Kinetics and Mechanism of Oxidation of Ethylene Glycol Monoethylether by Diperiodatonickelate（IV） in Alkaline Medium

The kinetics of oxidation of ethylene glycol monoethylether (EGE) by diperiodatonickelate(IV) ion (DPN) was studied by spectrophotometry in alkaline medium. The reaction rate showed first order dependence on Ni(IV) and positive fractional order with respect to EGE. The pseudo-first order rate conslants, kobs increased with the increase of [OH^-] and decreased with the increase of [IO4^- ]. Added salts had little effect on the rate and no free radical was detected. Based on these,the mechanism including the equilibrium between DPN and EGE was proposed. Furthermore, the activation parameters of the reaction were calculated.     

Kinetics and Mechanism of Oxidation of Glycol by Dihydroxydiperiodatonickelate ( Ⅳ )Complex in Aqueous Alkaline Medium

The kinetics of oxidation of glycol by dihydroxydiperiodato nickelate ( Ⅳ) complex (DDN) was studied by spectrophotometry in aqueous alkaline medium in a temperature range of 25-40℃. The reaction was found to be first order with respect to Ni( Ⅳ ) and also to be first order with respect to glycol. The rate increases with the increase in [OH ] and decreases with the increase in [IO-4], showing that dihydroxymonoperiodatonickelate ( Ⅳ )(DMN) is the reactive species of oxidant. Salt effect indicated that the reaction is of ion-dipole type. No free radical was detected. A mechanism of an inner-sphere two-electron transfer reaction involving a preequilibrium between DDN and DMN is proposed, and the rate equation derived from the mechanism can explain all experimental observations. Activation parameters of the rate-determing step and the equilibrium constants were calculated.     

Kinetics and Mechanism of Oxidation of Lactic Acid by Dihydroxyditelluratoargentate（Ⅲ）in Alkaline Medium

The kinetics of the oxidation of lactic acid(Lac) by dihydroxyditelluratoargentate(Ⅲ）[abbreviated as DDA of Ag(Ⅲ）]anions was studied in an aqueous alkaline medium by conventional spectrophotometry in a temperature range of 25-40℃.The order of the redox reaction of lactic acid and DDA was found to be first-order.The rates increased with the increase in [OH^-]and decreased with the increase in [tellurate].No free radical was detected.In the view of this the dihydroxymonotelluratoargentate(Ⅲ）species(DMA) is assumed to be the active species.A plausible mechanism involving a two-electron transfer is proposed,and the rate equation derived from the mechanism can be used to explain all the experimenttal results.The activation parameters(25℃）and the rate constants of the rate-determining step along with the preequilibrium constants at different temperatures were evaluated.     

Theoretical Study on Reactivity of Electron Transfer in Model—System of Oxidation of α—Amino Carbon—centered Radical by O2

Electron transfer reaction between a simplified model model molecule of α－amino carbon-centered radical and O2 has studied with ab initio calculations at the MP2/6-31 G^**//UHF/6-31 G^** level,The reactant complex and the ion pair complex have been optimized and employed to perform calculation of the reaction heat and the reorganization energy,Solvent effects have been considered by applyning the conductor-like screening model,Theoretical results show that the highly endothermic charge separation process ,in which one electron transfers from the α－amino carbon-centered radical to O2,so as to form an ion pair complex,is difficult to occur in gas-phase,By apply-ing an external electronic field to prepare the charge-locallized molecular orbitals,the charge-separated state has been obtained using the initial-guess-induced self-consistent field technique,The theoretical investigations indicate that the solvent effect in the process of the oxidation of α-animo carbon-centered radical by O2 is remarkable.From the rate constant estima-tion ,it can be predicted that the oxidation of the model donor molecule by O2 can proceed,but not very fast.A peroxyl radi-cal compound has been found to be a competitive intermediate in the oxidation process.     

Exact quantum and TST-CEQ study of the collinear reaction O+HCl

Exact quantum calculations of reaction probabilities have been carried out using hyperspherical coordinates for the collinearr reaction O+HCl(v <1) -OH(v'<1)+Cl . A generalized LEPS potential energy surface with a barrier height of 8.12 kcal/mol has been used in the calculations. According to the calculated results we found that (1) the reaction probability oscillates with energy, (2) the reaction probability shows vibrational adiabaticity, although it is poorer than that for symmetric reaction Cl + HC1. The analysis of resonance has also been done. The reaction rate constants and average cross sections have been calculated by TST-CEQ method. The rate constants are in agreement with that by QCT and smaller than the experimental one. Finally, the threshold has been estimated and is in good agreement with that of the literature.     

