SYNTHESIS, CHARACTERIZATION AND CATALYTIC ACTIVITY OF N,N‘-BIS(3-ALLYL SALICYLIDENE)ETHYLENEDIAMINE COBALT(II) SCHIFF BASE COMPLEX ANCHORED ON A NEW POLYMER SUPPORT

A new chelating polymer support has been prepared by suspension copolymeriz a tion of synthesized N,N‘-bis(3-allyl salicylidene)ethylenediamine monomer Schiff base (N,N‘-BSEDA) with styrene (St) and divinylbenzene (DVB) using azobisisobutyronitrile (AIBN) as initiator in the presence of poly(vinyl alcohol). The content and complexation ability of monomer Schiff base (N,N‘-BSEDA) for cobalt(II) ions in prepared crosslinked polymer beads have shown dependence on the amount of DVB used in reaction mixture. The amount of monomer Schiff base (N,N‘-BSEDA) in crosslinked beads showed a substantial decreasing trend at high concentration of DVB in the reaction mixture (＞ 1.5 mol dm-3), hence the efficiency of complexation (EC%) and cobalt(II) ion loading (EL%) of polymer beads showed a decreasing trend. The structure of monomer Schiff base (N,N‘-BSEDA) and its cobalt(II) complex on polymer support was elucidated by IR, UV and magnetic measurements. The catalytic activity of polymer bound cobalt(Ⅱ) Schiff base complex was evaluated by analyzing kinetic data of decomposition of hydrogen peroxide in the presence of either supported cobalt (II) complex or free cobalt(II) complex. The activation energy for the decomposition of hydrogen peroxide by polymer supported cobalt(II)complex was found to be low (33.37 kJ mol-l) in comparison with unsupported cobalt(II) complex (56.35 kJ mol-1). On the basis of experimental observations, reaction steps are proposed and a suitable rate expression derived.     

Forced Degradation Study on Gliclazide and Application of Validated Stability-Indicating HPLC-UV Method in Stability Testing of Gliclazide Tablets

Forced degradation study on gliclazide was conducted under the conditions of hydrolysis, oxidation, dry heat and photolysis and an isocratic stability-indicating HPLC-UV method was developed and validated. All the seven degradation products (I–VII) formed under different conditions were optimally resolved on a C₁₈ column with mobile phase composed of 40% acetonitrile and 60% ammonium acetate solution (0.025 M, pH 3.5) at a flow rate of 0.25 mL min^?1 using 235 nm as detection wavelength. The method was linear between 5–500 μg mL^?1 drug concentrations. The %RSD of intra- and inter-day precision studies was <1 and <2% respectively. Excellent recoveries (99.81–100.97%) proved the method sufficiently accurate. Each peak resolved always with a resolution of >1.90 indicating the method to be rugged enough. The method was used to study the drug degradation behaviour under the forced conditions. Four degradation products (I–IV) were formed in 0.1 N HCl and water whereas only I and III were formed in 3% H₂O₂. Two new products V and VI in addition to I, III and IV were formed in 0.1 N NaOH. The drug was stable to thermal and photolytic decomposition. The degradation behaviour in water and 0.1 N NaOH was similar under dark and light conditions but a new product VII was formed in 0.01 N HCl in light. In general, the rate of degradation was accelerated by the light. The method was applied successfully in stability testing of gliclazide tablets.     

SYNTHESIS, CHARACTERIZATION AND CATALYTIC ACTIVITY OF N,N''''-BIS(3-ALLYL SALICYLIDENE)ETHYLENEDIAMINE COBALT(Ⅱ) SCHIFF BASE COMPLEX ANCHORED ON A NEW POLYMER SUPPORT

INTRODUCTIONAlthough homogeneous catalysts have higher selectivity and act under mild experimental conditions in variousreactions they have problems of separation and recovery from reaction products. Hence current research activitiesare aimed at developing catalysts of coordination compounds anchored on suitable supports[1,2]. This techniqueof immobilization of catalyst on an inert support increases the catalytic activity, selectivity, efficiency[3],operational flexibility and stability. …     

Kinetics and mechanism of bromamine-T oxidation of some cyclic ketones in acidic media

Kinetics of the oxidation cyclopentanone and cyclohexanone by bromamine-T(BAT) have been reported in perchloric acid media. A zero order dependence to BAT and first order dependence on both ketones and hydrogen ion concentrations have been observed. Observed stoichiometry, zero effects of ionic strength of the medium and p-toluenesulphonamide (TSA) and a negative dielectric effect point to a mechanism involving acid catalysed enolisation of ketones in the slow and rate determining step, followed by its subsequent fast interaction with BAT giving corresponding 1,2-diketones as final products. A solvent isotope effect (kD₂O/kH₂O = 2.0–2.2 (35°), 2.1–2.3 (40°) and 2.2–2.4 (35°), 2.3–2.5 (40°) for cyclopentanone and cyclohexanone, respectively) has been observed. Various thermodynamic parameters have been computed.     

