测定尿中痕量碘的高锰酸钾-亚砷酸体系催化光度法

在硫酸和磷酸的介质中,碘离子催化高猛酸钾与亚砷酸反应生成的锰（Ⅲ）氧化砷酸的反应,据此建立了催化光度法测定痕量碘的新方法。该法的检出限为0．4μg/L,测定的线性范围为1．0－25．0μg/L。应用该法测定了尿样中痕量碘的含量,获得了满意的结果,测定样品的相对标准偏差（n＝6）为2．5％－3．7％,加标回收率为96．4％－102．6％。     

废水中痕量酚的流动注射停流-催化光度法测定

基于在硫酸介质中痕量酚对溴酸钾氧化罗丹明B反应的催化作用,建立了测定痕量酚的快速、简便的流动注射流－催化光度分析的新方法。该方法的线性范围为0．60－4．00mg/L,检出限为0．1mg/L,进样频率为34／h。11次重得测定的相对标准偏差小于2．0％。该法用于废水中酚的测定,并与4－氨基安替比林比色法对照,结果满意。     

催化动力学电位法测定痕量亚硝酸根

基于稀硫酸介质中，亚硝酸根对溴酸钾氧化碘化钾有催化作用，用碘离子选择电跟踪I^-，建立了测定痕量亚硝酸根的催化动力学电位法。在适宜条件下，该指示反应为一级反应，反应速度可用电位的变化（ΔE）表示。当时间固定时，ΔE与亚硝酸根浓度在0－0．12mg/L范围内呈线性关系，检出限为2．0μg/L。该法用于水样中痕量亚硝酸根的测定，结果满意。     

顺序注射催化动力学光度法测定废水中的痕量酚

在硫酸介质中,利用酚催化溴酸钠氧化桔花青的反应,联用顺序注射技术建立了顺序注射催化动力学光度法测定废水中痕量酚的新方法。方法的线性范围0．4—3．5mg／L,检出限0．1mg／L。该法测定快速简便,常见共存物干扰小,消耗试剂量小,减少了二次污染,用于工业废水中的痕量酚的测定,并与4-氨基安替比林比色法对照,结果无显著差异。     

阻抑聚丙烯酰胺催化蛋白质-亚甲基蓝褪色光度法测定痕量铋

在加热条件下，基于Bi（Ⅲ）对聚丙烯酰胺（PAM）催化蛋白－亚甲基蓝（MB）褪色反应有强的抑制作用，建立了动力学光度法测定铋的新方法。△A与CBi(Ⅲ）呈线性关系的范围为0．08－0．48μg/L；检出限为0．004μg/L；对0．04和0．040μgBi(Ⅲ）／L测定的RSD分别为6．4％一2．6％，本阻抑－催化褪色反应对Bi(Ⅲ）、蛋白质－亚甲基蓝和PAM为一级反应，表观活化能为49．22kJ/mol.该方法已用于某些谷物，人发和水样中Bi(Ⅲ）的测定。结果满意。     

流动注射催化光度法测定化探样品中痕量钒

利用痕量钒对铍试剂Ⅲ-抗坏血酸体系的催化作用，建立了一个流动注射-分光光度法测定化探样品中痕量钒的方法。该方法具有灵敏度高，分析速度快的特点。选择反应温度为90℃时，反应速度加快，测量时间由普通光度法1h减少到约1min，分析速度为60样次／h。方法的检测限为7μg／L，对于含钒0．4mg／L的试样,RSD为0．6％（n＝30），用于化探样品，分析结果满意。     

萃取催化光度法间接测定痕量抗坏血酸

研究了在pH5.5的HAc NaAc缓冲溶液介质中,利用抗坏血酸活化Fe(Ⅲ)催化H2O2氧化邻氨基酚的显色反应,用萃取平衡控制反应时间和水相中邻氨基酚的浓度及反应程度,通过测量424nm下有机相的吸光度,建立了萃取催化光度法间接测定痕量抗坏血酸的新方法。方法的线性范围为0～50.0μg/L,检出限为6.7×10-7g/L。方法可用于维生素C片和西红柿中抗坏血酸的测定。并对反应机理进行了探讨。     

亚甲基蓝荧光猝灭法测定抗坏血酸

在稀H2SO4介质中,抗坏血酸与亚甲基蓝发生反应,使其荧光猝灭,建立了荧光光度法测定痕量抗坏血酸的新方法,用正交法确定最佳测定条件。方法的激发波长为660 nm,发射波长为694 nm,在最佳条件下该法测定抗坏血酸的线性范围为0.1~40 mg/L,检出限为0.23 mg/L。方法可用于药品、饮料、果蔬中抗坏血酸的测定。     

以盐酸肼还原劳氏紫催化动力学光度法测定痕量钼

研究了在盐酸介质中,钼（Ⅵ）催化盐酸肼还原劳氏紫使之褪色的新指示反应,确定了催化褪色反应测定钼（Ⅵ）的动力学条件,考察了30种共存离子对测定的影响。钼（Ⅵ）的浓度在0－0．34mg/L范围内工作曲线呈良好的线性关系,方法的表现摩尔吸收系数为1．3×105L·mol－1·cm－1,最低检出限为6．23×10－9g/mL。该方法已用于实际样品的测定,相对标准偏差为2．4％－3．1％,标准加入回收率为96．0％－106％,结果令人满意。     

灿烂甲酚蓝褪色光度法测定抗坏血酸

在pH2的HCl缓冲溶液和增敏剂对氨基苯磺酸存在下，抗坏血酸还原灿烂甲酚蓝并使之褪色，褪色反应的体系具有很好的稳定性。在最佳的反应条件下，建立了测定抗坏血酸的新方法，该方法的检出限为0．28mg/L，对0．40mg/L的抗坏血酸测定的RSD为1．2％(n＝11)，线性范围为0．24-32mg/L，方法可应用于药品、合成样品中抗坏血酸的测定。     

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.     

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.     

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.