Co2+与BPPT络合反应动力学及动力学光谱法测定钴

Kinetics of complexation reaction of Co2+ with 2-benzoylpyridine-4-phenyl-3-thiosemicarbazone (BPPT)was spectrophotometrically examined at 421 nm. The ligand that is developed for a simple kinetic-spectrophotometric determination of Co2+ is based on 1:2 complex formation between Co2+ and BPPT. The complexation reaction was carried out in ethanol-water medium at 25 ℃. Kinetic and activation parameters of the complexation reaction were calculated, and the rate equation and the reaction mechanism were proposed. The calibration graph is linear in the concentration range of 0.10～2.91 mg·L-1 for the tangent method. The species that caused interference were investigated.     

催化动力学光度法测定微量钴的研究

在ｐＨ＝４．０的ＨＡｃ－ＮａＡｃ介质中，在避光条件下，钴对无色的Ｆｅ（Ⅲ）－联吡啶配合物还原成红色的Ｆｅ（Ⅱ）－联吡啶配合物有较强的催化作用。据此本文建立了微量钴的新催化动力学光度法，对钴的线性范围为０～１．０μｇ／ｍＬ Ｃｏ，检测限为０．０１８μｇ／ｍＬ。本法选择性较好，多数离子均允许大量存在。本法测定了维生素Ｂ１２及分子筛中的钴，获得满意的分析结果。并对钴的催化机理作了初步探讨。     

Co2（μ—C2ph2）（CO）6的取代反应动力学研究

有机膦的电子效应和空间效应有非常广泛的值域范围~[1],这两种效应对配合物的行为影响极大~[2,3],在反应动力学研究中,可直接影响甚至会决定化学反应的机理和速度~[4]。Poē等~[5]只研究了Co_2(μ-C_2ph_2)(CO)_6与几种锥角较小的膦配体进行取代反应的动力学,而对锥     

动力学光度法测定痕量钴的研究

催化动力学法测定微量Co~(2+)已有报道,方法灵敏度一般在10~(-6)～10~(-10g)数量级,多数用于测定水、血液和高纯物质中的Co~(2+),而测定中药內的痕量CO~(2+)还未见报道。本文研究了氨水介质中Co~(2+)催化二苯偶氮酰肼氧化褪色的新指示反应及动力学条     

偶氮KS催化动力学光度法测定痕量钴

研究了在乙酸盐（ｐＨ４．７）介质中，Ｃｏ（Ⅱ）催化过氧化氢氧化偶氮ＫＳ的褪色反应及其动力学条件，建立了一种超高灵敏，选择性好测量痕量Ｃｏ（Ⅱ）的新方法，可测定Ｃｏ（Ⅱ）０．００２５～０．１μｇ／２５ｍＬ，间接表观摩尔吸光系数为４．９×１０＾６，曾用于人发中痕量钴的测定，获得满意的结果。     

催化动力学荧光法测定茶叶中的痕量钴

在硫酸介质中,基于痕量Co2+对溴酸钾氧化罗丹明B的褪色反应有催化作用,建立了催化动力学荧光法测定Co2+的方法.在优化条件下,Co2+浓度在1.0×10-7～1.0×10-4 g/L范围内与荧光强度呈良好的线性关系,相关系数r=0.9986.方法的检出限为2.0×10-8g/L,对浓度为5.0×10-5g/L的C02...     

阻抑动力学光度法测定绞股蓝中痕量钴

基于钴(Ⅱ)在稀硫酸介质中对乙二胺四乙酸活化重铬酸钾氧化丁基罗丹明B的阻抑反应,建立了阻抑动力学光度法测定痕量钴(Ⅱ)的方法。检出限为2.65×10-6g.L-1,线性范围为0~0.60μg/25 mL,RSD<4%,平均回收率为98.5%,应用于实际样品中痕量钴的测定。     

Co/ZrO2/SiO2催化剂费-托合成反应动力学研究Ⅱ. 动力学模型的构建和回归

 在典型的Co系催化剂工业操作条件范围(T=473～503 K,p=1.5～4.0 MPa, H2/CO体积比=1.0～3.0)内,采用等温积分固定床反应器对Co/ZrO2/SiO2催化剂进行了F-T合成反应动力学研究. 依据详细可靠的基元反应机理,按照Langmuir-Hinshelwood-Hougen-Watson动力学推导方法,获得了Co系催化剂上基于详细反应机理的动力学模型. 通过动力学实验数据的回归分析,发现基于COs直接解离并以烷基为链增长中间体的表面碳物种机理的动力学模型可以较好地描述Co/ZrO2/SiO2催化剂上的F-T合成反应结果,该模型可自洽地描述F-T合成过程中的合成气消耗和烃产物分布状况,且获得的反应活化能等关键动力学参数与文献报道的理论结果基本一致.     