Oxozirconium(IV) alkoxides

Oxozirconium(IV) alkoxides of the type ZrO(OR)₂·ROH and ZrOCl(OR)·2 ROH, where R is methyl, ethyl, and isopropyl, and ZrO(OCMe ₃)₂·0.5Me ₃COH and ZrOCl(OCMe ₃)·1.5Me ₃COH have been prepared by the reaction of dichloroxozirconium(IV)-2-acetic acid with corresponding alcohols in the presence of appropriate amounts of piperidine. The alkoxides have been isolated and characterised through infrared, thermal and conductance studies.     

Spectral and magnetic studies on normal cobalt(II) planar and cobalt(III) octahedral, spin-crossover cobalt(III) octahedral and planar-tetrahedral cobalt(II) carbodithioates

Five cobalt(II) complexes, a normal complex Co(4-PPipzcdt)₂ (4-PPipzcdt = 4-phenylpiperazine-1-carbodithioate), and four zwitterionic complexes, Co(4-PPipzcdtH)₂X₂ and Co(4-MPipzcdtH)₂X₂ (X = Cl, Br; 4-PPipzcdtH = 4-phenylpiperazine-1-carbodithioic acid, 4-MPipzcdtH = 4-methylpiperazine-1-carbodithioic acid), have been synthesized. Normal cobalt(III) complexes of the type Co(4-MPipzcdt)₃ and Co₂ {2-MPipz(cdt)₂}₃ (2-MPipz(cdt)₂ = 2-methylpiperazine-1,4-dicarbodithioate) and two zwitterionic cobalt(III) complexes of the type Co(4-MPipzcdtH)₃X₃ (X = Cl, Br) have also been obtained. In addition to the room temperature IR and electronic spectra and magnetic susceptibility studies, all the complexes, except the normal Co(4-MPipzcdt)₃ and Co(4-PPipzcdt)₂ and zwitterionic Co(4-MPipzcdtH)₃Cl₃, have been investigated by variable-temperature magnetic susceptibility measurements. The results of the variable-temperature magnetic susceptibility studies suggest that two cobalt(II) carbodithioates exhibit a square planar-tetrahedral equilibrium, while two cobalt(III) octahedral carbodithioates show a spin-crossover phenomenon.     

Determination of uranium isotopes in urine samples from radiation workers using 232U tracer, anion-exchange resin and alpha-spectrometry

Bioassay technique is used for the estimation of actinides present in the body based on the excretion rate of body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha-spectrometry requires pre-concentration of large volumes of urine. This paper deals with standardization of analytical method for the determination of U-isotopes in urine samples using anion-exchange resin and ²³²U tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of uranium along with calcium phosphate. Separation of U was carried out by Amberlite, IRA-400, anion-exchange resin. U-fraction was electrodeposited and activity estimated using tracer recovery by alpha-spectrometer. Eight routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range of 51% to 67% with a mean and standard deviation of 60% and 5.4%, respectively.     

Die Synthese von 2-Amino-5-fluorthiophenol und seine Umwandlung in Phenothiazine und deren Sulfone

Zusammenfassung Es wurde versucht, 2-Amino-5-fluorthiophenol durch hydrolytische Spaltung von 2-Amino-6-fluorbenzothiatol darzustellen. Kondensation mit reaktiven Halogennitrobenzolen gab 1-Nitro-phenothiazine, deren Oxidation zu Phenothiazinsulfonen detailliert untersucht wurde.

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Synthesis of 2-amino-5-fluorobenzenethiol and its conversion into phenothiazines and their sulphones

Attempts have been made to synthesise 2-amino-5-fluorobenzenethiol through hydrolytic cleavage of 2-amino-6-fluorobenzothiazole. It has been converted into substituted 1-nitro phenothiazines by condensation with reactive halogenonitrobenzenes and the oxidation behaviour of phenothiazines to phenothiazine sulphones has been studied in detail.

     

Batch sizing under learning and forgetting: Steady state characteristics for the constant demand case

We analyze steady-state characteristics of batch production time for a constant-demand lot sizing problem with learning and forgetting in production time. We report a new type of convergence, the alternating convergence, in which the batch production time alternates between two different values.     

Bis(μ-iodo)bis((−)-sparteine)dicopper(I): versatile catalyst for direct N-arylation of diverse nitrogen heterocycles with haloarenes

The easy-to-prepare dimeric bis(μ-iodo)bis((−)-sparteine)dicopper(I) complex is shown to be a versatile catalyst for N-arylation of number of NH-heterocycles with structurally divergent aryl halides including activated aryl chloride substrates under mild conditions. The DFT studies not only provide structural insights into square-pyramidal Cu(III) intermediate complexes derived from (−)-sparteine, but also highlight the important role of sterically demanding (−)-sparteine ligand framework in promoting activation of aryl-chlorine bonds for N-arylation of imidazoles.