NO2-对乳酸-丙酮-BrO3--Mn2+-H2SO4化学振荡反应的影响

研究NO₂^-对乳酸-丙酮-BrO₃^--Mn²⁺-H₂SO₄化学振荡反应的影响时发现,NO₂^-对振荡反应的诱导期t_in、周期t_p有显著的影响。NO₂^-的浓度C_NO2^-与诱导期倒数的对数ln(1/t_in)、NO₂^-浓度的对数lnC_NO2^-与周期的对数lnt_p均有良好的线性关系,线性范围为7.46×10^-5～2.99×10^-3mol·L^-1。在此浓度范围内,NO₃^-无影响,是一重现性好,灵敏度高,操作简单的NO₂^-动力学分析测试体系。获得诱导期、周期的表观活化参数E_in、E_p分别为56.82kJ·mol^-1、64.51kJ·mol^-1。结合被动采样法,测得室外大气中NO₂日平均浓度值为1.59×10^-9mol·L^-1,最后对NO₂^-共存时的振荡反应诱导期机理进行了初步探讨。     

乙酰乙酸乙酯—BR化学振荡反应的研究

本文首次报道了乙酰乙酸乙酯－ＩＯ３＾－－Ｈ２Ｏ２－Ｍｎ＾２＋－Ｈ２ＳＯ４体系的化学振荡反应。研究了各种因素对振荡反应的影响，测定了最佳反应条件及振荡反应的浓度范围。研究了温度变化对振荡反应的影响，并计算了振荡反应的表观活化能，对振荡反应产物进行了分析，并测定了体系主要反应的计量关系，采用ＵＶ法对金属离子的作用和催化机理作了研究，探讨了ＢＲ反应中Ｉ２的产生机理及消耗机理，对体系中有关反应物的作用作了     

GA-BrO3——H2SO4-Mn2+体系的复杂振荡反应的研究

本文报道GA-BrO_3~--H_2SO-(4~-)Mn~(2 )体系的复杂振荡反应,这种在一个均相封闭体系中同时出现三种不同类型的连续振荡反应及混乱振荡反应至今尚未见报道。实验部分1.试剂:实验中所采用的各种试剂均为分析纯,溶液都用去离子水配制。2.实验仪器及方法:实验在恒温30±0.15℃下进行,以溴离子选择电极和PXS-215型离子活度计测量电位的变化来反映[Br~-]的变化,以Hg|Hg_2SO_4|K_2SO_4为参比电极,实验结果用XWT-台式自动平衡记录仪记录。     

KBrO3-Na2SO3-K4Fe(CN)6体系pH振荡可控调节模拟研究

作为非线性化学的重要分支,pH振荡在生物学、物理学、医药学等众多领域中都发挥着重要的作用,需重点关注pH振荡反应机理及其数学模型的研究。本文通过实验验证化学计量网络分析(SNA)模型的准确性,并研究了KBrO₃-Na₂SO₃-K₄Fe(CN)₆反应体系(BSF反应)的动力学机理,结果表明流速越大,振荡反应振幅越小,周期越大。将遗传算法与传统的SNA模型进行结合,建立了pH振荡可控调节的方法,实现了BSF反应的周期与微幅值控制,指导应用中对振荡反应的可控调节。     

甲醛-乳酸-丙酮-Mn2+-BrO-3-H2SO4振荡反应动力学分析研究

甲醛对乳酸 丙酮 Mn2+ BrO-3 H2SO4化学振荡反应的诱导期tin有显著的影响,甲醛浓度的对数ln[HCHO]与诱导期倒数的对数ln(1/tin)有良好的线性关系,线性范围为5.0×10-8～1.0×10-3mol·L-1。在此浓度范围内,该体系是一重现性好,灵敏度高,操作简单的甲醛动力学分析测试体系。获得的诱导期、周期的表观活化参数Ein、Ep分别为64.7kJ·mol-1、65.0kJ·mol-1。     

