Studies in the furan series

A study was made of certain transformations of the bicyclic compounds of the fur an series synthesized from 3,4-bis(chloromethyl)furan, N-butyl-4H, 6H-furo [3,4-c]pyrrole and 4H,6H-thieno[3,4-c]furan. On the basis of the same dichloride, 3,4-dimethyl furan and furan-3,4-dialdehyde were synthesized.For part XLVI, see [10].     

A new spot test for cerium(IV)

Summary A new colour reaction for the detection of cerram(IV) which can be carried out both in a test tube and on a spot plate has been described. The test solution is treated with methylene blue in nitric acid solution (11) to form a rose-red colour. This simple procedure has an advantage over the existing tests in that it is applicable in the presence of oxidising agents like chromium(VI), vanadium(V), nitrate, perchlorate and of coloured ions like copper(II), cobalt(II), nickel(II), chromium(III), iron(III), vanadium(IV), uranium(VI).

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Zusammenfassung Eine neue, sowohl in der Eprouvette wie auf der Tüpfelplatte ausführbare Farbreaktion zum Nachweis von Cer(IV) wurde angegeben. Die Probelösung wird mit salpetersaurer Methylenblaulösung behandelt und gibt eine rosarote Färbung. Die Reaktion hat gegenüber bekannten Tests den Vorteil, in Gegenwart von Oxydationsmitteln wie Cr(VI), V(V), NO₃ ^–, ClO₄ ^– bzw. in Anwesenheit gefärbter Ionen wie Cu(II), Co(II), Ni(II), Cr(III), Fe(III), V(IV) oder U(VI) anwendbar zu sein.

     

Ionenspezifische Glaselektroden

Zusammenfassung An Hand einer neueren erfolgversprechenden Theorie der Glaselektrode, der Phasengrenzpotentialtheorie, wird gezeigt, in welchem Maße gewisse Zusätze im Elektrodenglas die Eigenschaften desselben grundlegend verändern. Zusätze an dreiwertigen Metalloxiden, insbesondere Al₂O₃ und B₂O₃, ziehen ein spezifisches Ansprechvermögen auch auf andere einwertige Ionen nach sich (Beckman Cationic Electrode). Durch teilweisen Ersatz der Na₂O-Komponenten des Elektrodenglases durch Li₂O, wird ein extrem spezifisches Ansprechvermögen auf Na⁺-Ionen hervorgerufen (Beckman Sodium Electrode). Es werden Anwendungsbeispiele, Vorzüge und Grenzen dieser neuen Elektrodensorten erläutert.

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Summary A recent promising theory of the glass electrode, the theory of interface potential, is discussed and it is shown how far certain additives in the electrode glass can change its properties fundamentally. Addition of trivalent metal oxides (especially Al₂O₃ and B₂O₃) results in a specific response to other univalent ions, too (Beckman Cationic Electrode). Partial substitution of the Na₂O components of the glass by Li₂O causes an extremely specific response to Na⁺ ions (Beckman Sodium Electrode). Applications, advantages and limitations of these new dydes of electrodes are discussed.

     

Microdetermination of the keto group by the oxime method

Summary A method was developed for microdetermination of the carbonyl group in ketones, esters of keto acids and also in diketones, capable of giving dioximes, by oximation of them with hydroxylamine hydrochloride in the presence of triethanolamine.     

Application of capillary zone electrophoresis and reversed-phase high-performance liquid chromatography in the biopharmaceutical industry for the quantitative analysis of the monosaccharides released from a highly glycosylated therapeutic protein

Two assays for the quantitative determination of the neutral and amino-monosaccharides attached to a therapeutic glycoprotein were developed using capillary zone electrophoresis (CZE) and RP-HPLC. These assays meet the strict batch release requirements of the quality control in biopharmaceutical industry. The monosaccharides were released from the glycoprotein by hydrolysis with 2N trifluoroacetic acid. In the CZE assay the monosaccharides were reacetylated prior to derivatization with 8-aminopyrenesulfonic acid (APTS), reacetylation in the glycoprotein matrix was investigated in detail. The RP-HPLC method used pre-column derivatization with anthranilic acid in methanol-acetate-borate reaction medium; reacetylation was not necessary. However, epimerization of the different monosaccharides was observed and studied in detail. For the quantitative assay, separation of the amino-monosaccharide epimers had to be developed. The HPLC assay was validated.     

