Synergism in the extraction of scandium

Synergism in the extraction of scandium by a mixture of di-2-ethylhexyl phosphoric acid and a β-diketone has been studied. The nature of the extracted species has been investigated. The effect of temperature on extraction has been studied and synergism has been explained on the basis of thermodynamic parameters of the extraction process.     

Poly (vinyl chloride) decomposition in solution

Thermal degradation of PVC in various solvents at 180° has been observed to be in the following order: benzonitrite > nitrobenzene > cyclohexanone > dioctyl phthalate > α-bromonaphthalane > decahydronaphthalene. The effect has been explained on the basis of β-eliminations of E₁-type favoured by polar solvents. An inhibition in PVC degradation has been observed in nitrobenzene containing stationary hydrogen chloride gas. The deceleration in degradation by predissolved HCl has been accounted for as a Mass Law effect.     

Kinetics and mechanism of oxidation of sugars by quinquevalent vanadium in binary mixture solvents of DMSO–water and acetic acid–water in H2SO4 medium

The kinetics of oxidation of aldosugars and ketosugar by quinquevalent vanadium in binary mixtures of DMSO–water and acetic acid–water in sulfuric acid medium have been studied. The reaction is first order in both oxidant and substrate. The effect of acidity on the reaction kinetics has been determined. The effect of acidity shows a clear difference. The ketose has a unit dependence, whereas aldoses have a 0.5 dependence in H₀. The role of solvent in these reactions has also been studied, and the effect of temperature on these reactions has been determined. A suitable mechanism has been postulated taking all the observed facts into consideration.     

Laser-spectrochromatographic identification of isomer in mixture

The combined “Gas Chromatograph — Laser Optoacoustic Spectrometer” (GC-LOAS) has been used to perform selective analysis of a mixture of fatty acid esters stereocisomers and a mixture of methylcyclopentadiene positional isomers. The GCLOAS system allows simultaneous recording of the retention time of the components in the mixture under analysis and their IR absorption spectra in the spectral operating range of the ¹²CO₂, ¹³CO₂ and HeNe lasers. It has been shown that the hydrogenated sample of fatty acids contains a lot of trans-isomer. Its content has been quantitatively estimated. The identification of methylcyclopentadiene isomers (both monomers and dimers) has been carried out, too.     

Twinning in macroscopic polymer single crystals

Twinning in macroscopic single crystals of poly(TSHD) has been investigated using scanning electron microscopy. Two particular chain-axis rotation twins have been identified unambiguously. They have K₁ twinning planes of (012) and (212). It is also thought that twins with K₁ planes of (21 2) and (202) may possibly occur. The possible mechanisms of twinning in polymer crystals have been discussed and chain-axis rotation twinning in poly(TSHD) has been compared with a similar type of deformation that has been suggested to take place in polyethylene crystals.     

Ethanol loading in an inductively coupled plasma

Changes to the fundamental and analytical parameters of a plasma have been investigated when ethanol has been added to aqueous or organic solutions. Excitation temperature, electron number density, and intensity of the H line increased when ethanol has been added to aqueous solutions, while an electron density decrease and signal reduction have been found when ethanol has been added to xylene. The sensitivity has been improved for all ethanol concentrations when water has been the solvent, but the reverse has been found for xylene solutions.     

Determination of energizers in energy drinks

The method of UV/VIS derivative spectrophotometry for the determination of caffeine and B vitamins in energy drinks after solid phase extraction has been developed. Caffeine has been determined in the mixture with B₂ vitamin with zero-crossing technique from the I derivative spectra (λ = 266.8 nm), and B₃ in mixture with B₆ vitamin from the II derivative spectra (λ = 280.1 nm). B₁₂ vitamin has also been determined in a three-component mixture with vitamins B₃ and B₆. Taurine in drinks has been determined from the basic spectra after derivatization with ninhydrin (λ = 570 nm).     

The Spectrophotometric Determination of Sc in Eriochrome Canine R(Chrome azurol s)- Phosphatidl Choline System

Abstract

Eriochrome cyanine R(chrome azurol S) is used as a color reagent to determine Sc in the presence of phosphatidyl choline, σ = 3.7 × 10⁴ (4.5 × 10⁴). This method has been connected to extraction separation to determine Sc in the presence of rare earth elements, and good results have been obtained.