水杨醛缩氨基硫脲合钴(Ⅱ)的晶体结构及其荧光性质

在甲醇和DMF溶剂里,以Schiff碱水杨醛缩氨基硫脲(简写为HL)和六水二氯化钴合成了配合物[CoHL2].H2O.DMF.在配合物[CoHL2]中,钴(Ⅱ)原子具有扭曲的N2O2S2八面体配位构型,晶体通过分子间氢键作用形成二维的无限网状结构.红外光谱表明,配体在形成配合物后,νS=O,νC=O和νC=N红移.荧光光谱表明,配合物金属对配体n-π*激发引起的荧光发射峰有较大的影响.     

钴(II)酞菁与巯基乙醇轴向配位反应的动力学

用停流法研究了2,9,16,23-四羧基钴（Ⅱ）酞菁与2-巯基乙醇轴向配位的快速反应动力学,提出了较为合理的反应机理,用非线性及线性拟合的方法求得了各基元步骤的动力学参数,探讨了温度、pH等因素对反应的影响．     

Study of kinetics of complexation reaction of Co with 2-benzoylpyridine-4-phenyl-3-thiosemicarbazone and kinetic-spectrophotometric determination of cobalt

Kinetics of the complexation reaction of Co²⁺ with 2-benzoylpyridine-4-phenyl-3-thiosemicarbazone (BPPT) was spectrophotometrically examined at 421 nm. The ligand that was developed for a simple kinetic-spectrophotometric determination of Co²⁺ was based on 1:2 complex formation between Co²⁺ and BPPT. The complexation reaction was carried out in ethanol-water medium at 25 °C. Kinetic and activation parameters of the complexation reaction were calculated, and the rate equation and the reaction mechanism were proposed. The calibration graph is linear in the concentration range of 0.10−2.91 mg·L⁻¹ for the tangent method. The species that caused interference were investigated.     

2-benzoylpyridine-4-phenyl-3-thiosemicarbazone as an analytical reagent for spectrophotometric determination of iron

Summary The analytical possibilities of 2-benzoylpyridine-4-phenyl-3-thio- semicarbazone as reagent for the spectrophotometric determination of iron have been examined, and compared with other reagents with the same reactive grouping. Two procedures for the estimation of iron have been established.

---

Zusammenfassung Die Verwendbarkeit von 2-Benzoylpyridin-4-phenyl-3-thiosemicarbazon als Reagens für die spektrophotometrische Bestimmung von Eisen wurde untersucht und mit der Eignung anderer, die gleiche funktionelle Gruppe tragender Reagenzien verglichen. Zwei Verfahren für die Eisenbestimmung wurden ausgearbeitet.

     

钴系催化剂催化丁二烯—苯乙烯共聚动力学研究

合成高顺-1,4-丁苯胶的催化剂主要是镍、钴、钛系3类。钴系催化剂基本上是三元体系,也有加入添加剂(含N,O,S化合物)的多元体系。该体系的特点是,共聚物顺1,4含量高(～98％),分子量大。但苯乙烯的共聚活性低,有均聚苯乙烯和凝胶形成。本文以Co(nap)_2-Al_2Et_3Cl_3进行了丁苯共聚的动力学研究。     

Selective spectrophotometric kinetic determination of copper with 2-methyl-1, 3-cyclohexanedione bis(4-phenyl-3-thiosemicarbazone)

A non-catalytic kinetic method is described for the determination of copper(II), based on the slow rate of complexation between the metal ion and 2-methyl-1, 3-cyclohexanedione bis(4-phenyl-3-thiosemicarbazone), which is due to the slow syn/anti equilibration of the reagent. The reaction of pH <2 is followed by measuring the rate of change of the absorbance at 480 nm. The calibration graph is linear over the copper range 2–10 μg ml^?1, with relative standard deviations of 1.20% (tangent method), 1.85% (fixed-time method) and 1.75% (fixed-absorbance method). The only serious interferences are from Pd, Sb, Mo, Hg and periodate.     

