Solubility studies in formamide: II. Solubility product of silver iodate and standard electrode potential of silver—silver iodate electrode in formamide

The solubility and solubility product of silver iodate in formamide in sodium perchlorate solutions have been determined at 25, 30 and 35°C. The solubilities in pure formamide are found to be 2.169 × 10^?4, 2.488 × 10^?4, and 2.943 × 10^?4 mole I^?1, respectively, at these temperatures, and the corresponding solubility products are 4.609 × 10^?8, 6.053 × 10^?8, and 8.448 × 10^?8 mole² 1^?2. The standard potential of the Ag_(s)/AgIO_3(s)/IO₃^? electrode has been calculated and found to be 0.2562 V at 25°C. The mean activity coefficients of silver iodate at various rounded molarities of sodium perchlorate solutions, and the standard thermodynamic quantities for the process AgIO_3(s)åAg⁺ (solvated) + IO₃^? (solvated) have been calculated at these three temperatures.     

Mechanistic Study of the Reactions of l-ascorbic Acid and Oxalic Acid with an Octahedral Manganese(IV) Complex of 1,8-bis(2-hydroxybenzamido)-3,6-diazaoctane

The Mn^IV complex of 1,8-bis(2-hydroxybenzamido)-3,6-diazaoctane (Mn^IVL) with phenolate-amido-amine coordination is reduced by l-ascorbic acid and oxalic acid obeying overall 1:1 stoichiometry. The reactions are biphasic and Mn^IIIL⁻ is the reactive intermediate. The product of oxidation of ascorbic acid (H₂Asc) is dehydroascorbic acid and that of oxalic acid (H₂OX) is CO₂, while Mn^II is the end product from Mn^IV. Both Mn^IVL and Mn^IIIL⁻ form outer sphere adducts with H₂Asc and H₂OX with high values of equilibrium constants of formation (Q>10² dm³ mol⁻¹, I = 0.5 mol dm⁻³, 25.8 °C, 1.5% v/v MeOH+H₂O). The adduct formation is diffusion controlled and is attributed to hydrogen bonding interactions between the reactants. The rate constants for the electron transfer in (Mn^IV/^IIIL, H₂A), (Mn^IV/^IIIL, HA⁻) (H₂A = H₂Asc, H₂OX) and for (Mn^IVL, H₂Asc)+H₂Asc, (Mn^IIIL⁻, HAsc⁻)+HAsc⁻ are reported. There was no evidence of direct coordination of the reductants to the Mn^IV/III center indicating an outer sphere (ET) mechanism.     

Synthesis of a novel, highly symmetric bis-oxa-bridged compound

A highly oxygenated, novel pentacyclic bis-oxa-bridged compound 8 was synthesized with remarkable efficiency starting from readily available tetrachloro-5,5-dimethoxyclopentadiene and 1,4-cyclohexadiene in three steps. The ruthenium-catalyzed oxidation of 2:1 bis-adduct 1 followed by a one-pot transformation of the resulting bis-alpha-diketone 3 furnished (after esterification) the title compound in an overall yield of 29.1%. The versatility of this simple method was further demonstrated with other norbornyl alpha-diketones to obtain the corresponding strained oxa-bridged derivatives.     

Thermal degradation studies of substituted conducting polyanilines

The synthesis of conducting polymers based on m-nitroaniline, m-chloroaniline and m-aminophenol by aniline initiated ammonium peroxydisulfate oxidation, has been attempted. The IR spectra of the polymers have been studied. Thermogravimetric analysis of the conducting polymers has been followed using a computer analysis method LOTUS PACKAGE, developed by us for assigning the degradation mechanism. A number of equations have been used to evaluate the kinetic parameters. The mechanism of degradation of the conducting polymers has been explained on the basis of their kinetic parameters.     

The(q\bar q) - pion and its decay constant in a chiral potential modeland its decay constant in a chiral potential model

Pion mass and its decay constant have been studied in a chiral symmetric potential model of independent quarks. The non-perturbative multi-gluon interaction which is responsible for quark confinement in a hadron is phenomenologically represented here by an effective potentialU(r) = 1/2(1 +γ ⁰)(ar ² +V ₀). The residual interactions due to quark-pion coupling arising out of the chiral symmetry preservation and that due to quark-gluon coupling arising out of single-gluon exchange are treated as low order perturbations. The centre of mass correction is also taken into account appropriately. This leads to the mass in consistency with that of the PCAC-pion and the pion decay constant in reasonable agreement with experiment.     