Phosphatidyl choline(PC) is a biochemical reagent, which can be used as a surfactant. It has been reported that chrome azurol S(CAS) can be used to determine Be in the presence of PC¹ but it has not been reported that eriochrome cyanine R(ECR) and CAS can be used to determine Sc in the presence of PC. This paper has put forward a method by which Sc can be determined. ECR (CAB) has been used as a color reagent and PC as a surfactant. Conditional experiments have been made and this method has been connected to extraction separation. Tributyl phosphate (TBP) extracts Sc from rare earth elements to make a determination and good results have been obtained.     

Radium isotopes in suspended matter in an estuarine system in the southwest of Spain

The presence of²²⁶Ra and²²⁴Ra in suspended matter from an estuarine system which surrounds a phosphate fertilizer complex has been investigated. The results have confirmed an important radioactive impact from the industrial complex, since up to 2.5 Bq²²⁶Ra/g suspended matter (dry) has been measured. The influence of tides and seasonal conditions, through changes in salinity, has been found to be relevant. The distribution coefficients for²²⁶Ra between the suspended matter and the river water have been calculated. The values are in agreement by order of magnitude with those found in the literature, but they clearly depend on tidal state and seasonal conditions.     

Extraction-chromatographic determination of sulfonated azo dyes in aqueous solutions

The extraction of sulfonated azo dyes E102, E110, E122, E124, and E129 from aqueous solutions using hydrophilic solvents and their mixtures in the presence of a salting-out agent (ammonium sulphate) has been studied. Some regularities of extraction have been revealed. The composition of the mobile phase has been optimized and a procedure has been proposed for the identification and determination of the dyes in aqueous solutions by thin-layer chromatography in concentrations of 0.1–0.01 μg/L. An office scanner and a personal computer have been used to process the results of the separate determination of the dyes.     

Cathodic reduction of carbon disulfide in aprotic medium

The cathodic reduction of CS₂ at platinum electrodes has been studied in aprotic media (DMF and MeCN). It has been established that in an irreversible one-electron reduction CS and CS₃^2? are formed. Evidence for the former has been obtained via the formation of the RhCl(CS)(PPh₃)₂ complex and for the latter via u.v. and i.r. spectra. Furthermore evidence has been gained for a slow chemical reaction, following the charge transfer step, between CS and CS₃^2? to form a cyclic dianion.     

Theoretical calculation of the optimum separation in thin-layer chromatography

Summary Up to now the optimum composition of a binary mobile phase for separation in thin-layer chromatography has been determined mainly by the method of successive trials. In this paper a simple way is presented to determine the mobile phase composition and the maximum difference in the R_M values of two substances. The equation introduced has been illustrated with examples of adsorption thin-layer chromatography on magnesium silicate. Calculation of the largest difference in the R_M values of two substances in relation to the composition of the binary mobile phase has been compared with the corresponding values determined experimentally. A good agreement of the obtained theoretical data and experimental values has been found.     

Self-organizing silane-siloxane copolymers: Synthesis and behavior in the block and monomolecular layers

Trans tactic cyclolinear organosilicon copolymers with a regular alternation of decamethylcyclohexasiloxane and decamethylcyclosilane units have been synthesized by the heterofunctional polycondensation of trans-2,8-dihydroxydecamethylcyclohexasiloxane with 1,3-or 1,4-dichlorodecamethylcyclohexasilanes. The structure of the copolymers has been studied by ¹H and ²⁹Si NMR, and IR spectroscopy; molecular mass measurements; and elemental analysis. The phase behavior of these copolymers in the block has been examined by DSC, X-ray diffraction, and polarization optical microscopy. It has been demonstrated that the copolymers of interest may exist in the mesomorphic state within a wide temperature interval. The ability of cyclolinear organosilicon copolymers to spread at the water/air interface and to form monolayers has been investigated. It has been shown that cyclosilane units that are structural isomers affect the pattern of surface pressure isotherms of the said copolymers.     

