Kinetics and mechanism of KBrO3 oxidation of D(+) xylose in acidic medium

KBr₃ oxidation of xylose, in presence of H₂SO₄, follows first order kinetics in [KBrO₃] and [xylose], and second order in [H₂SO₄]. The acid-catalyzed reaction gives aldonic acid as product. A mechanism consistent with temperature, solvent, higher acidity and salt effects has been proposed. Thermodynamic constants have been calculated.

---

KBrO₃ H₂SO₄ [KBrO₃] [] [H₂SO₄]. - . , , , . .

     

Isothermal titration calorimetry studies on the binding of DNA bases and PNA base monomers to gold nanoparticles

An isothermal titration calorimetric (ITC) investigation of the interaction of DNA bases and PNA base monomers with gold nanoparticles is described revealing a binding sequence in the order C > G > A > T. Direct measurement of the strength of interaction of ligands with nanogold by ITC has important implications in surface modification strategies for biomedical, catalysis, and nanoarchitecture applications.     

Influence of benzene moderator on the recoil collection of128I charged species during an (n, γ) process

Recoil reactions of¹²⁸I in liquid methyl iodide, ethyl iodide and n-butyl iodide target systems in the presence of benzene diluent have been studied by the charged plate technique. The investigations have been carried out over a wide range of diluent concentration. It has been observed that there are more collected recoil charged¹²⁸I species on the anode than on the cathode. The presence of benzene diluent in the target systems prior to neutron irradiation reduces the recoil collection on both electrodes.Preliminary findings were presented at the Annual Convention of Chemists, December 26–31, 1981, Madras.     

Kinetik der Oxidation von Diäthanolamin durch alkalisches Hexacyanoferrat(III)

The oxidation of diethanolamine by hexacyanoferrate(III) in alkaline medium has been found to be of first order with respect to diethanolamine, oxidant (at low concentrations) and hydroxyl ions; it tends to zero at higher concentrations of the oxidant. The effect of addition of sodium chloride, potassium sulphate and sodium acetate is positive, while that of hexacyanoferrate(II) ion is negligible. A mechanism involving the formation of an intermediate amine anion has been proposed.     

Adaptation of the bitartrate method for the estimation of potassium in sea bittern

Zusammenfassung Tetracyclin, Oxytetracyclin und Chlortetracyclin geben in einer salzsauren Lösung vom Ph 1 in Anwesenheit von 50 Vol-% Äthanol mit Ammoniummolybdat eine blaue Komplexverbindung, die zur colorimetrischen Bestimmung der Tetracycline im Konzentrationsbereich 0,025–0,5 mg/ml geeignet ist. Das Verfahren gestattet auch die Tetracyclinbestimmung in FermentansÄtzen.Wir danken Herrn Prof. L. Erdey für seine RatschlÄge, die er uns im Laufe der Untersuchungen gegeben hat.     

Structural,thermal, dielectric and optical behaviour investigations of water-free ZnO/lyotropic liquid crystal nanocolloids

ABSTRACT

Zinc oxide (ZnO) nanoparticles of spherical symmetry (average size of ≈ 20 nm) have been synthesised via a non-aqueous lyotropic liquid crystalline (LLC) templating process. Lyotropic liquid crystalline nanocolloids are prepared via dispersing 0.05, 0.1 and 0.5 wt.% ZnO nanoparticles in non-aqueous lyotropic phase. No structural phase change has been seen with the doping of nanoparticles as stable lamellar phases are observed in all the cases. Stability of the lamellar structure and orientation of the ZnO nanoparticles in the liquid crystalline matrix may be attributed to the interfacial surface charge interactions. A significant increase and pronounced dispersion in dielectric permittivity of the ZnO/LLC nanocolloids could be the result of parallel coupling among guest/host, higher dipole- moment of the ZnO nanoparticles and Maxwell-Wagner polarisation. The variation of relaxation parameters has also been discussed and correlated with the dielectric and structural parameters. ZnO/lyotropic nanocolloids devices exhibit dc conductivity of the order of 10^?5S/m owing to the increase in the number of ions (of the order of 10¹⁹m^?3) in the doped systems. Nanocolloids exhibits, the refractive index of range 1.40 to 1.45 and the wide bandgap of the range 4.1–4.5 eV.     

