Oximidobenzotetronic acid as a reagent for the separation and gravimetric determination of palladium and cobalt

Oximidobenzotetronic acid is recommended for the separation and gravimetric determination of palladium and cobalt An ethanolic solution of the reagent quantitatively precipitates palladium(II) from solutions which are 0.75 N in acid up to pH 5.1, the complex is weighed as Pd(C₉H₅NO₄)₂. Cobalt(II) can be determined in the filtrate after the precipitation of palladium. With 0.5 N acid solutions, no interference was found from Pt(IV), Ir(IV), Rh(III), Ru(III), Os(IV), Au(III), Ag(I), Cu(II), Fe(III), Ni(II), Hg(II). Pb(II), Bi(III), Cd(II), As(V), Se(VI), Te(IV), Mo(VI), Sb(III), Al(III), Cr(III), Zn(II), Ti(IV), Zr(IV). acetate, oxalate, citrate, tartrate, phosphate and fluoride.     

Gravimetric determination of molybdenum and tungsten using pyridoin as a reagent

Summary Pyridoin has been used as a reagent for the gravimetric determination of molybdenum and tungsten. The reagent quantitatively precipitates molybdenum from ammonium molybdate solution at p_H 2.0–9.5 and tungsten from sodium tungstate solution at p_H 2.0–4.5. The precipitate in each case is ignited to the oxide and weighed.

---

Zusammenfassung Zur gravimetrischen Bestimmung von Molybdän und Wolfram wird Pyridoin als Reagens empfohlen. Molybdän wurde aus Ammoniummolybdatlösung bei p_H 2,0–9,5 quantitativ ausgefällt, Wolfram aus Natriumwolframatlösung bei p_H 2,0–4,5. Die Niederschläge wurden jeweils zum Oxid verglüht und dieses ausgewogen.

     

Cyclodesulfurization of Substituted Thiosemicarbazides into 1,3,4-Oxadiazoles via Hydrazonoyl Chlorides

Abstract

The reaction of thiosemicarbazides 1a–h with hydrazonoyl chlorides 2a–g at ambient temperature, in the presence of triethylamine yielded, in each case, two products. The structure of these compounds was confirmed as 1,3,4-oxadiazoles 14a–h and hydrazonothioates 15a–g. The structure of 15b was confirmed through single crystal X-ray diffraction. A mechanism was proposed for this cyclodesulfurization reaction.     

Miscibility and Thermal Behavior of Pullulan/Polyacrylamide Blends

Blends of Pullulan (PU) and Polyacrylamide (PAM) having biomedical applications were prepared and characterized in order to evaluate the miscibility of natural component with the synthetic one. Blends with different composition ratios were prepared using water as common solvent. Viscosity, ultrasonic velocity and density were measured at 30 and 40°C. Furthermore, the blend films were prepared by a solution casting method and analyzed by DSC, FTIR and TGA methods. Results of ultrasonic and density methods revealed the semi-miscibility of the blend. Using viscosity data, interaction parameters (Chee's ‘μ’ and Sun's ‘α’) were computed. The values confirmed that the blend is miscible when the Pullulan content is less than 20% in the blend. Change in temperature had no effect on the miscibility nature of the blends. Intermolecular interactions of hydrogen bonding type were confirmed by DSC and FTIR methods. Thermal behavior of blends was investigated using TGA method.     

Catalytic activity of CeO2 and Pr2O3 for the liquid-phase benzylation of o-xylene to 3,4 – dimethyldiphenylmethane

The liquid phase benzylation of o-xylene with benzyl chloride over rare earth oxide catalysts like CeO₂ and Pr₂O₃ was studied in a batch reactor at atmospheric pressure and 363 K. Surface area, pore volume, DTA, acid strength distribution on the catalyst surface and optimum temperature of the catalyst are reported.     

