Kinetic determination of silver ion by its perturbation on Belousov-Zhabotinskii oscillating chemical reaction using potentiometric method.

Silver ion can perturb the Belousov-Zhabotinskii (B-Z) oscillating chemical reaction. Therefore, the B-Z oscillating system was applied in the determination of silver ion by using a platinum wire as an indicator electrode in the potentiometric method. The amplitude of the potentiometric oscillation increased linearly in proportion to [Ag+] in the range of 9.42 x 10(-6) M to 2.54 x 10(-4) M, with a correlation coefficient of 0.999 under the optimum conditions. The obtained LOD (2sigma) was 8.85 x 10(-6) M and the relative standard deviation (RSD) for five measurements of 1 x 10(-4) M silver ion was 5%. The influence of some potentially interference was also investigated.     

Studies on activation of C-H bond and insertion reaction of CO,CO2 into M-C bond using (Ir(COD)(diphos))Cl complexes

Three new organoiridium complexes are prepared from (Ir(COD)(μ-Cl))₂ and diphosphine in 1:2 molar ratio, and characterized by means of IR, ¹H NMR electric conductivity and elemental analysis. Using acetonitrile as substrate. we investigated the abilities of these complexes to activate sp³ C-H bond and promote insertion reaction of CO, CO₂ into metal-carbon bond. The experimental results show that the activity of (Tr(COD)(diphos))Cl is correlated to the electronic property of diphosphine chelate ligand.     

Image processing using the Briggs-Raucher oscillating chemical reaction

Some images obtained by illuminating the Briggs-Raucher oscillating chemical reaction are illustrated. This reaction gives more distinct and contrasty images than the Belousov-Zhabotinskii reaction.

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间歇釜中BZ类均相无机振荡反应的研究

在间歇釜中, 以BrO3^--H2PO2^--Mn^2^+-Fe(phen)3^2^+-H2SO4为体系, 本文首次设计了一个纯无机均相BZ类化学振荡体系, 采用溴离子选择性电极和紫外可见分光光度计可分别观察到[Br^-],[Mn^3^+]和[Fe(phen)3^3^+]的振荡现象。对振荡反应产物及总反应计量关系进行了分析, 考察了反应物浓度和反应温度对体系振荡反应的影响, 并由此计算得到振荡反应的表观活化能, 研究了Cl^-,Br^-, Br2, 丙烯腈等因素对振荡反应的影响, 并由此对振荡反应的控制机理作了探索。对体系中两种金属离子的作用进行了分析。在此基础上提出了一种在间歇釜中设计均相BZ类振荡反应的新方法。利用这一方法, 不仅可以设计无机振荡反应, 而且还可以设计一系列由氨基酸、多肽、糖类等具有生物功能的物质参与的化学振荡, 有助于理解生物体内普遍存在的周期性现象。     

Determination of furfural in an oscillating chemical reaction using an analyte pulse perturbation technique

A rapid and convenient method for the determination of furfural is presented that is based upon sequential perturbation of the Mn(II)-catalyzed B-Z oscillating system with different amounts of furfural using a continuous-flow stirred tank reactor (CSTR). When the sample was injected, the change in the amplitude and/or period was linearly proportional to the logarithm of the concentration of furfural over the range 3×10⁻⁸∼1×10⁻⁵ mol L⁻¹. This method gave a detection limit of 3×10⁻⁹ mol L⁻¹ under optimum conditions. Finally, the possible mechanism of furfural perturbation in the oscillating reaction is discussed. When the furfural was injected into the Mn(II)-catalyzed B-Z oscillating system, the change in the amplitude and/or period was linearly proportional to the logarithm of the concentration of furfural over the range 3×10⁻⁸~1×10⁻⁵ mol L⁻¹, with a detection limit of 3×10⁻⁹ mol L⁻¹ under optimum conditions.      

[Ir(COD)(diphos)Cl配合物活化sp^3 C-H键及其促进CO、CO2插入Ir-C键反应性能的研究

本文利用[Ir(COD)(μ-Cl)]2与双膦螯合配位体之间的反应合成了三个新的配合物[Ir(COD)(diphos)]Cl(diphos=dmpe、depe、dppe),用IR、NMR、电导和元素分析测定了结构.以CH3CN为反应底物分别考察了它们活化sp^3C-H键的能力及其反应规律.在此基础上进一步研究了使CO、CO2插入生成的Ir-CH2CN键的可能性.结果表明:在温和条件下进行这一插入反应是可能的,并用光谱方法证实有相应的含羰基、羧基的金属配合物的生成.     

