铌-(5-Br-PADAP)-羟基酸体系混合型络合物的研究

在酒石酸、柠檬酸、草酸和其它羟基酸存在时,研究了铌和2-[(5-溴-2-吡啶)偶氮]-5-(二乙氨基)苯酚(简称5-Br-PADAP)的反应。发现在酒石酸(Tar)存在时,使用5-Br-PADAP测定铌得到最好的结果。本文用吸光光度法研究蓝色的铌-(5-Br-PADAP)-Tar的混合型络合物。在PH为1.0-4.0范围600毫微米处,此蓝色络合物有最大的吸收。摩尔吸光系数是5.7×10⁴。用两种不同的方法研究混合型络合物的组成,Nb:5-Br-PADAP:Tar=1:1:1。在pH为1.0时,Nb的浓度1-32微克/25毫升范围内遵从比尔定律。本文提出高灵敏度和高选择性的吸光光度法测定合金钢中的微量铌。     

Extraction-spectrophotometric determination of iron(II) by ternary complex formation with pyrocatechol violet and cetyltrimethylammonium bromide

A method for iron(II) determination based on reaction with Pyrocatechol Violet to form a 1:2 binary complex at pH 5-7 is described and has been extended to an extraction-spectrophotometric procedure for the determination of iron(II) by formation of the 1:2:2 iron(II)-Pyrocatechol Violet-cetyltrimethylammonium bromide ternary complex. The molar absorptivities of the binary and ternary complexes at 595 and 605 nm are 6.55 x 10(4) and 1.35 x 10(5)1.mole(-1).cm(-1), respectively. The method has been successfully applied to the determination of iron in felspar, Portland cement and sodium hydroxide.     

CO2化学利用的一条新途径

C02开发利用一直是世界各国大型化工企业异常关注的研究课题，但是，由于C02结构稳定，化学活性差，因而决定了该领域的研究课题难度较大，进展比较缓慢．本文报道了一种利用天然气还原C02制备会成气的最新研究结果，该过程不仅可以为破一化学工业提供廉价原料，从而开辟一条极重要的非石油原料的化学工业路线，而且对减缓全球性温室效应也具有一定的社会意义．1实验日分1·1催化剂制备按表1所列组成，以7－AI。0。、硝酸镍、硝酸镁和稀土硝酸盐为原料，采用常规浸渍法参照文献［‘］制备催化剂．1·Zfffe反应评价催化反应评价采用双套管…     

Determination of herbicides and their metabolites in natural waters by capillary zone electrophoresis combined with dispersive liquid-liquid microextraction and on-line preconcentration

A method has been proposed for the determination of 17 herbicides and their metabolites in natural waters by capillary zone electrophoresis with UV detection at 190 nm. Dispersive liquid-liquid microextraction with trichloromethane has been used for pesticide recovery from water. The high sensitivity of determination has been provided by additional intracappilary preconcentration: the limits of pesticide detection in water involving off- and on-line preconcentration are 0.5–3.0 μg/L. The analysis takes 1–1.5 h; the relative standard deviation of the analysis results does not exceed 5%.     

生物样品的微波-酸消解电感耦合等离子体原子发射光谱多元素同时分析

对不同类型的生物样品的微波酸消解法与常规酸消解法作了比较研究,方法用于茶叶和贻贝标准参考物质的定值分析,取得满意结果.     

Subsolidus phase diagrams of the systems Cs2MoO4-R2(MoO4)3-Zr(MoO4)2, where R = Al, Sc, or In

The systems Cs₂MoO₄?R₂(MoO₄)₃?Zr(MoO₄)₂, where R = Al, Sc, or In, have been investigated in the subsolidus region by X-ray powder diffraction. Quasi-binary joins have been revealed, and triangulation has been carried out. Six new triple molybdates have been prepared with the component ratio equal to 1 : 1 : 1 (mol/mol) (S ₁) and 5 : 1 : 2 (S ₂). The crystal parameters for the 5 : 1 : 2 compounds have been determined, and the electrical properties of the 1 : 1 : 1 compounds have been investigated.     

Investigations in the 1,2,4-triazole series

To select a method for the synthesis of the previously difficulty accessible 5-bromo-1-phenyl-1,2,4-triazole (I) and 1-phenyl-1,2,4-triazoline-5-thione (II), a MO LCAO calculation has been carried out in Huckel's approximation of the energies of the radical, electrophilic, and nucleophilic localization on the various carbon atoms of 1-phenyl-1,2,4-triazole (III). In accordance with this calculation, the required compounds have been obtained in good yields by reactions taking place by a radical mechanism: I by bromination with bromosuccinimide and II by the direct thionation of III. The high reactivity of the bromine atom in position 5 has been noted.For part VIII, see [1].     

