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431.
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. 相似文献
432.
Ram Chand Paul Surinder Kumar Gupta Veena Goyal Sham Kumar Vasisht 《Monatshefte für Chemie / Chemical Monthly》1977,108(5):1019-1025
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. 相似文献
433.
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. 相似文献
434.
Ranjeet Kumar J. R. Yadav D. D. Rao Lal Chand 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(3):787-790
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. 相似文献
435.
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.
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.相似文献
436.
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. 相似文献
437.
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. 相似文献
438.
The stability of an affine coalescence hidden variable fractal interpolation function is proved in a general set up in the present work, by establishing that any small perturbation in the generalized interpolation data leads to a small perturbation in the corresponding affine coalescence hidden variable fractal interpolation function. 相似文献
439.
Comparative charge transfer studies in nonmetallated and metallated porphyrin fullerene dyads 下载免费PDF全文
Neha Gupta Samya Naqvi Mukesh Jewariya Suresh Chand Rachana Kumar 《Journal of Physical Organic Chemistry》2017,30(11)
Single material organic solar cells become an interesting area of research to overcome the challenges with efficient charge separation efficiencies in conventional organic solar cells. In this article, we have synthesized nonmetallated and metallated porphyrin‐fullerene dyad materials (H2P‐C60 and ZnP‐C60, respectively) with simple structure, comprehensively studied their charge transfer mechanism, and established a proof of concept that nonmetallated porphyrin‐fullerene dyads are better candidates to be used in organic solar cells compared with metallated dyads. Absorption and electrochemical analysis revealed the ground state electronic interactions between donor‐acceptor moieties in both types of dyads. Driving force (?ΔGoET) for intramolecular electron transfer process was calculated by first oxidation and reduction potentials of dyads. The excited state electronic interactions were characterized by time‐resolved fluorescence and pump‐probe transient absorption experiments. Strong fluorescence quenching of porphyrin along with reduced lifetimes in dyads due to deactivation of singlet excited states by photoinduced charge transfer process between porphyrin/Zn‐porphyrin core and fullerene in different polarity solvents was observed. Transient absorption spectroscopy was also applied to identify the transient spectral features, ie, cationic (H2P+/ZnP+) and anionic (C60?) radicals formed because of the charge separation in both types of dyads. Finally, organic solar cell device was also fabricated using the dyads. We obtained higher Voc, Jsc, and fill factor in single material organic solar cell using H2P‐C60 compared to previous reports. 相似文献
440.
Modal analysis of non-uniform bolted structures are of significance in modeling many complex mechanical structures. There are vast literatures available related with the analytical as well as numerical modeling of bolted joint. However, most of the analytical model discuss about the modeling of first mode of uniform structures with single bolted joint. In this paper, we present the modeling of single as well as bolted non-uniform beams using approximate mode shapes. To develop the model, we first carry out experiments to measures the modal frequencies and shapes of the test structures. Subsequently, we also do numerical modeling of non-uniform beams in ANSYS to verify the validity of the Euler-Bernoulli beam theory in developing the analytical models. Finally, using the Euler-Bernoulli beam theory, we obtain the analytical values of frequencies using the approximate the mode shapes. The analytical results are found to be closer to the experimental results with a maximum percentage error of about 15 %. The model presented in the paper can be extended to the mechanical structures with many non-uniform sections with or without bolted joints. 相似文献