Polyelectrolyte Configuration of Low Molecular Weight Sodium Amylose Xanthate in Aqueous and Salt Solutions

The polyelectrolyte chain configuration of low molecular weight sodium amylose xanthate (NaAX) in aqueous and salt solutions has been studied by viscometry and light scattering. The viscometric results in aqueous solution have been found to be in accordance with the Fuoss's modified equation. The intrinsic viscosities of NaAX in salt solutions from 0.00125 to 0.25 M NaCl have been determined and the expansion factor a at each ionic strength has been determined. The dependence of a on ionic strength has been studied according to the theories of Hermans and Overbeek, Flory, etc. But though qualitative agreement between experimental and theoretical results has been found, quantitative agreement was far from expectations. The frictional coefficient per monomer unit | has been calculated from the relationship of Kirkwood and Riseman. The NaAX macromolecule has been found to have the polydispersed random coil chain configuration in 0.25 M NaCl. Some macromolecular configurational parameters such as effective bond length b, Kuhn-Kuhn equivalent chain length A_m, and steric factor α has been determined.     

Oxidation of crotyl alcohol by N-chloro-4-methylbenzene sulphonamide in acidic medium and in alkaline media in the presence of os(VIII) catalyst-a kinetic pathway

The kinetic pathway of oxidation of crotyl alcohol by sodium salt of N -chloro-4-methylbenzene sulphonamide (chloramine-T) in acidic and alkaline medium has been studied. The speciation of chloramine-T has been made to suggest a proper and reasonable reaction mechanism. The thermodynamic quantities such as activation energy and activation entropy are evaluated in acidic as well as in catalysed alkaline medium. An anticipated reaction mechanism has been suggested.     

Continuous and discontinuous phase transitions in ammonium halides

Raman spectra of NH₄Cl and NH₄Br have been recorded as functions of temperature and pressure. The λ-type phase transition in NH₄Cl has been studied as (i) a weakly first order. (ii) a tricritical and (iii) a second order transition. A strongly first order transition has been studied in NH₄Br. The analysis of the data has concentrated on the correlation of frequency shift with volume change across the phase change regions. This correlation has been established for the frequencies of the ν₂ and ν₅ Raman modes of NH₄Cl at zero pressure (1st order) 1.6 kbar (tricritical) and 2.8 kbar (2nd order), and the frequencies of the ν₅ Raman mode of NH₄Br at zero pressure (1st order). A single Y (mode Grünelsen parameter) has been shown to describe each frequency shift right through the phase change region once an order-disorder contribution has been introduced at and below the transition temperatures.     

Palladium η3-allyl complex with sorbic acid: Kinetics and mechanism of protodemetalation in aqueous solutions

The allyl complex di-μ-chloro-bis[(1,2,3-η)-1-carboxy-3-(1-hydroxyethyl)allyl]dipalladium (which is a hydroxyl-containing palladium η³-allyl complex based on sorbic acid) has been synthesized from trans,trans-2,4-hexadienic (sorbic) acid and Na₂PdCl₄ in an aqueous solution. The complex has been isolated from the reaction solution and has been characterized by IR, ¹H NMR, and ¹³C NMR spectroscopy. Its composition has been determined by elemental analysis. The protodemetalation kinetics of the complex in aqueous solutions has been studied. The rate of this reaction obeys a second-order equation, first-order with respect to each reactant. A reaction mechanism has been derived from protodemetalation kinetics and data characterizing the state of the reactants.     

The brilliant blue FCF ion-molecular forms in solutions according to the spectrophotometry data

The brilliant blue FCF acid–base properties in aqueous solutions have been studied and its ionization constants have been defined by tristimulus colorimetry and spectrophotometry methods. The scheme of the acid–base dye equilibrium has been proposed and a diagram of the distribution of its ionic-molecular forms has been built. It has been established that the dominant form of the dye was the electroneutral form, which molar absorptivity (ε₆₂₅ = 0.97 × 10⁵) increases with the increase of the dielectric permittivity of the solvent. It has been shown that the replacement of polar solvents by less polar ones is causing a bathochromic shift of the maximum absorption band of the dye, the value of which is correlated with the value of the Hansen parameter. Tautomerization constants have been defined in a number of solvents and associated with the value of the Dimroth-Reichardt parameter.