Tri-iso-amyl phosphate (TAP): An alternative extractant to tri-butyl phosphate (TBP) for reactor fuel reprocessing

Tri-iso-amyl phosphate (TAP), an indigenously prepared extractant was utilized for reactor fuel reprocessing and compared with tri-butyl phosphate (TBP) and tri-n-hexyl phosphate (THP). The potential of these extractants was found to be in the order TAP>THP>TBP by calculating the acid uptake value (K _H). The effect of various parameters such as solvent degradation due to acid hydrolysis, radiation effect, decontamination factor and phase separation were investigated and it was found that TAP was always a better extractant in comparison to THP and TBP. In addition to this, the extraction of fission product contaminants such as ¹⁴⁴Ce, ¹³⁷Cs, ¹⁰⁶Ru, ⁹⁵Zr was almost negligible, even at very high nitric acid concentrations in the aqueous phase, indicating the potential application of TAP in actinide partitioning. Sodium carbonate solution or acidified distilled water was a good strippant for U(VI), similarly, uranium(IV) nitrate stripped Pu(IV) from the organic phase.     

A modified ring electrographic method for the non-destructive analysis of metallic artefacts

Summary The utility of the ring electrographic technique as a non-destructive method of analysis of metallic artefacts of archeological importance is sufficiently accurate to give archeological meaningful results The electrographic sampling technique has been modified to give easier and more reliable sampling. The method is of particular value in the analysis of copper and silver coins.

---

Eine modifizierte elektrograpbische Ring-Methode zur Analyse metallischer Kunstgegenstände ohne deren Verletzung

Zusammenfassung Die Verwendbarkeit der elektrographischen Ring-Technik für die Analyse metallischer Gegenstände von archäologischem Interesse wurde erwiesen. Die elektrographische Probenahme wurde modifiziert. Das Verfahren ist für die Analyse von Kupfer- und Silbermünzen von besonderem Wert.

---

---

Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Amine elimination synthesis of a titanium(IV) N-heterocyclic carbene complex with short intramolecular Cl...C carbene contacts

The reaction of 1,3-dimesitylimidazolium chloride with Ti(NMe(2))(4) results in the 1,3-dimesitylimadazol-2-ylidene complex of Ti(NMe(2))(2)Cl(2)(3); the X-ray crystal structure of 3 evidences short intramolecular Cl...C(carbene) contacts.     

Kinetics and mechanism of palladium(II) catalysed oxidation of amines and aminoalcohols by N-bromosuccinimide in perchloric acid

Summary The kinetics of oxidation of amines (EtNH₂, Et₂NH, Et₃N) and aminoalcohols [H₂NCH₂CH₂OH, H₂N(CH₂)₃OH, (CH₂CH₂OH)₂NH, (CH₂CH₂OH)₃N] by N-bromosuccinimide (NBS) have been studied in aqueous HClO₄ with PdCl₂ as catalyst, and in the presence of Hg(OAc)₂ to ensure oxidation by pure NBS. The order of reaction with respect to NBS was unity, however, an increase in [NBS]₀ resulted in a decrease in the rate constant. The rate was directly proportional to [Pd^II] for the aminoalcohols while for EtNH₂ the rate was proportional to k + k[Pd^II] (where k and k are rate constants for the uncatalysed and catalysed paths, respectively). Retarding effects for HClO₄, succinimide, Cl^– and AcOH on the rate of oxidation were observed. The kinetic data support the formation of [Pd^II-A] and [Pd^II-(A)₂] complexes (where A represents amine or aminoalcohol). A mechanism, consistent with the observed kinetic data, is proposed.