Gravimetric estimation of bismuth as bismuthyl dichromate

Summary Conditions are described for the quantitative precipitation of bismuthyl dichromate, (BiO)₂Cr₂O₇, and the suitability of this reaction for the gravimetric estimation of bismuth is shown. The use of arsenious oxide as a primary standard for the iodometric titration of excess chromate is emphasised.Sincere thanks of the authors are due to Prof. S. S. Joshi for research facilities and to Dr. G. S. Deshmukh for keen interest in the work.     

Determination of ascorbic acid by potassium iodate

Summary Results are given for a two stage oxidation in the ascorbic acid-KIO₃ reaction under controlled conditions of acidity. The first step corresponds to the Landolt reaction and the second end point is obtained by the classical Andrews method. The reproducibility and accuracy of the results calculated on the basis of the two successive end points constitute an interesting new feature of this redox reaction involving the use of KIO₃ as a primary standard for the determination of ascorbic acid.Our sincere thanks are due to Professor S. S. Joshi for kind interest in the work and to the National Institute of Sciences of India for award of a Research Fellowship to one of us (G. S. D.).     

Determination of bismuth by selenious acid

Summary Bismuth is shown to be precipitated quantitatively as bismuth selenite by boiling an almost neutral solution of bismuth nitrate and excess selenious acid. The excess H₂SeO₃ is determined iodometrically by standard thiosulphate or arsenious oxide solution. Alternatively, the precipitated selenite may be dried at 105–110° C and weighed as Bi₂(SeO₃)₃.Sincere thanks of the authors are due to Prof. S. S. Joshi for research facilities and to Dr. G. S. Deshmukh for keen interest in the work.     

Iodine monochloride end point in the oxidation of thiocyanate by permanganate. Determination of cerium

Summary A new volumetric method for cerium determination based on the quantitative reduction of Ce(SO₄)₂ by excess potassium thiocyanate and titration of the excess with standard KMnO₄ to the ICl end point has been described.Sincere thanks of the authors are due to Professor S. S. Joshi for facilities and kind interest in the work. The award of a U. P. Scientific Research Committee Scholarship to one of us (M.K.J.) is also gratefully acknowledged.     

Extrahierte Verbindungen von Gallium, Indium und Thallium in Verteilungssystemen mit Tributylphosphat, Cyclohexanon und Isobutylmethylketon

Zusammenfassung Das Verteilungsverhalten der Halogenide und Halogenometallate von Gallium, Indium und Thallium mit den drei Solventien (S) Tributylphosphat (TBP), Cyclohexanon (Cyclo) und Isobutylmethylketon (IBMK) wurde untersucht. Die extrahierten Verbindungen wurden nach der Geradenmethode nach Asmus, der logarithmischen Methode nach McKay, der Methode der kontinuierlichen Variation, durch Analyse der beiden Phasen und durch konduktometrische Extraktionstitration nachgewiesen. Identifiziert wurden folgende Verbindungen: [GaCl₄]^–·2 S, Ga-(SCN) ₃·3 TBP, [Ga(SCN)₄]^–·2 TBP, [InCl₄]^–·2 TBP, [InBr₄]^–·2TBP, [InBr₄]·x Cyclo, [InBr₄]^–·x IBMK, [InJ₄]^–·2 S, In(SCN)₃·3 TBP, [In(SCN)₄]^–·2 TBP, TlCl₃·1 TBP, [TlCl₄]^–·2 S, TlBr₃·1 TBP, [Tl-Br₄] ^–·2 S, TlJ₃·x TBP und [TlJ₄]^–·xS. Wegen der nicht eindeutig definierten Oxydationsstufe von Thalliumjodiden ergaben sich bei den Versuchen experimentelle Schwierigkeiten. Daher wurde in diesem System zusätzlich das radioaktive Isotop ²⁰⁴Thallium verwendet.

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Extracted compounds of gallium, indium and thallium in distribution systems with tributyl phosphate, cyclohexanone and isobutylmethylketone

The behaviour of distribution of the halides and halogenometallates of gallium, indium and thallium with the three solvents (S) tributylphosphate (TBP), cyclohexanone (Cyclo) and isobutylmethylketone (IBMK) are investigated. The extracted compounds are detected with the straight-line method of Asmus, the logarithmic method of McKay, the method of continuous variation, by analysis of the two phases, and with the conductometric extraction-titration. The following compounds were identified: [GaCl₄]^–·2S, Ga(SCN)₃·3TBP, [Ga(SCN)₄]^–·2TBP, [InCl₄]^–·2TBP, [InBr₄]^–·2TBP, [InBr₄]·x Cyclo, [InBr₄]^–·x IBMK, [InJ₄]^– ·2S, In(SCN)₃·3TBP, [In(SCN)₄]^–·2TBP, TlCl₃·1TBP, [TlCl₄]^–·2S, TlBr₃ ·1TBP, [TlBr₄]^–·2S, TlJ₃·x TBP and [TlJ₄]^–·x S. The not unequivocally defined stage of oxidation of thallium iodides resulted in experimental difficulties. Thus, in this system the radioactive isotope ²⁰⁴thallium was additionally used.