钴(Ⅱ)催化过氧化氢氧化5-Br-TAMB的褪色反应动力学及其应用

研究了NaAc-HAc介质中钴(Ⅱ)催化H_2O_2氧化5-Br-TAMB的褪色的反应,测定了反应动力学参数,探讨了反应机理,并建立了测定痕量钴的新方法。本法检出限为1.8×10~(-10)g/mL,钴(Ⅱ)浓度在0～124.7 ng/12.5 mL范围内与1g(A_0/A)呈良好的线性关系。该体系已用于人发、茶叶中钴的测定,结果满意。     

钴配合物催化的乙烯与三烷基铝置换反应动力学研究

研究了用钴配合物催化的乙烯与三异丁基铝的置换反应动力学. 置换反应速率相对于烷基铝浓度、配合物浓度及乙烯压力呈一级关系. 置换反应速率的动力学方程为r=1.4 ×106[R3Al][Cat.][pC2H4]. 反应的活化能为71.9 kJ/mol.     

Thermodynamic and voltammetric studies of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone

Summary UV spectra, dc polarograms, cyclic voltammetry and coulometry measurements of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone (H₂ SPT) were recorded inBritton-Robinson buffer solutions ofpH 2–12. The dissociation constants of H₂ SPT evaluated spectrophotometrically and potentiometrically in a 5% (v/v)DMF-water mixture are concordant. The dc-polarograms in solutions ofpH<8.5 exhibit a single 4-electron diffusion-controlled polarographic wave, whereas in solutions ofpH>8.5 two waves are observed. The cyclic voltammograms give a single cathodic peak in acidic and neutral solutions, whereas two cathodic peaks can be identified in alkaline ones. An electrode mechanism is proposed and discussed. The effect of temperature on the dissociation constants and the polarographic data was also investigated; the corresponding thermodynamic parameters were derived and are discussed.

---

Thermodynamische und voltammetrische Untersuchungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon

Zusammenfassung UV-Spektroskopische, dc-polarographische, voltammetrische und coulometrische Messungen an Salicylaldehyd-4-(2-pyridyl)-3-thiosemicarbazon (H₂ SPT) inBritton-Robinson-Pufferlösungen (pH 2–12) wurden durchgeführt. Die spektrophotometrisch und potentiometrisch ermittelten Dissoziationskonstanten von H₂ SPT in 5% (v/v)DMF/Wasser stimmen überein. In Lösungen mit einempH-Wert unter 8.5 zeigen die dc-Polarogramme eine einzelne diffusionskontrollierte polarographische Welle (4e^–), während in Lösungen mit einempH-Wert von über 8.5 zwei Wellen zu beobachten sind. Die cyclischen Voltammogramme weisen in sauren und neutralen Lösungen einen, in basischen Lösungen hingegen zwei kathodische Peaks auf. Ein Elektrodenmechanismus wird vorgeschlagen und diskutiert. Der Effekt der Temperatur auf die Dissoziationskonstanten und die polarographischen Ergebnisse wurde ebenfalls untersucht. Die entsprechenden thermodynamischen Größen wurden bestimmt und werden diskutiert.

     

Kinetic and maximum-absorbance spectrophotometric methods for the determination of olanzapine

Two simple and sensitive spectrophotometric methods were developed for the determination of olanzapine (OLZ) based on its oxidation with potassium iodate in a sulfuric acid medium to produce an intense violet-colored species exhibiting a maximum absorbance at 537 nm. The initial rate of formation and the maximum absorbance of the violet-colored oxidized product were monitored, in the first and second methods. The various experimental parameters affecting the rate of development and stability of the oxidized product were carefully studied and optimized. Beer’s law was obeyed up to 4.0 and 7.0 μg cm⁻³ OLZ with correlation coefficients of 0.998 and 0.996 (n = 6) and detection limits of 0.1 and 0.15 μg cm⁻³, for the initial rate and maximum absorbance methods. The proposed methods were conveniently applied to the determination of OLZ in its dosage forms and in spiked serum samples. Correspondence: Ashraf A. Mohamed, Department of Chemistry, Faculty of Science, King Faisal University, P.O. Box 1759, Al-Hassa-31982, Saudi Arabia.