Semiclassical statistical mechanics of two-dimensional hard-body fluids

The problem of calculating the thermodynamic properties of two-dimensional semiclassical hard-body fluids is studied. Explicit expressions are given for the first-order quantum corrections to the free energy, equation of state, and virial coefficients. The numerical results are calculated for the planar hard dumbbell fluid. Significant features are the increase in quantum corrections with increasing eta and increasing L*=L/sigma(0).     

Effect of the homogeneity of the column set on the performance of a simulated moving bed unit. I. Theory

Although it is impossible to manufacture identical columns for use in a simulated moving bed (SMB) process, theoretical studies assume that all the columns in an SMB unit have identical characteristics. In practice, calculations in modeling and optimization studies are made with the average values of each column parameter set. In this report, the effects on SMB process performance caused by column-to-column fluctuations of the parameters are discussed. As a first step, we show how the differences in porosity of the columns may be taken into account with a revised set of separation conditions. Reductions in the purity of the extract and the raffinate streams are quantitatively related to the column-to-column fluctuations of the retention times of the two components arising from these porosity differences. For the sake of simplicity, the discussion first addresses the case of a four-column SMB operating under linear conditions. Then, the scope is extended to the cases of SMB units incorporating several columns in each section and to SMB units operating under nonlinear conditions.     

Separation and identification of organic and organometallic compounds by use of a liquid chromatography-particle beam-glow discharge mass spectrometry combination

Evaluation of the particle beam glow discharge mass spectrometry (PB-GDMS) system as a detector for liquid chromatography (LC) is described for the analysis of polycyclic aromatic hydrocarbons, steroids, selenoamino acids, and alkyllead compounds. A particle beam interface is used to introduce analyte species from the LC into a glow discharge source for subsequent vaporization and ionization. Mass spectra display classic EI fragmentation patterns for the organic compounds, as well as elemental and molecular information for the organometallic compounds. Chromatographic separations display good temporal correlation between UV and PB-GDMS detection modes. Detection limits for Pb in lead nitrate, triethyllead, and triphenyllead fall in the sub-ppb (ng) range.     

Perturbation approach for frequency shifts in IR spectra of molecular clusters

A second order perturbation approach for the evaluation of the splitting and shifting of the infrared vibrational bands of molecular clusters, based on early publications of Buckingham, is presented. The Hamiltonian of the system comprises harmonic- and anharmonic intramolecular vibration terms, as well as the intermolecular potential. The anharmonic contributions of the intramolecular force field and the intermolecular potential are treated as a perturbation. In order to extend the applicability of the approach to homogeneous molecular clusters, the formalism of degenerate perturbation theory is employed. The new approach is applied to methanol clusters from dimer to hexamer for calculating the frequency shifts of the OH stretching mode (ω₁=3681.5 cm^?1), the CH₃ rocking mode (ω₇=1074.5 cm^?1), and the CO stretching mode (ω₈=1033.5 cm^?1). The numerical results compare favourably with experimental and previous theoretical data (except for ω₁), but with a tendency to overestimate the shifts.     

Oxidative addition of some geminal halonitroalkanes to iridium(I) and platinum(0) compounds

Oxidative addition of 1-chloro-1-nitroethane to trans-IrCl(CO)-[P(CH₃)₂C₆H₅]₂ followed by treatment of the initial product with pyridine yields a new iridium(III) complex IrCl(py)[COC(NO₂)CH₃][P(CH₃)₂C₆H₅]₂, whose structure has been confirmed by X-rays crystallography. Two intermediate products have been observed by NMR spectroscopy; their structures have been tentatively assigned. The reaction of the corresponding bromine derivatives yields two isomers of the composition IrBr₂(CO)[CH(NO₂)CH₃][P(CH₃)₂C₆H₅]₂, and these are not affected by pyridine. The reaction of 1-chloro-1-nitroethane with Pt[P(C₆H₅)₃]₄ takes a completely different course in that yields nitrorethane and cis-PtCl₂[P(C₆H₅)₃]₂ as the main products, with no detectable formation of the products of oxidation addition. A brief mechanistic investigation points towards the participation of radicals and radical anions as transient intermediates and a mechanism is proposed which explains most of the experimental results.