures may lead to uncertainties. The activity of the plate and the column must be controlled and the water concentration of the column chromatographic solvent must be “isotonic” with the column activity. On the other hand, the column activity can be adjusted by using different water concentrations in the solvent.

Improved separation in thin-layer chromatography using a single-component solvent in an unsaturated chamber

An unexpected observation was made during an interlaboratory investigation on R F standardisation. Comparing the results which were found on silica gel layers obtained in saturated chambers with those in unsaturated chambers and using benzene as solvent, it was observed that, without exception, the unsaturated chambers gave better separations than the saturated ones.

Thin Layer Chromatography of Synthetic Dyes (III)

Oil Orange SS (C.I. 12100) and Oil Red XO (C.I. 12140) have not clearly been separated from each other by thin layer chromatography on silica gel with a single-component solvent. In this paper, several solvent systems for separating these dyes were investigated. The solvent system giving the best result was the mixture being composed of iso-amyl acetate+n-hexane (15: 10), and it gave clear separation especially for a mixture of Oil Yellow AB (C.I. 11380), Oil Yellow OB (C.I. 11390), Oil Orange SS and Oil Red XO. The Rf values were in order of XO>SS>OB>AB and it was concluded that the Rf values of dyes containing methyl group increase as the number of the group increases. The Rf values of 18 oil-soluble dyes are tabulated (Table 2).