Poly(m-phenylene disulfide): Antimony pentafluoride doping and infrared spectroscopy

Poly(m-phenylene disulfide) treated with SbF₅ gives an unstable blue-black material. Heating of doped samples at 155°C leads to some stabilization to ambient conditions; doped and heated pellets exhibit a conductivity of 10^?9 and 10^?5 S/cm for vapor and liquid doping, respectively. To investigate backbone modifications, polymer powders have been treated with large amounts of liquid SbF₅ and an analysis of the IR spectra of the extracted samples has been tried in comparison with that of pristine polymer. Evidence for SbF ion has been found in the IR spectra of the complexes.     

Polargraphic adsorptive waves of alkaline-earth metal complexes with thymolphthalexone

Sensitive derivative polarographic adsorption waves have been observed for alkaline-earth metal-TP complexes in 0.15M potassium hydroxide containing 3 x 10(-5)M thymolphthalexone (TP). The limit of detection for calcium, strontium and barium was 7.5 x 10(-7)M and for magnesium 4.0 x 10(-6)M. The proposed method has been used successfully for determining trace amounts of calcium in natural waters and hair samples. The composition of the complex has been shown to be 1:1 alkaline-earth metal:TP and various experiments have confirmed that the wave is an adsorption wave. The reaction mechanism has been studied by a number of methods.     

On the synthesis and reactivity of the Z-2,4-dinitrophenylhydrazone of 5-amino-3-benzoyl-1,2,4-oxadiazole

The synthesis of the title compound (4b) has been completed: its rearrangement (in dioxane/water; 1:1, v/v) into N-(2,4-dinitrophenyl)-5-phenyl-2H-1,2,3-triazol-4-ylurea (7) has been quantitatively studied in a wide reactivity (at 293 K, k(A) 10(-8) -4 s(-1)) and pS+ (4.5-14.1) range and compared with that of the Z-2,4-dinitrophenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (10), of the 3-(p-nitro)phenylureine of 5-phenyl-1,2,4-oxadiazole (13), and of N-(5-phenyl-1,2,4-oxadiazol-3-yl)-N'-p-nitrophenylformamidine (14). The results (reactivity, occurrence of specific or general base-catalysis, evidence for or absence of rate-limiting constants) have been well interpreted considering the structure of the side-chains involved and the stability of the final rings obtained in the rearrangements.     

1,5-二(2-羟基-5-氯苯基)-3-氰基甲 催化动力学光度法测定痕量锰(II)

The aerial oxidation of 1, 5-bis (2-hydroxy-5-chlorophenyl)- 3-cyanoformazan (HCPCF) in ammoniacal medium catalyzed by Mn(II) has been investigated and used for spectrophotometric determination of trace Mn(II) in water. The effect of various experimental factors was studied and the optimal conditions for Mn(II) determination were found. It has been shown that the reaction follows the rate expression:     

Colour reaction of platinum(II) with 5-(4-nitrophenylazo)-8-(p-toluenesulphonamido)-quinoline and its analytical applications

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of platinum. 5-(4-Nitrophenylazo)-8-(p-toluenesulphonamido)quinoline (NPTSQ) reacts with platinum(II) almost instantaneously in alkaline solution to form a violet-red 1:2 complex with an absorption maximum at 640 nm. Beer's law is obeyed over the concentration range 0-1 mug/ml platinum. The molar absorptivity is 1.37 x 10(5) 1.mole(-1).cm(-1). The method has been used for the determination of microamounts of platinum in catalysts and anode slime.     

Tuning of the structures of chiral phosphane-phosphites: application to the highly enantioselective synthesis of alpha-acyloxy phosphonates by catalytic hydrogenation

A family of new chiral phosphane-phosphites 5 has been prepared and employed in the synthesis of rhodium complexes of formulation [Rh(cod)(5)]BF4 (7). The use of bulky phosphane or phosphite groups in the preparation of 7 avoids the formation of undesired disubstituted complexes, one of which (9 a) has been isolated and characterized. Ligands 5 display important differences from the bulkier phosphane-phosphites 1: complexes 7-unlike their rigid [Rh(cod)(1)]BF4 counterparts-show fluxional behaviour in solution, consistent with backbone oscillation around the coordination plane. A detailed screening of ligands 1 and 5 in catalytic asymmetric hydrogenations of enol phosphonates 12 demonstrated a critical influence of the steric characteristics of the phosphane-phosphite in the course of the reaction, and optimization of the two phosphorus functionalities resulted in the production of versatile and efficient catalysts for this class of hydrogenations: enantioselectivities of up to 98% ee were thus obtained with substrates bearing an alkyl substituent in the beta-position, while for their challenging aryl counterparts values of up to 92% ee were achieved. The coordination mode of phosphonate 12 a towards a Rh phosphane-phosphite fragment has also been investigated and a preference of the olefin fragment to occupy the position cis to the phosphite group has been observed. From this observation an interpretation of the configurations of the hydrogenated phosphonates has also been made.     