GA-KBrO3-H2SO4体系化学振荡的研究

研究了GA(没食子酸)-KBrO_3-H_2SO_4体系的诱导期τ、振荡周期T_2与反应物起始浓度的依赖关系, 302 K时的经验式为τ=22.8 c~(-2.23)_(H_2SO_4) c~(-2.17)_(KBrO_3) c~(0.795)_(GA) (mol.dm~(-3))~(4.25)·sT_2=0.84 c~(-2.28)_(H_2SO-4)c~(-1.97)_(KBrO_3) exp{(0.000147(mol.dm~(-3))~2/c~2_(GA)}(mol.dm~(-3))~(4.25)·sτ及T_2都随~CGA的增加而增长, 这与B-Z反应中关于有机物的结论不同。用循环伏安法研究该体系的结果表明, GA在诱导期结束时就基本上都被氧化为中间物, GA并不象前人所认为的是维持振荡的物种, 实际参与振荡的是由GA生成的物质。本文还研究了Fe(Phen)_3~(2+)对GA-KBrO_3-H_2SO_4体系振荡的影响, 发现Br~-振荡行为随Fe(Phen)_3~(2+)的浓度而变。低~CFe(phen)_3~(2+)时,Br~-的振荡行为与GA-KBrO_3-H_2SO_4体系的基本相似, 其特征是每个振荡周期内, Br~-振荡脉冲发生前是逐渐积累的。随着~CFe(phen)_3~(2+)的增大, Br~-出现另一特征的振荡行为, 在每个振荡周期内, Br~-振荡脉冲发生前是逐渐减小。我们认为, GA-KBrO_3-H_2SO_4-Fe(Phen)_3~(2+)体系的振荡不能单一地用OKN机理加以解释, 它可能是两套振荡机理耦合的振荡。     

以衣康酸-BrO-3-Mn2+为体系的化学振荡研究

本文研究了BrO_3~--Br~--H~+-Mn~(2+)-衣康酸体系的振荡行为, 利用电位法及分光光度计对体系做了一系列测定, 根据FKN机理, 提出了本体系可能的反应进程, 同时测定了各种反应条件对振荡的诱导期及周期影响, 并根据机理分析把诱导期分成两个部分, 得到1/τ_(i1), 1/τ_(i2), 1/τ_p对各种反应物起始浓度的关系式。还发观葡萄糖能促进振荡进行。     

丝氨酸-BrO^-~3-Mn^2^+-H2SO4体系振荡反应的研究

首次报道了间歇釜中以丝氨酸(Ser)-BrO^-~3-Mn^2^+-H2SO4为体系(简称Ser-BZ体系)的新型BZ类振荡反应,其特征如下：(1)虽然Ser不能发生溴代反应,但即使在无丙酮或惰性气体流时也能在间歇釜中观察到持续振荡;(2)振荡诱导期极短(～0),振荡次数较少(<11次);(3)振荡反应受到Cl^-,Br^-,丙烯腈等的抑制;但当加入足够量Ag^+使[Br^-]的振荡抑制后,仍可在Pt电极上观察到振荡现象。根据上述特征和反应产物分析,推测Ser-BZ振荡反应可能是自由基-控制模型,而非Br^--控制模型。加入适量丙酮可诱导连续振荡反应,归因于两种控制模型的共存。通过对Mn^3^+-Ser和BrO^-~3-Mn^2^+反应的动力学研究,并结合FKN机理,对Ser-BZ振荡反应机理进行了初步讨论。     