Theoretical studies of the reactions of O(~3p) with halogenated methyl (Ⅰ)——Reaction mechanism of the O(~3p) CH_2Cl reaction

The reaction of O(~3P) with CH_2Cl radical has been studied using ab initio molecular orbital theory. G2 (MP2) method is used to calculate the geometrical parameters, vibrational frequencies and energies of various stationary points on the potential energy surface. The reaction mechanism is revealed. The addition of O(~3P) with CH_2Cl leads to the formation of an energy rich intermediate OCH_2Cl which can subsequently undergo decomposition or isomerization to the final products. The calculated heat of reaction for each channel is in agreement with the experimental value. The production of H CHClO and Cl CH_2O are predicted to be the major channels. The overall rate constants are calculated using transition state theory on the basis of ab initio data. The rate constant is pressure independent and exhibits negative temperature dependence at lower temperatures, in accordance with the experimental results.     

In-situ copolymerization of aniline with alkyl amine by APS： Kinetics and application

The kinetic study of in-situ eopolymerization of aniline with o- and p-methylaniline by ammonium persulfate （APS） has been carried out. UV-vis spectroscopic method was used to investigate the course of copolymerization. Structural characterization was studied by PT-IR spectral analysis. The electronic spectra of the copolymers poly（aniline-co-p-toluidine） and poly（aniline-co-o- toluidine） show blue shift. The shift has been observed in the bands corresponding to π→π^＊ transition as well as in the exciton transition. The increase in absorbance recorded during the reaction for different concentration of aniline, o- and p-toluidine at various intervals of time of polymerization reaction indicates a growth in the polymer formation. The resulting first-order rate constant was used to calculate the rate of copolymer formation using the rate equation -d[A]/dt = kc^n.     

A kinetic study of the electron-transfer in the reaction of tribenzylchlorotin with[CoW_(12)O_(40)]~(5-)

A kinetic study of the electron-transfer in the reaction of tribenzylchlorotin with potassium 12-tungsto cobalt(Ⅲ) ate ion, K_5[CoW_(12)O_(40)],abbreviated as Co(Ⅲ)W,has been performed in different solvents.The studies were carried out in methanol, ethanol,acetonitrile and acetic acid/water.The rate constants,reaction rates and activation parameters were calculated. Our findings show that the rate of disappearance of the Co(Ⅲ) is pseudo-first order.The kinetic data is strongly affected by used solvents.T...     

The effects of ultrasound frequency and power on the activation energy in Si-KOH reaction system

The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activation energy, and reducing activation energy is propitious to promoting a chemical reaction. In the present paper, the relationship between the activation energy in Si-KOH reaction system and the ultrasound frequency and power has been discussed for the first time. The range of ultrasound frequency and power is 40-100kHz （interval by 20kHz） and 10-50W （interval by 10W）, respectively. The experimental clata indicate that the activation energy decreases with the increasing ultrasound power. Comparing with the activation energy without ultrasound irradiation, the results in our paper indicate that ultrasound irradiation could reduce the activation energy in Si-KOH reaction system and increase the reaction rate.     

Kinetics and Mechanism of the Oxidation of Glycol by Dihydroxyditelluratoargentate(Ⅲ) with Spectrophotometry

The kinetics of the oxidation of glycol by dihydroxyditelluratoargentate (Ⅲ) complex(DDA) was studied in alkaline medium with spectrophotometry(in a temperature range of 16.6-40 ℃).The first-order rates with respect to glycol and Ag(Ⅲ) were all found.The rates increased with the increase in [OH-] and decreased with the increase in [TeO2-4].No effect was found with the addition of KNO3 and no free radical was detected.In view of this,the dihydroxymonotelluratoargentate(Ⅲ) species(DMA) is assumed to be the active species.A plausible mechanism involving a two-electron transfer is proposed,and the rate equation derived from the mechanism can explain all experimental observations.Activation parameters of the rate-determining step and constants are evaluated.     