Synthesis, crystal structure and luminescence properties of europium complexes with a new terpyridine-like ligand

New 1:1, 1:2 and 1:3 europium (Ⅲ) complexes with 2,4,6-tris(3,5-dimethylpyrazol-1-yl)-1, 3,5-triazine have been prepared, and their luminescence has been demonstrated to be sensitive to the π-π stacking and H-bonding interactions.     

Spectrophotometric determination of trace amounts of thallium with 7-(4,5-dimethylthiazolyl-2-azo)-8-hydroxyquinoline-5-sulphonic acid

A new reagent, 7-(4,5-dimethylthiazolyl-2-azo)-8-hydroxyquinoline-5-sulphonic acid, has been examined to evaluate its usefulness as a spectrophotometric reagent for thallium(III). A purple-red complex is formed in aqueous solution at pH 4-5 in the presence of cetylpyridinium chloride and the stoichimetric ratio is 1:2 (Tl:reagent). The apparent stability constant is 1.5 x 10(11). The effect of diverse ions has been studied and a method for determining trace amounts of thallium is proposed.     

Tritium-labeled 5-oxo-Pro-Arg-Pro

Conditions of tritium introduction into 5-oxo-Pro-Arg-Pro have been developed. Labelled 5-oxo-Pro-Arg-Pro has been obtained in 75% yield and molar radioactivity of 60 Ci/mmol. Tritium distribution over amino acid residues in the peptide has been determined. 5-Oxo-Pro : Arg : Pro ratio in the labelled peptide has been found to be 1 : 5.2 : 2.8. Nonterminal amino acid has been found to contain the major portion of tritium, about 35 Ci/mmol; i.e., arginine includes more than half of the label. Such a feature can be explained by the effect of readily protonated guanidine group of arginine. The influence of charged guanidine group of arginine seems to increase the shift of electron density in the neighboring C–H bonds of arginine and proton mobility, thus increasing protium–tritium exchange at these carbon atoms.     

Structure determination of mycolactone C via total synthesis

[structure: see text] By total synthesis, mycolactone C has been established as an approximately 1:1 mixture of Z-Delta4'5'- and E-Delta4'5'-geometric isomers of C12'-deoxymycolactones A and B.     

Synthesis and study of the structure of new N-substituted 2-methyl-5-(1-methylethyl) cyclohexylamines

Original methods of synthesizing N-substituted 2-methyl-5-(1-methylethyl)cyclohexylamines by hydroamination reactions of (+)-S-carvone with aliphatic nitriles and the hydroamination of some aldehydes and ketones with (+)-S-carvone oxime have been developed. The optimum conditions for performing these processes has been selected. It has been established by¹³C NMR that the reactions studied form a mixture of N-substituted carvo-, isocarvo-, neocarvo-, and neoisocarvomenthylamines in a ratio of 65:20:10:5. As a result of the investigation, 11 secondary amines of the p-menthane series not previously described in the literature have been isolated and characterized. The absolute configurations of the compounds synthesized have been determined.     

Kinetics of esterification of acetic acid with n-butanol over different homogeneous acid catalysts

The esterification reaction of n-butanol and acetic acid has been performed in batch reactor in the presence of different homogeneous acid catalyst, namely sulfuric acid, nitric acid, and para toluene sulfonic acid (p-TSA). The objective of present research work is to investigate kinetic behavior of esterification reaction over the temperature range of 60°C–80°C. The effect of reaction parameter such as catalyst loading varied from 1% to 5% v/v and acid to alcohol molar ratio of 1:1, 1:3, and 1:5 has been observed. A pseudo homogeneous kinetic model has been applied. Kinetic parameters such as equilibrium constant, reaction rate constant, enthalpy, activation energy, and entropy were calculated by the experimental data for different acid catalyst system. It was observed that sulfuric acid gives higher conversion 73% than p-TSA 68.5% and nitric acid 66.25% at temperature of 80°C, 1:1 molar ratio and 3% catalyst concentration. The activation energy was estimated 36448.49, 23324.31 and 19060.156 J/mol K for three different catalyst sulfuric acid, nitric acid and p-TSA respectively. The enthalpy and entropy of the esterification reaction of acetic acid with n-butanol over three different catalysts has been calculated (Enthalpy: 25.788 KJ/mol, 12.256 KJ/mol, 28.320 KJ/mol, Entropy: 88.1 J/mol K, 45.298 J/mol K, 91.44 J/mol K) and found enthalpy is having positive value that shows reaction is endothermic.