葡萄糖-BrO-3-Mn2+-H2SO4-丙酮体系的振荡反应

本文首次报道葡萄糖(以Glu表示)-丙酮(Act)-Mn~(2+)-BrO_3~--H_2SO_4体系的化学振荡反应,这种由糖类及丙酮作混和底物的均相B-Z振荡反应至今尚未见报道。实验部分1.试剂及药品:实验中各物质均采用分析纯,溶液在去离子水中配制。2.实验仪器及方法:实验在恒温30°±0.2℃下进行,以溴离子选择性电极和PXS-215型离子活度计测量电势(E)随时间(t)的变化来反映log[Br~-]的变化,以Hg|Hg_2SO_4|K_2SO_4为参比电极,振荡现象可通过XWT-台式自动平衡电位记录仪记录的E～t曲线观察,同时也可采用HP-8451A型紫外可见分光光度计,测定特定波长下吸光率的变化反映读物质浓度的变化,实验时溶液均匀搅拌。     

邻菲罗啉对KBrO_3-Na_2SO_3-K_4[Fe(CN)_6]-H_2SO_4 pH振荡体系的扰动

本文研究了邻菲罗啉对KBrO3-Na2SO3-K4[Fe(CN)6]-H2SO4振荡体系的扰动。结果表明,当加入邻菲罗啉的浓度在0.0005~0.0035mol·L-1范围内时,导致KBrO3-Na2SO3-K4[Fe(CN)6]-H2SO4pH振荡体系的Pt电极电位、溴离子选择电极电位和pH振荡的周期和振幅均明显放大,而加入邻菲罗啉的浓度在0.004~0.013mol·L-1范围内时,该体系的振幅缩小。另外,本文就邻菲罗啉对KBrO3-Na2SO3-K4[Fe(CN)6]-H2SO4pH振荡体系的影响机理进行了讨论。     

氨基酸-BrO-3-Mn2+-H2SO4-丙酮体系的振荡反应

This paper, Using potentiometric method, first reports the oscillating behavior of five amino acids (L-methionine, L-cystine, L-tryptophan, L-serine, L-tyrosine) in a new oscillating system of amino acid-BrO_3~--Mn~(2+)-H_2SO_4-acetone. The effect of many factors on oscillation have been investigated. According to Arrhenius equation, the apparent activation energy of the oscillatary induction period and oscillation period of five oscillating systems are obtained within temperature range of 20～37 ℃.     

Metastable Equilibrium in Quaternary System Li2SO4 ＋ K2SO4＋Li2CO3 ＋ K2CO3 ＋ H2O at 288 K

IntroductionThe Zhabuye salt lake, Tibet in China, is famousfor the high concentrations of lithium, boron, andpotassium in the world. The main components areLi , K , Na , B4O72 -, CO32 -, Cl-, SO42 -, andH2O, including rare elements such as Rb and Cs .The…     

Kinetics of Mn2O3 digestion in H2SO4 solutions

The kinetics of Mn₂O₃ digestion in various H₂SO₄ solutions (0.5-2.0 M) and at various temperatures (ambient to 80 °C) to form solid γ-MnO₂ and soluble Mn(II) have been examined using X-ray diffraction. Using a modified first-order Avrami expression to describe digestion kinetics, rate constants in the range 0.02-0.98 h⁻¹ were found for Mn₂O₃ disappearance, and 0.03-0.42 h⁻¹ for γ-MnO₂ formation, with higher H₂SO₄ concentrations and temperatures leading to faster conversion rates. Also, for a particular set of experimental conditions, the rate of γ-MnO₂ formation was always slower than Mn₂O₃ disappearance. This was interpreted in terms of the solubility and stability of the soluble Mn(III) intermediated formed during the digestion. Activation energies for Mn₂O₃ dissolution and γ-MnO₂ formation were also determined.     

Investigation of phase equilibria in the systems K2SO4Sc2(SO4)3, Rb2SO4Sc2(SO4)3 and Cs2SO4Sc2(SO4)3

Phase diagrams of the systems K₂SO₄Sc₂(SO₄)₃, Rb₂SO ₄Sc₂(SO₄)₃ and Cs₂SO₄ Sc₂(SO₄)₃ have been investigated by X-ray diffraction phase analysis and differential thermal analysis techniques. A salient feature of all the systems is the formation of M₃Sc(SO₄)₃, which melt incongruently, and MSc(SO₄)₂, which on heating decompose in the solid state.     