Oxidation of n-Butanol and 2-Pentanol with Molecular Oxygen in Supercritical CO2

Oxidation of n-butanol and 2-pentanol using molecular oxygen in supercritical (SC) CO2 with and without co-solvent is investigated. The results showed that the reaction selectivity is high when the reaction is carried out in SC CO2. It has been observed that co-solvent affects conversion and selectivity of the reaction considerably.     

Kinetics and Mechanism of Iridium（Ⅲ）-Catalyzed Oxidation of Ethanol Amine by Cerium（ Ⅳ ） in Sulfuric Acid Media

In this study, the kinetics and mechanism of the iridium(Ⅲ)-catalyzed oxidation of ethanol amine(EAN) by cerium(Ⅳ) in a sulfuric acid medium was investigated using titrimetric technique of redox in a temperature range of 298—313 K. It was found that the reaction is of first order with respect to Ce(Ⅳ) and Ir(Ⅲ), and a positive fractional order with respect to EAN. It was also found that the pseudo-first-order([EAN][Ce(Ⅳ)]) rate constant kobs decreases with the increase of [H ] and [HSO-4]. Under the protection of nitrogen gas, the reaction system can initiate the polymerization of acrylonitrile, indicating the generation of free radicals. On the basis of the experimental results, a suitable mechanism was proposed. From the dependence of kobs on the concentration of hydrogen sulfate, Ce(SO4)2 was found to be the kinetically active species. The rate constants of the rate-determining step together with the activation parameters were evaluated.     

The synthesis and crystal structure of heteronuclear complex of lanthanide with sulfo-salicylic acid [Na3YLa2(C7H3SO6)4.26H2O]n

The titled complex has been synthesized by the reaction of sodium sulfo-salicylate with lanthanum and yttrium perchlorate. The crystal structure has been determined by single crystal X-ray diffractometry. The crystal is monoclinic with space group C2/c. The unit cell parameters are as follows: a=16.289(8), b=18.323(8), c=22.044(8) A, β=106.34(2)°, V=6314(6) A3, Z=4 and Dc=1.764 g/cm3. The structure was solved by direct method. The least-square refinement based on 3776 observed reflections [F > 6σ(F)] converged to a final R=8.6% and F(000) is 3548. Yttrium ion with eight-coordinate is located in central of the molecule, the two lanthanum ions with ten-coordinate are located at the two sides of yttrium ion. There are two positions for Na in the molecule, one is in the C2 axis with six coordinate, the other one is in a general position with five-coordinate.     

Kinetics and Mechanism of Iridium(Ⅲ)-Catalyzed Oxidation of Ethanol Amine by Cerium(Ⅳ) in Sulfuric Acid Media

In this study, the kinetics and mechanism of the iridium(Ⅲ)-catalyzed oxidation of ethanol amine(EAN) by cerium(Ⅳ) in a sulfuric acid medium was investigated using titrimetric technique of redox in a temperature range of 298-313 K. It was found that the reaction is of first order with respect to Ce(Ⅳ) and Ir(Ⅲ), and a positive fractional order with respect to EAN. It was also found that the pseudo-first-order([EAN](》)[Ce(Ⅳ)]) rate constant kobs decreases with the increase of [H ] and [HSO-4]. Under the protection of nitrogen gas, the reaction system can initiate the polymerization of acrylonitrile, indicating the generation of free radicals. On the basis of the experimental results, a suitable mechanism was proposed. From the dependence of kobs on the concentration of hydrogen sulfate, Ce(SO4)2 was found to be the kinetically active species. The rate constants of the rate-determining step together with the activation parameters were evaluated.     

Effect of Cationic Micelles on the Kinetics of Interaction of [Cr（Ⅲ）-Gly-Gly]^2＋ with Ninhydrin

The effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) on the interaction of chromium dipeptide complex ([Cr(Ⅲ)-Gly-Gly]2 ) with ninhydrin under varying conditions has been investigated. The rates of the reaction were determined in both water and surfactant micelles in the absence and presence of various organic and inorganic salts at 70 ℃ and pH 5.0. The reaction followed first- and fractional-order kinetics with respect to [Cr(Ⅲ)- Gly-Gly2 ] and [ninhydrin]. Increase in the total concentration of CTAB from 0 to 40×10-3 mol·dm-3 resulted in an increase in the pseudo-first-order rate constant (kψ) by a factor of ca 3. Quantitative kinetic analysis of kψ-[CTAB] data was performed on the basis of the pseudo-phase model of the micelles. As added salts induce structural changes in micellar systems that may modify the substrate-surfactant interactions, the effect of some inorganic (NaBr, NaCl, Na2SO4) and organic (NaBenz, NaSal, NaTos) salts on the rate was also explored. It was found that the tightly bound counterions (derived from organic salts) were the most effective.     