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Herrn Professor Dr. E. Asmus zum 60. Geburtstag gewidmet.

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Wie danken Herrn Priv.-Doz. Dr. H. Nickel für die freundliche Unterstützung bei den in der KFA Jülich durchgeführten radioaktiven Messungen.     

Conductometric estimation of thorium in dilute thorium chloride

Summary Conductometric titrations of thorium chloride against oxalic acid, ammonium oxalate and silver nitrate have been carried out at high dilutions (0.001, 0.0005 and 0.00033 M) of the chloride. Oxalic acid is found to be a suitable titrant for rapid estimation of thorium, the minimum error being +0.5%. The other titrants do not give good results. The titrations with ammonium oxalate indicate the step-wise ionisation of ThCl₄ into ThCl₂ ²⁺, ThCl³⁺ and Th⁴⁺. For mixtures of thorium chloride and cerous chloride, only the equivalence point corresponding to complete precipitation of both thorium and cerium is indicated.The authors express their sincere thanks to Prof. S. S.Joshi for his keen interest in this work and to Dr. G. S.Deshmukh for his advice and help in so many ways during the progress of these studies.     

Electrometric end points in the oxidation of thiocyanate by permanganate. Determination of cerium

Summary Oxidation of thiocyanate by standard permanganate using electrometric end points is shown to be quantitative in 1.5–2.5N HCl medium and in the presence of ICl as catalyst. A method of estimating cerium(IV), based upon its reduction to cerium(III) by excess KSCN and potentiometric titration of the excess against KMnO₄, is also described.Sincere thanks of the author are due to Prof. S. S. Joshi for research facilities.     

Eine neue Methode zur Darstellung von Thiozuckern

Zusammenfassung Durch direkte Einwirkung von H₂S in dimethylformamid aufPictetsches Anhydrid kann aus Glucose in fast quantitativer Ausbeute 1-Thio-d-glucopyranose erhalten werden.     

Determination of thiocyanate by potassium bromate

Summary Estimation of thiocyanate, based on its titration with standard KBrO₃ solution in presence of 1.5–3.0 N hydrochloric acid, is described. The end point is determined either potentiometrically or with methyl orange as indicator.Sincere thanks of the author are due to Professor S. S. Joshi for research facilities.     

Iodometric determination of potassium permanganate by arsenious oxide following iodide reduction in presence of borax-boric acid buffer and barium chloride

Summary An iodometric method for the determination of potassium permananate is described following its reduction to MnO₂ in presence of boraxboric acid buffer at PH 8–10 by iodide and titration of the liberated iodine with standard arsenious oxide solution. Excess BaCl₂ is added to coagulate the colloidal MnO₂ whose otherwise partial reduction by iodide is prevented thereby.Sincere thanks of the authors are due to Prof. S. S. Joshi, for his kind interest in the work.     

Natriumchlorit als Oxydationsmittel in der quantitativen analytischen Chemie

Zusammenfassung In der vorliegenden Arbeit werden einige Möglichkeiten der Verwendung von NaClO₂ als Oxydationsmittel für 8-Hydroxychinolin untersucht. Dabei ergaben sich vorteilhafte Verfahren zur Bestimmung von Elementen, welche als Oxinate fällbar sind.Als Beispiel ist eine indirekte Bestimmungsmethode von Molybdän in Molybdänitkonzentraten entwickelt worden, bei der die Rücktitration des Oxydationsmittelüberschusses mit jodometrischer oder potentiometrischer Endpunktsindikation erfolgt.V. Mitteilung: Spacu, P., M. Brezeanu, C. Gheorghiu u. E. Cristurean: Rev. Chim. A. S. I. T. 12, 723 (1961).     