Bifurcation of irregular oscillatory regimes in the Belousov-Zhabotinskii reaction in a closed reactor

We describe the bifurcation diagram for irregular oscillatory regimes in the Belousov-Zhabotinskii reaction in a closed reactor upon variation of the initial concentrations of ferroin and potassium bromate. We formulate rules for transition from one regime to another.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol, 28, No. 5–6, pp. 474–478, September–December, 1993.     

Determination of sulfanilamide based on the Mn(II)-catalyzed oscillating chemical reaction

A convenient and sensitive method for determination of sulfanilamide (SNA) was described based on the Mn(II)-catalyzed oscillating chemical reaction. Under optimum conditions, a linear relationship existed between the changes of oscillating period or amplitude and the negative of logarithm of SNA concentration in the range of 4.27 × 10⁻⁸ mol ·L⁻¹ ∼ 7.41 × 10⁻⁶ mol ·L⁻¹ (RSD, 0.85%) and 9.33 × 10⁻⁸ mol ·L⁻¹ ∼ 3.02 × 10⁻⁶ mol ·L⁻1 (RSD, 1.08%), respectively. The lower limit of detection was found to be 2.69 × 10⁻⁸ mol ·L⁻¹ and 6.03 × 10⁻⁸ mol ·L⁻¹, respectively.      

Description of transient chaotic regimes in the Belousov-Zhabotinskii reaction by means of return maps

Transient chaotic regimes in the Belousov-Zhabotinskii reaction were described by means of return maps. A linear interrelationship was found between the largest Lyapunov exponents (LLE) of the return maps plotted and the LLE value characterizing the “scattering” of neighboring trajectories in the phase space of the system.     

Kinetics of the reaction Cl + NO2 + M

The termolecular rate constant for the reaction Cl + NO₂ + M has been measured over the temperature range 264 to 417 K and at pressure 1 to 7 torr in a discharge flow system using atomic chlorine resonance fluorescence at 140 nm to monitor the decay of Cl in an excess of NO₂. The results are\documentclass{article}\pagestyle{empty}\begin{document}$k_1^{{\rm He}} = 9.4{\rm } \times {\rm }10^{ - 31} \left({\frac{T}{{300}}} \right)^{ - 2.0 \pm 0.05} {\rm cm}^6 {\rm s}^{ - {\rm 1}}$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$k_1^{{\rm N}2} = (14.8{\rm } \pm {\rm }1.4){\rm } \times {\rm 10}^{ - 31} {\rm cm}^6 {\rm s}^{ - 1}$\end{document} at 296 K where error limits represent one standard deviation. The systematic error of k₁ measurements is estimated to be about 15%. Using a static photolysis system coupled with the FTIR spectrophotometer the branching ratio for the formation of the two possible isomers was found to be ClONO(?75%) and CINO₂(?25%) in good agreement with previous measurements.     

The reaction of dichlorotetracarbonyldirhodium,Rh2Cl2(CO)4, with t-buthyl Isocyanide

By studying the evolution of CO from Rh₂Cl₂(Co)₄ in various solvents with successive additions of t-BuNC and by measuring the conductances and infrared spectra of these solutions, the course of the reaction and the nature of the intermediates have been established. The intermediates RhCl(CO)₂(t-BuNC) and RhCl(CO)(t-BuNC)₂ in the formation of [Rh(t-BuNC)₄]Cl were isolated as blue-black solids from yellow solutions.     

A kinetics study of the reaction of Cl with NO2

The third order rate coefficients for the addition reaction of Cl with NO₂, Cl + NO₂ + M → ClNO₂ (ClONO) + M; k₁, were measured to be k₁(He) = (7.5 ± 1.1) × 10^?31 cm⁶ molecule^?2 s^?1 and k₁(N₂) = (16.6 ± 3.0) × 10^?31 cm⁶ molecule^?2 s^?1 at 298 K using the flash photolysis-resonance fluorescence method. The pressure range of the study was 15 to 500 torr He and 19 to 200 torr N₂. The temperature dependence of the third order rate coefficients were also measured between 240 and 350 K. The 298 K results are compared with those from previous low pressure studies.     