Palladium–Schiff base–triphenylphosphine catalyzed oxidation of alcohols

Novel palladium(II)‐N‐(2‐pyridyl)‐N′‐(5‐R‐salicylidene) hydrazine triphenylphosphine complexes were synthesized and characterized by UV, IR, ¹H NMR and ³¹P NMR spectral analysis, C, H, N analysis and magnetic susceptibility measurements. The complexes were effective in the catalytic oxidation of primary and secondary alcohols in presence of N‐methyl‐morpholine‐N‐oxide as oxidant. The oxidation reactions were carried out in dichloromethane. A mechanistic study of the above reactions has been proposed. Copyright © 2010 John Wiley & Sons, Ltd.     

Limitations in the use of horseradish peroxidase as an enyzme probe in the development of a homogeneous immunoassay for aflatoxin B1

Horseradish peroxidase (HRPO) was used as a probe to quantitate aflatoxin B₁ by a homogeneous immunoassay. The conjugation of AFB₁ to HRPO resulted in 54% loss of enyzme activity. In the presence of AFB₁ specific antibodies, the HRPO-AFB₁ conjugate showed reversal of its lost enzyme activity by 12%. This positive modulatory effect of antibody on the enzyme activity was used as an analytical tool to quantitate AFB₁. The homogeneous assay carried out with free AFB₁ and HRPO-AFB₁ conjugate in the presence of antibodies indicated poor linearity as compared to the heterogeneous assay. It was observed that the number of HRPO-lysine residues involved in AFB₁ conjugation were 6–8. The low level of modulation of enzyme activity by antibody with respect to HRPO-AFB₁ conjugate, could possibly be attributed to the limited number of lysine residues in the HRPO molecule and its proximity to the active site of the enzyme. Thus, HRPO was found to be limiting as an enzyme with respect to the homogeneous enzyme immunoassay for AFB₁ analysis. The antibodies raised were specific for AFB₁, and showed excellent linearity even at high dilution for the detection of AFB₁ by ELISA indicating that antibodies per se were not the limiting factor.     

X-ray K-absorption spectrum of yttrium in some yttrium pyrochlores

The X-ray K-absorption edge of yttrium in some pyrochlores of the type YLnFeSbO₇ have been investigated using a 400 mm bent crystal spectrograph. The position of the principal absorption edge was found to have shifted towards the low energy side when Ln was changed from lanthanum through erbium. On the basis of the extended absorption fine structure estimates about the bond lengths have been made using the Lytle's and Levy's techniques.     

Aziridine carboxylate from D-glucose: synthesis of polyhydroxylated piperidine, pyrrolidine alkaloids and study of their glycosidase inhibition

The D-glucose derived aziridine carboxylate 5 was obtained from (E)-ethyl-6-bromo-1,2-O-isopropylidene-3-O-benzyl-5-deoxy-alpha-D-xylo-5-eno-heptofuranuronate 4 through conjugate addition of benzylamine and in situ intramolecular nucleophilic expulsion of bromine. The regioselective aziridine ring-opening, using water as a nucleophile, resulted in the alpha-hydroxy-beta-aminoester 6, which was exploited in the synthesis of six and five membered azasugars 1b/1c and 2b/2c, respectively. The glycosidase inhibitory activity of the title compounds was evaluated.     

Study of Zgamma events and limits on anomalous ZZgamma and Zgammagamma couplings in pp collisions at square root s = 1.96 TeV

We present a measurement of the Zgamma production cross section and limits on anomalous ZZgamma and Zgammagamma couplings for form-factor scales of lambda = 750 and 1000 GeV. The measurement is based on 138 (152) candidates in the eegamma (mumugamma) final state using 320(290) pb(-1) of pp(-1) collisions at square root of s = 1.96 TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are /h(10,30)Z/ < 0.23, /h(20,40)Z/ < 0.020, /h(10,30)gamma/ < 0.23, and /h(20,40)gamma/ < 0.019 for lambda = 1000 GeV.