催化动力学分析法测定超痕量钒的研究

在稀磷酸介质及活化剂抗坏血酸存在下,痕量钒(Ⅴ)强烈催化溴酸钾氧化碱性品红褪色,据此建立了一个新的测定超痕量钒的催化动力学光度法.方法测定钒(Ⅴ)的线性范围为:0.0～400.0 pg/mL,检出限为27 pg/mL.实验考察了影响催化反应速率的各种因素,确定了实验的最佳条件.测定了催化反应的动力学参数:表观活化能E0'=170.1 kJ/mol,表观速率常数k'=2.8×10-3s-1,建立了动力学速率方程:-dCMR/dt=K'.CMR.CKBrO3.CVc.CV(Ⅴ).试验了25种共存离子的影响,发现大多数常见离子不干扰,方法直接用于环境水体中超痕量钒的测定,相对标准偏差为1.65%～2.03%.     

偶氮胭脂红B-溴酸钾动力学光度法测定痕量钒

在有抗坏血酸作活化剂的条件下,微量钒(Ⅴ)能显著催化溴酸钾对偶氮胭脂红B(AZB)的氧化褪色反应。在研究了该催化反应的适宜条件和动力学参数的基础上,建立了测定痕量V(Ⅴ)的新催化光度法。该方法测定V(Ⅴ)的线性范围为1.0～3.2ng mL、检出限为1.1×10-2ng mL。对2ng mLV(Ⅴ)独立测定10次的相对标准偏差为0.20%。考察了40多种共存离子的影响,大多数共存离子不干扰测定。本法用于黄连、茶叶、大米和面粉中微量钒的测定,相对标准偏差为2.7%～3.9%,加标回收率为97.1%～105.4%。     

离子交换树脂分离富集催化动力学电位法测定痕量钒

研究了在稀硫酸介质中,以痕量钒(Ⅴ)催化溴酸钾氧化碘化钾的反应为指示反应,用碘离子选择电极跟踪Ⅰ-,建立了催化动力学电位法测定钒的方法.在一定的条件下,该指示反应为一级反应,反应速度可用电位的变化△E表示.当时间固定,△E与钒(Ⅴ)浓度在0.015～0.1 mg·L-1范围内呈线性关系.方法的检出限为3.2×10-7g·L-1.该法可用于钢铁样品中钒的测定,试样溶液中钒(VO3-4)预先从弱碱性溶液中(pH 7.0～8.2)用强碱性阴离子交换树脂分离.用1.0 mol·L-1硫酸从树脂上将钒(Ⅴ)洗脱后按所述方法测定.测定结果与标准值相符,相对标准偏差小于5%.     

钒-KBrO3-偶氮胭脂红B催化光度法测定痕量钒(Ⅴ)

在硫酸介质中,痕量钒能灵敏地催化溴酸钾氧化偶氮胭脂红B而褪色.研究了该催化褪色反应的最佳条件及动力学参数,建立了一种测定痕量钒(Ⅴ)的新方法.该法的线性范围为0～1.0 μg/10 mL,检出限为1.40×10-9 g/mL.用于水和小麦试样中钒(Ⅴ)的测定,结果满意.     

无机偶合反应化学发光分析 I.H_2O_2-Na_2S_2O_3-Luminol体系测定痕量钒

本文将钒(Ⅴ)催化过氧化氢氧化硫代硫酸钠的反应与Luminol-H_2O_2-K_3Fe(CN)_6体系的化学发光反应相偶合,用流动注射化学发光法测定痕量钒.化学发光强度与钒浓度在0.5—30ppb范围内呈线性关系,检测下限为4.3×10~(-10)g·mL~(-1),测定2ppb钒,相对标准偏差为3.2％.用离子交换法分离干扰离子,可用于天然水中钒的测定.     

