Electrochemical studies on the composition,stabilities and thermodynamics of Zn+2, Cd+2 and Pb+2 complexes with methylene bis thio acetic acid

Potentiometric and conductometric studies on the zinc, cadmium, lead—methylene bis thio acetic acid system in aqueous media reveal the formation of 1:1 and 1:2 (M:L) complexes in thepH range 3.4–5.1. Their stability constants have been determined at 20°, 30° and 40 °C by applyingCalvin andMelchior's extension ofBjerrum's method. The overall changes in thermodynamic function H, G and S accompanying complexation have been evaluated at 30 °C.

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Elektrochemische Untersuchungen über Zusammensetzung, Stabilität und Thermodynamik von Zn(II)-, Cd(II)- und Pb(II)-Komplexen mit Methylen-bisthioessigsäure

Zusammenfassung Potentiometrische und konduktometrische Untersuchungen an Zink-, Cadmium- und Blei-Methylen-bis-thioessigsäure-Systemen in wäßrigem Medium zeigten die Bildung von 1:1 und 1:2 (M:L)-Komplexen impH-Bereich 3,4–5,1. Die Stabilitätskonstanten wurden bei 20°, 30° und 40 °C mittels derCalvin-Melchior-Methode (erweiterteBjerrum-Methode) bestimmt. Die thermodynamischen Parameter H, G und S der Komplexierung wurden für 30 °C ermittelt.

     

Molecular vibrations,electronic structure and conformation of diprotonated thiocarbohydrazide

The infrared spectra of diprotonated species of thiocarbohydrazide and its perdeuterated derivative have been examined in the crystalline state. A complete vibrational assignment with a full normal coordinate treatment based on a Urey—Bradley type intramolecular potential Function supplemented with a valence force function for the out of plane and torsional modes is proposed and the origin of the amide II band splittings is explained. A CNDO/2 study of diprotonated thiocarbohydrazide and its neutral molecule is undertaken and the changes in the molecular electronic structures and conformations consequent to protonation are determined and briefly discussed. The magnitude of the N—N⁺H₃ torsional barrier is estimated to be 21 kJ mol^? (5.0 kcal mol^?1) whereas the barrier for the C—N group is found to be 92 kJ mol^?1 (22.0 kcal mol^?1).     

An infrared spectroscopic investigation on N-methyl-1,3-thiazolidine-2-thione and -2-selone

An infrared investigation cm N-methyl-1,3-thiazolidine-2-thione and -2-selone in the range 4000-200 cm^?1 is reported. The v CS and v CSe vibrations give contributions to the absorptions around 1000 cm^?1 and below 600 cm^?1. The assignments are supported by comparison of their ir spectra with those of S- and Se-methiodides. The π-bond orders of the thio- and seleno-ketonic links in these compounds are higher than those found for 1,3-imidazolidine-2-thione and -2-selone.     

Catalytic Transfer Hydrogenation,A Chemo-Selective Reduction of Isoflavones to Isoflavanones

Isoflavones can be selectively reduced by catalytic transfer hydrogenation employing formic acid, ammonium formate or triethylammonium formate in the presence of 10% Pd/C. The reaction is simple, clean and gives fair yields of isoflavanones.     

Generation of strong, homochiral bases by electrochemical reduction of phenazine derivatives

Electrochemical reduction of enantiomerically pure amino- and alkoxy-phenazine derivatives forms strongly basic radical anions which give asymmetric induction in the conversion of 3,4-epoxytetrahydrothiophene-1,1-dioxide into the allylic ester with facile regeneration of the phenazine.     

Highly conductive soluble terpolymers of aniline,toluidine, and o‐aminobenzoic acid/m‐aminobenzenesulfonic acid

Two series of terpolymers, one of o‐/m‐toluidine and aniline with o‐aminobenzoic acid and the other of o‐/m‐toluidine and aniline with m‐aminobenzenesulfonic acid, have been synthesized by oxidative polymerization via an emulsion method with ammonium persulfate as the oxidant and HCl as the external dopant. The terpolymers exhibit excellent solubility and retain the high conductivity (∼1 S cm⁻¹) characteristic of the unsubstituted homopolymer, polyaniline. The terpolymers also possess higher thermal stability than polyaniline. This can be attributed to the presence of internal doping groups and substituents, which introduce flexibility to the otherwise rigid polyaniline backbone. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3040–3048, 2005     

Optimal execution with weighted impact functions: a quadratic programming approach

In this paper, we develop optimal trading strategies for a risk averse investor by minimizing the expected cost and the risk of execution. Here we consider a law of motion for price which uses a convex combination of temporary and permanent market impact. In the special case of unconstrained problem for a risk neutral investor, we obtain a closed form solution for optimal trading strategies by using dynamic programming. For a general problem, we use a quadratic programming approach to get approximate dynamic optimal trading strategies. Further, numerical examples of optimal execution strategies are provided for illustration purposes.     

Facile and efficient synthesis of chiral sulfoxide esters: Versatile tool in asymmetric synthesis

Facile and efficient synthesis of sulfoxide esters using menthols as chiral auxiliary is described. Phenylthio/benzylthio/naphthylthioacetic esters act as an efficient substrate for chiral sulfoxides via oxidation in one step. The structural and stereochemical aspects of target product were established on the basis of various spectroscopic studies, namely FT-IR, NMR (¹H NMR and ¹³C NMR) and elemental analysis. This method is simple, fast, convenient and very efficient.     

Inertial clustering of particles in high-Reynolds-number turbulence

We report experimental evidence of spatial clustering of dense particles in homogenous, isotropic turbulence at high Reynolds numbers. The dissipation-scale clustering becomes stronger as the Stokes number increases and is found to exhibit similarity with respect to the droplet Stokes number over a range of experimental conditions (particle diameter and turbulent energy dissipation rate). These findings are in qualitative agreement with recent theoretical and computational studies of inertial particle clustering in turbulence. Because of the large Reynolds numbers a broad scaling range of particle clustering due to turbulent mixing is present, and the inertial clustering can clearly be distinguished from that due to mixing of fluid particles.