丙炴醇聚合膜对铁在酸性溶液中的缓蚀作用

The formation of polymer film of propargyl alcohol(PA) and its protective ability against corrosion in Fe/H_2SO_4 and Fe/H_2SO_4+H_2S systems have been investigated using impedance measurement. The composition and morphology of the corrosion surface of iron, on which PA polymerized at different bines, were obtained with the aid of SEM and AFM as well as EDX. The results showed that PA polymerized into compact polymer film in Fe/H_2SO_4 and Fe/ H_2SO_4 + H_2S systems, which made iron surface smooth and have a morphologies of regular square structure in microscopic level. In Fe/H_2SO_4 system, macroscopic continuous polymer film of PA was not formed leading to local corrosion on electrode surface. In Fe/H_2SO_4 +H_2S system, the adsorption of H_2S and HS - on electrode surface slowed down the formation of polymer film of PA. However, the iron sulfide, produced after a longer time, increased the continuity of the polymer film of PA and therefore, the polymer film could perform its long-te...更多rm inhibition action.     

光引发BrC2F4Br+C2F4调聚反应的光强影响

实验发现，在光引发BrC2F4Br＋C2F4调聚反应中，光强（或光功率密度）能影响产品分布。提出了反应机理：此反应由加成反应与复合反应组成，而链转移反应可忽略．由此进行了动力学计算，为与实验结果吻合，拟合得的加成反应BrC2F4＋C2F4的速率常数为（2±1）×107cm3•mol-1•s-1，Br（C2F4）n≧2＋C2F4的速率常数为（1．2±0．4）×107Cm3•mol-1•s-1     

DSC investigation of the thermal behaviour of (NH4)2SO4, NH4HSO4 and NH4NH2SO3

Gaseous products evolved from (NH₄)₂SO₄, NH₄HSO₄ and NH₄NH₂SO₃ during successive heating and cooling cycles were flushed with inert gas into analyzer Dräger tubes hooked tightly to the terminal port of the DSC cell base. This simple procedure allowed the starting temperature of the decomposition to be determined and the amount of the individual gases in the mixture to be identified and even estimated. NH₄NH₂SO₃ at 523 K in humid air produced HNH₂SO₃ initially and, on further cycling, (NH₄)₂SO₄ and NH₄HSO₄ also appeared. The ΔH_f values for NH₄HSO₄ were (kJ mole^?1): in an airtight sample holder 12.67, in a dry argon atmosphere 11.93, and in a static air atmosphere 10.92. Endothermic peaks for (NH₄)₂SO₄ and 498 and 411 K represented the incongruent melting point and the polymorphic transition of (NH₄)₂SO₄·NH₄HSO₄. After the first heating in air to 530 K, (NH₄)₂SO₄ and NH₄HSO₄ exhibited closely similar cyclic DSC curves. The endothermic peaks at about 393–420 K may be assigned to different combinations of (NH₄)₂SO₄ and NH₄HSO₄.     

全氟烷基磺酸酯C—O键断裂的同面SN2反应

用密度泛函理论研究了CF₃SO₃CF₂CF₃＋F^－的碳氧键断裂反应的机理. 首先, 用DFT方法优化了反应物、中间体、过渡态、产物的平衡构型, 分析了碳氧键断裂反应的势能面变化. 发现在S_N2反应机理中, 除了S—O断裂S_N2反应外, 引起C—O键断裂的同面进攻也是一个可能的反应途径. 理论计算表明, 最终反应的产物是受热力学控制的, S—O键的断裂绝对地优于C—O的断裂. 因此, C—O断裂的同面机理虽然是可能的, 但却难以被实验观察到. 本文还讨论了端基 —F₃在同面S_N2反应中的邻位效应, 以及基组对这个效应的影响.