催化分光光度法测定油品及催化剂中的痕量钒

1 引言 张改兰、张振辉利用钒(V)在乙酸介质中于100℃下能催化溴酸钾氧化铬蓝黑R褪色,而建立了测定钒的最灵敏的催化分光光度法,其Sandell灵敏度为7.27×10~(-8)μg/cm~2。我们发现ng数量级的钒能在室温下催化上述反应,且共存物质的干扰限大幅度升高,提高了方法的选择性,简化了操作,能满足石油加工工业对分析钒的要求。本文考察了室温下催化反应的条件及12种离子的干扰情况,成功地将该法应用于石油产品及催化剂中痕量钒的测定。测定范围为0.3～6ng/25ml,检测限为0.3ng/25ml。用0.1g样品能检测到3.0ppb钒。     

催化动力学光度法测定痕量钒(Ⅴ)的研究

在乙酸介质中,痕量钒(Ⅴ)对过硫酸钾氧化1 (2 吡啶偶氮)\|2 萘酚(PAN)褪色的指示反应有灵敏的催化作用。研究了该催化反应的最佳实验条件和动力学参数,建立了一种测定痕量钒(Ⅴ)的新方法,其线性范围为0.0～40.0μg/L钒(Ⅴ),方法检出限为2.62×10-9g/mL。     

催化动力学交流示波极谱法测定微量钒的研究

研究了在柠檬酸-柠檬酸钠缓冲溶液中,V(Ⅴ)催化过氧化氢氧化茜素红S的褪色反应A其动力学条件,建立了一种高灵敏度、高选择性测量微量V(Ⅴ)的新方法。测定V(Ⅴ)的线性范围为1．0～6．0μg·ml-1,检出限为0．50μg·ml-1,有色溶液及沉淀不干扰测定,优于催化光度法,使得用于常量分析的交流示波极谱法可以进行微量测定。方法用于合金钢中钒的测定,结果满意。     

催化光度法测定痕量钒(Ⅴ)

研究了稀盐酸介质中钒(V)催化溴酸钾氧化1-氨基-8-萘酚-3,6-二磺酸一钠盐形成红色产物的指示反应,建立了催化光度法测定痕量钒(V)的新方法。在55℃下恒温反应55min,加EDTA抑制反应,同时以流水冷却,于λ_(max)=436nm处测定催化反应和非催化反应的吸光度A和A_0,钒(V)含量在0～20ng/25mL与△A呈良好的线性关系,测定的检出限为3.6×10~(-2)ng/mL。对24种共存离子进行了干扰试验,结果表明,该实验的干扰离子主要为Cu~(2+)、Fe~(2+)离子,可借助于碱沉淀分离予以消除,也可以用磺基水杨酸掩蔽,或采用732阳离子交换树脂分离。该法用于松针、桂园等试样的分析,结果比较准确。     

钒(Ⅴ)催化溴酸钾氧化铍试剂Ⅲ的反应及其应用

基于在硫酸介质中钒(Ⅴ)催化溴酸钾氧化铍试剂Ⅲ的反应建立了测定痕量钒(Ⅴ)的新方法,研究了试剂浓度条件,讨论了反应机理,方法线性范围是0～0 50ng mL,检出限为7 0×10-12g mL,方法已用于矿泉水及蔬菜中钒的测定。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Summary of development of the theory of stability of colloids and thin films

In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Thermodynamics of the formation of oxosulfides of rare-earth elements

The enthalpies of solution of several oxosulfides of rare-earth elements and the high-temperature enthalpies of oxosulfides and oxosulfates of lanthanum and yttrium were measured using solution calorimetry and high-temperature microcalorimetry techniques. Standard enthalpies of formation and some thermodynamic properties of oxosulfides and oxosulfates were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2 pp. 294–297, February, 1997.     

探究“铁的锈蚀条件”实验创新设计

设计了铁的锈蚀实验,说明了铁钉的处理方法,增加了温度、酸、碱的影响条件,实现了铁跟蒸馏水及空气中氧气快速反应而生锈,使实验在5 min左右就能够得到准确的结果。