Competitive adsorption of NO, NO2, CO2, and H2O on BaO(100): a quantum chemical study

Density functional theory (DFT) quantum chemical calculations are used to determine adsorption energies and geometries of NO, NO(2), CO(2), and H(2)O on a barium oxide (100) surface. The study includes two adsorption geometries for NO(2). All species form thermodynamically stable adsorbates, and adsorption strength increases in the order NO(2) < H(2)O < NO 相似文献   

Improved sensitivity for some [corrected] metal ions by use of sulfide in the Belousov-Zhabotinskii oscillating reaction

A highly sensitive method for the determination of trace amounts of transition metal ions by use of sulfide in the Belousov-Zhabotinskii (B-Z) oscillating chemical reaction is proposed. The use of sulfide increased strongly the sensitivity of the B-Z reaction for transition metal ions, such as Ag⁺, Pb²⁺, Hg²⁺, Cd²⁺, Cu²⁺,and Bi³⁺. Results showed that the variational ratio of oscillating period (P_R) is linearly proportional to the negative logarithm of concentration of metal ions. The detection limit is down to 10⁻¹² mol L⁻¹. Various influencing factors on the determination were also examined.     

茚三酮对B-Z振荡反应的影响

研究了茚三酮对B Z振荡体系的影响,考察了振幅和周期的改变值与茚三酮浓度的关系。结果表明,在6.9×10-7～4.2×10-2mol/L范围内,第一振幅改变值与茚三酮浓度有良好的线性关系,相关系数为0.9977。依据FKN模型,对此反应机理进行了初步探讨。     

Kinetics and mechanism of the reaction of Cl atoms with CH2 CO (Ketene)

The kinetics and mechanism of the gas-phase reaction of Cl atoms with CH₂CO have been studied with a FTIR spectrometer/smog chamber apparatus. Using relative rate methods the rate of reaction of Cl atoms with ketene was found to be independent of total pressure over the range 1–700 torr of air diluent with a rate constant of (2.7 ± 0.5) × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ at 295 K. The reaction proceeds via an addition mechanism to give a chloroacetyl radical (CH₂ClCO) which has a high degree of internal excitation and undergoes rapid unimolecular decomposition to give a CH₂Cl radical and CO. Chloroacetyl radicals were also produced by the reaction of Cl atoms with CH₂ClCHO; no decomposition was observed in this case. The rates of addition reactions are usually pressure dependent with the rate increasing with pressure reflecting increased collisional stabilization of the adduct. The absence of such behavior in the reaction of Cl atoms with CH₂CO combined with the fact that the reaction rate is close to the gas kinetic limit is attributed to preferential decomposition of excited CH₂ClCO radicals to CH₂Cl radicals and CO as products as opposed to decomposition to reform the reactants. As part of this work ab initio quantum mechanical calculations (MP2/6-31G(d,p)) were used to derive Δ_fH₂₉₈(CH₂ClCO) = −(5.4 ± 4.0) kcal mol⁻¹. © 1996 John Wiley & Sons, Inc.     

The infrared chemiluminescent reaction of Cl atoms with H2CO

The reaction Cl + H₂CO → HCl + HCO has been studied at 295 K. Chlorine atoms were produced via the infrared laser induced dissociation of CCl₃F, using a pulsed CO₂ TEA laser. Using HCl infrared chemiluminescence as the diagnostic, we find the rate constant to be 7.4 ± 0.7 × 10^?11 cm³/molecule sec, in good agreement with several recent studies. An evaluation of TEA laser photolysis as a technique for the generation of chlorine atoms is made, and the relationship of this experiment to recent theories of infrared laser induced chemistry is discussed.     

Rate constant for the reaction Cl + HO2NO2 → products

The total rate constant for the reaction of Cl atoms with HO₂NO₂ was found to be less than 1.0 × 10^?13 cm³ s^?1 at 296 K by the discharge flow/resonance fluorescence technique. The reaction was also studied by the discharge flow/mass spectrometric technique. k_1a + k_1b was measured to be (3.4 ± 1.4) × 10^?14 cm³ s^?1 at 296 K. The reaction is too slow to be of any importance in stratospheric chemistry.     

Quantum chemical study of chlorine-dissociation of oxalyl chloride (ClCO)_2→2Cl+2CO

It is very difficult to study the phenomenon that molecules are decomposed into several pho-tofragments by UV light, as the energy of lamp-house is insufficient. But the bond energy in oxa-lyl chloride is relatively low, for example, D0(ClCOCO-Cl) = 313.92 kJ/mol[1], D0(ClCO-CO) = 35.53 kJ/mol, and D0(Cl-CO) = 27.17 kJ/mol[2], so, oxalyl chloride, as a typical system for the study of multi-channel dissociation, can be dissociated into the four fragments Cl+Cl+CO+CO by the proper UV …