Catalytic Kinetics of the Schiff Base Metal Complexes Bearing Side Chain of Cyclic morpholine in Carboxylic Ester Hydrolysis

It has been reported that two Schiff base transition metal complexes bearing the side chain of the morpholine ring were synthesized and characterized, and two complexes with the same base agent but different metal ions were used as a simulant hydrolase in the catalytic hydrolysis of p-nitrophenyl picolinate in this paper. The mechanism of PNPP catalytic hydrolysis is proposed and supported by the results of the spectral analysis and the kinetic calculation. A kinetic mathematical model, applied to the calculation of the kinetic and thermodynamics parameters of PNPP catalytic hydrolysis, has been established on the foundation of the mechanism proposed. The result of the study shows that the two complexes have a good catalytic activity in PNPP catalytic hydrolysis, and the rate of the PNPP catalytic hydrolysis was increased with the increase of the pH values in the buffer solution and affected by the polarization effect of metal ion of the complexes.     

Liquid-Phase Selective Oxidation of Propane on Silica-Supported Nafion Catalysts

The liquid-phase partial oxidation of propane in the presence of the Fen+/H2O2 Fenton system at 70℃ and 1.4 atm on silica supported Nafion catalysts has been investigated. The reaction proceeds via a radical reaction path the efficiency of which is improved by silica-supported Nafion catalysts. Because of the direct relationship between reaction rate and concentration of sulphonic acid sites of Nafion catalysts, it is inferred that the active phase enahnces the kinetics of propane conversion by promoting the rate of active radicals generation.     

DFT Calculations for Electron Transfer Bond-breakingReaction of CH_3-X

Bond-breaking in electron tansfer (ET) reaction is a powerful synthetic tool to provide alkyl radicals. The reaction RX + e( ? R( + X( in gas-phase yields directly the alkyl radical and the halide ion. Although ab initio calculation has been performed to this kind of reaction for CH3-X1-3, density functional theory (DFT) has not been invoked so far. DFT is gaining popularity recently as a cost-effective procedure for studying physical properties of molecules. The activation energy ((G#) …     

阿莫西林与维多利亚蓝B的显色反应及应用

The color reaction of amoxicillin with victoria blue B was studied.A novel visible spectrophotometric method for the determination of amoxicillin has been established.Under pH 8.50～10.5 condition,victoria blue B reacteds with amoxicillin to form red ion association complex.The maximum absorption wavelength was at 630nm and the apparent molar absorptivity(ε) was 2.67×10~4 L·mol~(-1)·cm~(-1) and the linear ranges was 0～5.5 mg·L~(-1).Amoxicillin obey Beer's law in definite concentration range.The optimum reaction conditions and the methodological precision were studied simultaneity.The method was simple and rapid and sensitive for the determination of amoxicillin.This method has been applied to the determination of amoxicillin is in the city sell amoxicillin medicament is in point and average recovery at 98.2%～101.0%.     

CATALYTIC ACTIVITY OF Pd-Sn COMPLEX CARBONYLATION OF ACETYLENE

The influence of different concentration of HO, SnCl2, Cl- and n-BuOH on the carbonylation of acetylene has been studied. The results show that the yield of n- butyl propionate increases with the increase of HC1 concentration and the catalytic activity is depressed when Cl" concentration increases. However, the stability of catalytic complex is promoted by Cl-. The key to the carbonylation of acetylene lies in the addition of SnCl2, which promotes the formation of the complex of C2H2, CO with catalyst and plays an important role in the hydrogen removal from n-BuOH. The hydrogen removed from n BuOH is the hydrogen source of this reaction. Meanwhile, the principle of the effect of HCl, Cl- and SnCl2 on reaction has been discussed. The reaction model has also been proposed.