Gene Cloning,Expression, and Characterization of a Family 51 α-<Emphasis Type="SmallCaps">l</Emphasis>-Arabinofuranosidase from <Emphasis Type="Italic">Streptomyces</Emphasis> sp. S9

An α-l-arabinofuranosidase gene, abf51S9, was cloned from Streptomyces sp. S9 and successfully expressed in Escherichia coli BL21 (DE3). The full-length gene consisted of 1,506 bp and encoded 501 amino acids with a calculated mass of 55.2 kDa. The deduced amino acid sequence was highly homologous with the α-l-arabinofuranosidases belonging to family 51 of the glycoside hydrolases. The recombinant protein was purified to electrophoretic homogeneity by Ni-NTA affinity chromatography and subsequently characterized. The optimal pH and temperature for the recombinant enzyme were 6.0 and 60∼65 °C, respectively. The enzyme showed a broad pH range of stability, retaining over 75% of the maximum activity at pH 5.0 to 11.0. The specific activity, K _m, and V _max with p-nitrophenyl-α-l-arabinofuranoside as substrate were 60.0 U mg⁻¹, 1.45 mM, and 221 μmol min⁻¹ mg⁻¹, respectively. Abf51S9 showed a mild but significant synergistic effect in combination with xylanase on the degradation of oat-spelt xylan and soluble wheat arabinoxylan substrates with a 1.19- and 1.21-fold increase in the amount of reducing sugar released, respectively. These favorable properties make Abf51S9 a good candidate in various industrial applications.     

Oxidation of thiocyanate by alkaline ferricyanide

Summary Oxidation of KSCN by alkaline K₃Fe(CN)₆ in presence of osmic acid has been studied quantitatively. The reaction proceeds at a measurable rate at ordinary temperature but is accelerated on refluxing the system on a water bath for a short time. The stoichiometry of the redox process suggests the formation of cyanate and sulphate as the products of oxidation. The quantity of thiocyanate is calculated by estimating the ferrocyanide formed and the ferricyanide consumed in terms of Ce(SO₄)₂ and Na₂S₂O₃ respectively. A kinetic study of the above reaction is under investigation.Sincere thanks of the author are due to Prof. S. S. Joshi for facilities and kind interest in the work. The award of a Scientific Man Power Committee Research Scholarship is also gratefully acknowledged.     

Β-d-Xylosidase from Selenomonas ruminantium: Catalyzed Reactions with Natural and Artificial Substrates

Catalytically efficient β-d-xylosidase from Selenomonas ruminantium (SXA) exhibits pK _as 5 and 7 (assigned to catalytic base, D14, and catalytic acid, E186) for k _cat/K _m with substrates 1,4-β-d-xylobiose (X2) and 1,4-β-d-xylotriose (X3). Catalytically inactive, dianionic SXA (D14⁻E186⁻) has threefold lower affinity than catalytically active, monoanionic SXA (D14⁻E186^H) for X2 and X3, whereas D14⁻E186⁻ has twofold higher affinity than D14⁻E186^H for 4-nitrophenyl-β-d-xylopyranoside (4NPX), and D14⁻E186⁻ has no affinity for 4-nitrophenyl-α-l-arabinofuranoside. Anomeric isomers, α-d-xylose and β-d-xylose, have similar affinity for SXA. 4-Nitrophenol competitively inhibits SXA-catalyzed hydrolysis of 4NPX. SXA steady-state kinetic parameters account for complete progress curves of SXA-catalyzed hydrolysis reactions. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Reduction of selenious acid by hydrazine sulphate. Volumetric determination of selenium

Summary A volumetric method of estimating selenium, depending upon the reduction of selenious acid by excess hydrazine sulphate solution and titration of the excess against KIO₃ to the iodine monochloride end point, has been described. Determination of tellurium on these lines is suggested.The author is indebted to Professor S. S.Joshi for facilities and kind interest in the work. The award of a Scientific Man Power Committee Research Fellowship is also gratefully acknowledged.     

Zur Kenntnis der Bitterstoffe der Colombowurzel V

Ohne ZusammenfassungIV. Mittlg. Mh. Chem.68 (1936) 313, bzw. S.-B. Akad. Wiss. Wien (IIb)145 (1936) 533.Die ersten Versuche in dieser Richtung sind bereits in den Diss. von HerrnIsemann (Feb. 1936) und Frl.Singer (Juli 1936) angeführt. Auch K.Feist u. Mitarb. (Liebigs Ann. Chem.523 [1936] 289) haben sich bereits mit der Methylierung ihres Carboxy-iso-V-columbins, das mit unserem Isocolumbin identisch und auch richtigerweise so zu benennen ist, beschäftigt und dabei einen Methyläther der Formel C₂₀H₂₁O₅· OCH₃ erhalten, über den aber in der angeführten Arbeit keine weiteren Versuche mitgeteilt werden.