Hydrotalcite catalysis in ionic liquid medium: a recyclable reaction system for heterogeneous Knoevenagel and nitroaldol condensation

Knoevenagel condensation proceeds efficiently in recyclable [bmim]PF₆ and [bmim]BF₄ without any catalyst, and hydrotalcites in ionic liquid serve as a safe and recyclable reaction system for both Knoevenagel as well as nitroaldol condensations.     

Complexes of copper(II) with 4-methylimidazole

Summary The ligand, 4-methylimidazole L, reacts with Copper(II) to yield hexacoordinated and tetragonal complexes, CuL₄X₂ (X = Cl, Br, NO₃, ClO₄, NCS or 0.5 SO₄) and CuL₆(BF₄)₂; and tetracoordinated square-planar complexes, CuL₂(N₃)₂, (CuL₄)H9Cl₄) and (Me₄N)(CuLCl₃). The complexes obtained were characterized on the basis of analytical data, i.r. and electronic spectra, conductance and magnetic susceptibility measurements. T.g.a, d.t.g and d.t.a studies have been made for some of the complexes which were found to decompose with loss of imidazole ligand. The stoichiometry of the thermal decompositions was determined.     

Preparation and deployment of indigenous 125I-seeds for the treatment of prostate cancer: Dawn of prostate brachytherapy in India

‘Permanent seed implantation’ using ¹²⁵I- seeds has emerged as an effective treatment modality for management of prostate cancer. An indigenous technology for the production of ¹²⁵I brachytherapy sources (‘BARC ¹²⁵I Ocu-Prosta seed’) has been developed. In this current work, we describe an overview of our experience on large scale production of ¹²⁵I brachytherapy sources, their quality assessment, in vivo bio-evaluation and initial experience on their journey from bench to bed-side for the treatment of prostate cancer.     

Cr(VI) oxidation using cetylpicolinium dichromate: Kinetics of oxidation of benzaldehydes with a green protocol

Oxidation kinetics of benzaldehyde and some of its ortho- and para-monosubstituted derivatives have been studied using cetylpicolinium dichromates, a class of novel phase transfer oxidants, in dichloromethane medium. The rate of reaction is first order with respect to oxidant and fractional order with respect to the substrates. The Michaelis–Menten type oxidation was observed with respect to the substrates. Benzaldehydes are found to be oxidized to their corresponding acids. The mechanism of oxidation reaction has been suggested based on the solvent isotope effect, Hammett plot, and thermodynamic study. The solvent isotope effect (k_CHCl3/k_CDCl3 = 1.57) indicates the involvement of hydrogen exchange with the medium during oxidation reactions. A strong influence of specific solute–solvent interactions on the rate of the reaction is observed. Both the electron-withdrawing and electron-releasing substituents on the substrates accelerate the rate of reaction.     

Well‐Defined N‐Heterocyclic Carbene‐Palladium Complexes as Efficient Catalysts for Domino Sonogashira Coupling/Cyclization Reaction and C‐H bond Arylation of Benzothiazole

Well‐defined and air‐stable PEPPSI (Pyridine Enhanced Precatalyst Preparation Stabilization and Initiation) themed palladium bis‐N‐heterocyclic carbene complexes have been developed for the domino Sonogashira coupling/cyclization reaction of 2‐iodophenol with a variety of terminal alkynes and C‐H bond arylation of benzothiazole with aryl iodides. The PEPPSI themed palladium complexes, 2a and 2b were synthesized in good yields from the reaction of corresponding imidazolium salts with PdCl₂ and K₂CO₃ in pyridine. The new air‐stable palladium‐NHC complexes were characterized by NMR spectroscopy, X‐ray crystallography, elemental analysis, and mass spectroscopy studies. The PEPPSI themed palladium(II) bis‐N‐heterocyclic carbene complexes 2a and 2b exhibited excellent catalytic activities for domino Sonogashira coupling/cyclization reaction of 2‐iodophenol with terminal alkynes yielding benzofuran derivatives. In addition, the palladium complexes, 2a and 2b successfully catalyzed the direct C‐H bond arylation of benzothiazole with aryl iodides as coupling partners in presence of CuI as co‐catalyst.