火焰原子吸收分光光度法测定铜合金中的铁

研究了火焰原子吸收分光光度法测定铜合金中铁含量的方法,对仪器工作条件如灯电流、光谱通带、空气和乙炔流量进行了分析。铁的质量浓度在0-5mg／L内与吸光度呈良好的线性关系,线性方程为A：0．03179c＋0．004098,相关系数,r=0．9996,检出限为0．009mg／L。用该方法对4种铜合金标准物质进行测定,测定结果与标准值相符,相对标准偏差分别为0．54％,0．78％,0．10％,2．07％0=6）。     

蒸馏分离-分光光度法测定枸杞子中的微量锗

利用盐酸与锗元素反应生成易挥发的四氯化锗，以蒸馏方法将四氯化锗分离出来，然后在1～1．5mol／L盐酸溶液中，用显色剂苯芴酮与四氯化锗进行显色反应生成橙红色配合物，在500nm波长处进行分光光度法测定。在0～200μg／(50mL)，线性方程为A=0．1714c．相关系数r=0．9996。该方法的检出限为0．0588μg／mL，测定结果的相对标；位偏差为2．24%～2．30%(n=11)，平均回收率为95．3％～95．4％。     

锌试剂分光光度法测定壳聚糖含量

利用锌试剂与壳聚糖在一定酸度条件下的特异性显色反应，即其复合物在465nm处吸光度与壳聚糖含量在0～O．04g／L范围内呈现良好的线性关系(R=0．996)，基于此建立了一种简便快速的分光光度法。平均回收率为99．68％。     

反相流动注射-化学发光法测定氢化可的松

在碱性介质中,氢化可的松可被Fe(CN)6^3-氧化产生化学发光,奎宁对此发光反应有显著的增敏作用。据此,建立了反相流动注射-化学发光法测定氢化可的松的新方法。方法的线性范围和检出限分别为0．05．-50mg／L和0．02mg／L,相对标准偏差(n=11,C=1．0mg／L)为0．9％。方法用于药物中氢化可的松含量的测定,结果与标准方法分光光度法测定结果吻合。     

怀菊花中微量铁的测定

为探讨邻二氮菲分光光度法测定怀菊花中微量元素铁含量的可行性,怀菊花的药理功效、食用营养价值与微量元素含量可能存在的关系,根据铁离子与特定显色剂显色产生可见吸收,采用混合酸y（HNO3）：V（HClO4）=4＋1对怀菊花样品湿法消化处理,在pH2～9的溶液中试剂与铁生成稳定的橙色络合物,并用分光光度法测定了怀菊花中微量元素铁含量。结果表明,所选的怀菊花中铁含量303．9～337．9μg／g,加标回收率为90．2％～100．6％。分光光度法操作简便、干扰离子少,测量快速、结果准确度和灵敏度高,易推广和 普及使用。     

生物样品中Se的荧光测定方法

运用微波消化系统处理生物样品，以2，3-二氨基萘为荧光试剂建立了一种测定生物样品中Se的荧光分光光度法。方法的最低检出限为1．6ng／mL，线性范围0～0．600μg／mL，回收率92．22％～99．78％，连续10次测定样品变异系数（CV）为0．4％（n=10），隔213重复实验变异系数为1．54％。该法具有灵敏、稳定、可靠等优点，适用于生物样品中Se含量的测定。     

双硫腙加OP乳化剂直接比色法测定废水中的镉

利用聚氧乙烯烷基酚醚类（俗称OP乳化剂）的增色增溶作用,用双硫腙加OP乳化剂直接比色法测定废水中的镉。在0-5μg／mL范围内,镉浓度与吸光度线性相关,相关系数为0.999。方法的相对标准偏差为1.5％（n=5）,样品加标回收率为98.0％-101.9％。该法与国标GB7471-1987双硫腙分光光度法比较,操作简便、无毒性。     

石墨炉原子吸收分光光度法测定大气颗粒物中的镉

将大气颗粒物样品采集在有机滤膜上(或滤筒中)，用硝酸、高氯酸消解，以石墨炉原子吸收分光光度法测定其中镉的含量。在0．00～8．00μg/L范围内对镉的质量浓度与吸光度数据进行回归，得线性方程为A：0．016 0．041X，相关系数r=0．9991，回收率为90％～94％，测定结果的相对标准偏差为2．1％～7．5％，检出限为0．366μg/L，该方法适用于大气和固定污染源排气中镉的测定。     

流动注射分光光度法测定工业废水中的钼

将流动注射分析技术与硫氰酸盐分光光度法相结合,建立了测定工业废水中钼的快速分析方法。在采样频率为80样／h时,检出限为0．08mg／L,线性范围为0—10mg／L。应用该方法测定工业废水样中的钼含量,相对标准偏差不大于1．3％（n=5）,加标回收率为96．6％～98．1％,测定结果与采用国家标准方法测定结果基本一致。     

荧光红-曙红Y能量转移及荧光猝灭法测定痕量铜(Ⅱ)的研究

在λex／λem=404．7／550nm,乳化剂OP存在下,荧光红-曙红Y能够发生有效能量转移,使曙红Y荧光强度大大提高;在pH6．5～7．6的KH2PO4-NaOH缓冲溶液中,Cu(Ⅱ)与曙红Y和邻菲罗啉形成配合物,使曙红Y的荧光猝灭,从而建立了测定痕量铜的荧光分析新方法。铜含量在0～250μg／L范围内与曙红Y的荧光猝灭程度呈良好的线性关系。方法的检出限为0．82μg／L;测定100μg／L铜溶液,其RSD为4．6％(n=11);样品加标回收率为102．1％～105％。本法用于人发、茶叶和大米中痕量铜的测定,结果满意。     

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.