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101.
The kinetics of oxidation of substituted alcohols, RCH2CH2OH (R = H-, OEt-, OMe-, NH2-, Cl- and Br-) by sodium N-bromo-p-toluenesulfonamide or bromamine-T (BAT), catalyzed by ruthenium(III) chloride in the presence of HCl, has been studied at 303K. The reaction rate shows first order dependence each on [BAT], [alcohol] and [RuIII]. The reaction rate is inversely dependent on [H+]. Addition of halide ions and the reduction product, p-toluenesulfonamide has no significant effect on the rate. Composite activation parameters H, S and G were computed by studying the reaction at different temperatures (298–313K). The rate decreased in D2O medium and the solvent isotope effect k(H2O)|k(D2O) = 1.63 and 1.68 for EtOH and BrCH2CH2OH respectively. Proton inventory studies have been made in H2O–D2O mixtures for both alcohols. The conjugate acid, TsNHBr, is assumed to be the reactive species. The rates do not correlate satisfactorily with Taft substituent constants. The protonation constant (25.3) of monobromamine-T has been evaluated. From enthalpy-entropy relationships and Exner correlations, the isokinetic temperature () was found to be 368 K, which is much higher than the experimental temperature, indicating that enthalpy factors control the rate. The proposed reaction mechanisms and the derived rate laws are consistant with the observed kinetic data. The rate of oxidation of alcohols RCH2CH2OH follows the order: H > Br > OEt > OMe > Cl > NH2. 相似文献
102.
Manikyanahally N. Kumara Dase Gowda Channe Gowda Kanchugarakoppal S. Rangappa 《Reaction Kinetics and Catalysis Letters》2001,72(2):331-342
Synthesis and characterization of the dipeptides(DP) namely Glycyl-Proline (Gly-Pro), Alanyl-Proline (Ala-Pro) and Valyl-Proline (Val-Pro), were made. Kinetics of oxidation of these DP by Mn(III) have been studied in the presence of sulfate ions in acidic medium at 26C. The reaction was followed spectrophotometrically at max = 500 nm. A first order dependence of rate on both Mn(III) and DP was observed. The rate is independent of the concentration of reduction product, Mn(II) and hydrogen ions. Effects of varying dielectric constant of the medium and addition of anions such as sulfate, chloride and perchlorate were studied. Activation parameters have been evaluated using Arrhenius and Eyring plots. The oxidation products were isolated and characterized. A mechanism involving the reaction of DP with Mn(III) in the rate limiting step is suggested. 相似文献
103.
Atul N. Jadhav Chidananda Swamy Rumalla Bharathi Avula Ikhlas A. Khan 《Chromatographia》2007,66(9-10):797-800
Naturally occurring 20-hydroxyecdysone is an important anabolic ecdysteroid. A simple thin-layer chromatography method to quantitate 20-hydroxyecdysone in methanolic extract of the whole plant material of Sida rhombifolia L. was developed. This method was successfully applied for quantitative evaluation of dietary supplements. The separation was achieved on glass TLC plates coated with silica gel 60F254, using chloroform: methanol (8:2 v/v) as developing solvent. Densitometric evaluation of 20-hydroxyecdysone was performed at 250 nm in reflectance/absorbance mode. The calibration was in the range of 200–1,000 ng spot?1 and correlation coefficient for the calibration curve was >0.999. In addition, for six different Sida species unique fingerprints were obtained on the HPTLC plate. 相似文献
104.
Catalytic behavior of a magnesium-copper intermetallic alloy, Mg2Cu, in the hydrogenation of acetone has been studied in the temperature range of 393–423 K. A continuous flow type reaction was employed. Mg2Cu showed good catalytic activity with 2-propanol as the only product. A plausible mechanism for the mode of adsorption of acetone is proposed. 相似文献
105.
Y Anjaneyulu R Prabhakar Rao R Y Swamy A Eknath K Narasimha Rao 《Journal of Chemical Sciences》1982,91(2):157-163
A series of mixed ligand complexes of Hg(II) with the general formula Hg (OX) (SA) (where OX: 8-hydroxyquinoline, SA: salicylic,
5-chloro-, 3,5-dibromo, 3,5-diiodo, 3,5-dinitro, acetyl thiosalicylic acids) are isolated in pure state and characterised
by elemental analysis and infrared data. The low molar conductance of the complexes in dimethylformamide indicates non-electrolyte
nature. The antimicrobial activity of these complexes against various bacteria and fungi is studied which indicates that in
several cases, the mixed ligand complexes possess fairly highly antimicrobial activity than the binary mercury-oxinate. The
lipophilic tendency of these complexes and its influence on the antimicrobial activity is critically examined. A probable
mechanism for the toxic action of these complexes against various organisms is discussed. 相似文献
106.
An operationally simple, economical and straightforward synthesis of diverse oxazoles from oximes possessing a vicinal carbonyl group has been achieved by treatment of the latter with terminal diazo compounds like ethyl/benzyl diazoacetate and diazoacetophenone (which act as carbenoids) in one pot. At least two reducible functional groups (two ester groups or cyano?+?ester) are simultaneously introduced in one step. This reaction involves expulsion of a molecule each of N2 and water only as byproducts under copper catalysis. The structure of one of these oxazoles is confirmed by X-ray crystallography. Both the ester groups in the oxazole product could be reduced to alcohol moieties by using NaBH4/EtOH. 相似文献
107.
The linear stability of a viscoelastic liquid saturated horizontal anisotropic porous layer heated from below and cooled from
above is investigated by considering the Oldroyd type liquid. A generalized Darcy model, which takes into account the viscoelastic
properties, the mechanical and thermal anisotropy is employed as momentum equation. The critical Rayleigh number, wavenumber,
for stationary and oscillatory states and frequency of oscillation are determined analytically. It is shown that oscillatory
instabilities can set in before stationary modes are exhibited. The effect of the viscoelastic parameter, the mechanical and
thermal anisotropy parameters and specific heat ratio on the linear stability of the system is analyzed and presented graphically. 相似文献
108.
Arun Kumar Macharla Rohitha Chozhiyath Nappunni Mahender Reddy Marri Swamy Peraka Narender Nama 《Tetrahedron letters》2012,53(2):191-195
A highly efficient, environmentally safe and economic method for selective α-monobromination of aralkyl, cyclic, acyclic, 1,3-diketones and β-keto esters and α,α-dibromination of 1,3-diketones and β-keto esters without catalyst is reported using ammonium bromide as a bromine source and oxone® as an oxidant. The reaction proceeds at ambient temperature and yields range from moderate to excellent. Bromination of unsymmetrical ketones takes place at the less substituted α-position predominantly. Aromatisation of tetralones is also carried out with this reagent system. 相似文献
109.
110.
We present a formulation of deformed oscillator algebra which leads to intermediate statistics as a continuous interpolation between Bose-Einstein and Fermi-Dirac statistics. It is deduced that a generalized permutation or exchange symmetry leads to the introduction of the basic number and it is then established that this in turn leads to the deformed algebra of oscillators. We obtain the mean occupation number describing the particles obeying intermediate statistics which thus establishes the interpolating statistics and describe boson-like and fermion-like particles obeying intermediate statistics. We also obtain an expression for the mean occupation number in terms of an infinite continued fraction, thus clarifying successive approximations. 相似文献