催化褪色光度法测定痕量钴的研究

研究了在ＰＨ１０．５的Ｎａ２Ｂ４Ｏ７－ＮａＯＨ介质中，痕量钴（Ⅱ）对过氧化氢氧化桑色素初色反应的催化作用，建立了催化动力学光度法测定痕量钴的新方法。方法的线性范围为０－１．２μ／ｍＬ检出限为４．４＊１０＾－１８ｇ／Ｌ。用于水和维生素Ｂ１２中钴的测定，结果满意。     

钴(Ⅱ)-三溴偶氮胂-高碘酸钾体系催化分光光度法测定痕量钴

在硫酸介质中，钴（Ⅱ）对高碘酸钾氧化三溴偶氮胂褪色有明显的催化作用，据此建立了测定水样中痕量钴（Ⅱ）的新方法．测定的线性范围为０～１．０μｇ／２５ｍＬ，检出限为６．８×１０－１０ｇｍＬ－１．     

二溴硝基偶氮氯膦催化动力学光度法测定痕量钴的研究

研究了在ｐＨ７．０磷酸盐介质中，钴催化Ｈ２Ｏ２氧化二溴硝基偶氮氯膦色反应，建立了催化光度法测定痕量钴的新方法，其检出限为５×１０＾－７ｇ／Ｌ，在０．５－３２μｇ／Ｌ范围内，钴与ｌｇ呈良好的关系。     

溴酸钾氧化中性红催化光度法测定NO-2的研究

研究了盐酸介质中,痕量亚硝酸根催化溴酸钾氧化中性红褪色反应及其动力学条件,建立了催化动力学光度法测定痕量亚硝酸根的新方法,ＮＯ＾－２的测定线性范围为１－７μｇ／２５ｍｌ,检出限为１．５＊１０＾－８ｇ．ｍｌ＾－１。用于化学试剂及唾液中痕量ＮＯ＾－２的测定,结果满意。     

钴(Ⅱ)催化偶氮胭脂红B的褪色反应特性及应用

基于氢氧内介质中痕量钴对过氧化氢氧化偶氮胭脂红Ｂ的褪色反应的强烈催化作用,建立了催化光度法测定痕量钴的新方法。方法灵敏度为５．２４×１０＾－１２ｇ／ｍＬ,测定范围为０￣３５ｎｇ／１０ｍＬ,对质量浓度为３μｇ／Ｌ的Ｃｏ（Ⅱ）重复测定１１次的相对标准偏差为２．１６％。方法应用于维生素Ｂ１２和矿泉水中痕量钴的测定,结果满意。     

重铬酸钾氧化偶氮胂Ⅲ褪色催化光度法测定痕量钴的研究

在醋酸－醋酸钠缓冲介质中痕量钴（Ⅱ）对重铬酸钾氧化偶氮胂Ⅲ褪色反应有显著的催化作用，催化反应的表现活化能为２５．６２ｋＪ．ｍｏｌ＾－１，据此建立了测定痕量钴的催化动力学分析法，线性范围为０～３５０ｎｇ．ｍＬ＾－１，检出限为２．０ｎｇ．ｍＬ＾－１（Ｃｏ），除Ｆｅ（Ⅱ）外，其余常见共存离子基本不影响钴的测定，本法重现性较好，用于测定人发，茶叶，土壤和废水中钴的含量，结果满意。     

过氧化氢氧化二甲苯蓝AS催化光度法测定痕量钴的研究

研究了在碱性条件下,痕量钴（Ⅱ） 与三乙醇胺协同催化Ｈ２Ｏ２氧化二甲苯蓝ＡＳ指示反应的动力学行为,建立了测定痕量钴的新催化动力学分析法。质量浓度的线性范围为０～２．９ μｇ／２５ ｍ Ｌ,检出限为１．３×１０－ ７ ｇ／Ｌ。讨论了催化反应机理,测定了茶叶、人发等样品中钴的含量。     

邻联甲苯胺-过氧化氢催化光度法测定钴

１引言 在碱性介质中,痕量Ｃｏ（Ⅱ）见对Ｈ２Ｑ２氧化邻联甲苯胺（ｏ－Ｔｏｌｉｄｉｎｅ）的显色反应具有强烈的催化作用,探讨了利用该反应进行痕量Ｃｏ（Ⅱ）测定的影响因素,建立了测定痕量Ｃｏ（Ⅱ）的催化动力学光度法,该方法的灵敏度为１．７８ × １０－６ｇ／Ｌ,测定的线性范围为０．８～３．６ μｇ／Ｌ Ｃｏ２＋,应用于维生素Ｂ１２中痕量Ｃｏ（Ⅱ）的测定,结果满意。２实验部分２．１仪器与试剂 ７２１－１００型分光光度计;电热恒温水浴槽;Ｎｉｃｏｌｅｔ ＦＴ－ＩＲ ５ＤＸ红外光谱仪。钴（Ⅱ）标准溶液：１ｍｇ／Ｌ;…     

测定钴的化学发光新体系

研究了新吖啶衍生物９，１０－二甲基吖啶氟磺酸盐的化学发光特性。建立了测定Ｃｏ６２＋的化学发光新体系。方法线性范围为１．０×１０＾－１０－１．０×１０＾－７ｇ／ｍＬ；检测限为５．０×１０＾－１１ｇ／ｍＬＣｏ＾２＋。测定５．０×１０＾－９ｇ／ｍＬＣｏ６２＋的相对标准偏差为６．０％。方法选择性好，用于自来水，江水，池塘水中痕量钴的测定，结果令人满意。     

以β—环糊精为增敏剂催化光度法测定锰

基于β－环糊精作增敏剂，锰催化高碘酸钾氧化靛红的反应，拟定了测量痕量锰的新催化光度法。由于添加了β－环糊精，灵敏度提高了２１倍和５９倍。相对标准偏差为２．５％，检出限为１．１×１０＾－１０ｇ．ｍＬ＾－１，可用于铝合金名锰的测定，初步探讨了有关反应机理。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.