In(Ⅲ)-1-苯基-3-甲基-4-噻吩甲酰基-吡唑啉酮-5配合物吸附波的研究

在pH3.0的HCl-NaAc介质中,In(Ⅲ)与1_苯基_3_甲基_4_噻吩甲酰基_吡唑啉酮_5(HPMTHP)生成配合物,于-0.63V(vs.SCE)处出现一尖锐、灵敏的极谱峰,In含量在0.002～1μg/mL范围内与峰高呈线性关系。用多种电化学方法研究了极谱波的性质及反应机理,证明-0.63V处的极谱波为配合物吸附波,峰电流由中心离子In(Ⅲ)还原产生。用直线法测得配合物组成为n[In(Ⅲ)]∶n(HPMTHP)=1∶1,表观稳定常数为2.96×103。     

铑(Ⅲ)与5-(5-硝基-2-吡啶偶氮)-2,4-二氨基甲苯的极谱催化氢波研究

本文研究了铑( )与5-(5-硝基-2-吡啶偶氮)-2,4-二氨基甲苯(5-NO2-PADAT)配合物的极谱行为,发现在pH=5.00HAc-NaAc缓冲溶液中,配合物于-1.20V(vs.SCE)处产生一灵敏的极谱催化氢波。基于此,建立了测定痕量铑的新方法。该催化氢波峰电流i′p与铑( )浓度在2.0×10-3～1.8×10-2μg/mL范围内呈线性关系,检出限为1.0×10-3μg/mL。研究了该催化氢波的性质及其反应机理。     

W(Ⅵ)-二苯基乙醇酸-2,2′-联吡啶极谱波研究及应用于岩溶地下水分析

在0.05 mol/L硫酸溶液中,W(Ⅵ)与二苯基乙醇酸络合在-0.70 V(vs.SCE)产生一灵敏的阴极极谱催化波,体系中加入2,2′-联吡啶后,W(Ⅵ)配合物的极谱波明显增高,峰电位负移到-0.80 V,标准曲线斜率变大,体系的稳定性显著提高。W(Ⅵ)在0.02~50 ng/mL范围与峰高呈良好线性关系,检出限达1.8×10-11mol/L。实验确定了最佳条件,拟定了不经分离富集直接测定岩溶地下水中痕量钨的方法。此外对极谱波的性质进行了探讨,证明该极谱波为配合物吸附催化氢波,讨论了阳离子表面活性物质对催化氢波的影响及相关作用机理。     

极谱法测定毒死蜱等有机磷农药残留

建立了测定毒死蜱、辛硫磷、乐果、水胺硫磷和三唑磷5种常见有机磷农药残留的极谱分析新方法。优化实验条件下,毒死蜱浓度在0.0192~24.0μg/mL范围内与峰电流成线性关系,检出限为0.012μg/mL,回收率在90.36%~103.3%范围。其它有机磷农药的线性范围分别为:辛硫磷0.016~25.2μg/mL,乐果13.41~33.52μg/mL,水胺硫磷为17.42~34.84μg/mL,三唑磷为0.0110~21.2μg/mL。用极谱法研究了毒死蜱的电化学行为,证明了电极反应物为水杨基荧光酮,极谱波为不可逆还原吸附波。     

铅镉-邻菲啰啉-溴化钾配合物的吸附波及其应用

作者发现,在pH3.2的盐酸-醋酸钠缓冲溶液中,铅和镉与邻菲啰啉、溴化钾形成的多元配合物分别于-0.50V和-0.71V(VS.SCE)处产生灵敏的吸附波。铅和镉的检测下限分别为0.002μg/ml和0.0005μg/ml。研究表明,该波具有吸附性质。本法可用于连续测定天然水和废水中的痕量铅、镉。     

萃取光度法测定电镀废水中微量镉

采用双硫腙-TBP萃取光度法快速测定电镀废水中微量镉。在磷酸盐的中性缓冲溶液中,双硫腙-TBP显绿色,与镉离子生成橙红色配合物。镀镉废水中的干扰离子用钛铁试剂-酒石酸钾钠-碘化钾联合掩蔽。镉-双硫腙配合物萃取至有机相直接进行光度法测定。试验结果表明,在500 nm波长处,表观摩尔吸光系数为6.0×104L.mol-1.cm-1,Sandell灵敏度为0.001 9μg.cm-2;5 mL有机萃取相中镉含量在0~8.0μg/5 mL符合比耳定律。应用电镀废水样品中微量镉的直接萃取测定,分析结果的相对偏差小于2.8%,回收率为99.5%。     

锡-茜素氨羧络合剂络合吸附波的研究罐头食品中微量锡的测定

在pH4.6的0.5mol/L HAc-NaAc缓冲液中,Sn(Ⅳ)-ALC配合物在2.5次微分极谱仪上产生一良好的吸附还原波,其峰电位为-0.70V(vs.SCE),峰电流与锡浓度在0.01～0.5μg/mL范围内呈线性关系,检测下限0.001μg/mL。对其电极过程进行了探讨,并用该法测定了食品罐头中的微量锡。     

铬(IV)-4-氨基安替吡啉配合物极谱波的研究

我们发现铬(VI)的显色剂-4-氨基安替吡啉与铬(VI)形成的配合物, 在亚硝酸钠氨性底液中(pH~9), 单扫描极谱仪上有一灵敏而又波形良好的配合物吸附催化波.检测下限为4X10-9g/mL, 铬(VI)浓度在6X10-9~8X10-8g/mL 范围内, 峰高与浓度成正比. 本文对该波的极谱性质作了初步探讨, 对测定铬(VI)的最佳条件进行了讨论. 利用该法我们测定了废水及茶叶中的微量铬, 标准偏差0.15, 变动系数7.1%, 回收率96%.     

1-(4-硝基苯基)-3-(2-吡嗪)-三氮烯的合成及与镉(Ⅱ)的显色反应

报道了显色剂1-(4-硝基苯基)-3-(2-吡嗪)-三氮烯化合物的合成及其与镉(Ⅱ)的显色反应。在非离子表面活性剂Triton X-100存在下,pH 10.5的Na2B4O7-NaOH的缓冲介质中,该试剂能与镉(Ⅱ)与发生显色反应,形成摩尔比为4∶1的黄棕色配合物,配合物在波长453 nm处有最大吸收峰,表观摩尔吸光系数ε为6.90×104L.mol-1.cm-1,镉(Ⅱ)质量浓度在0~0.56μg/mL范围内遵守比尔定律。用拟定方法测不同废水中的镉(Ⅱ)。     

萘丁美酮的极谱波特征及其分析应用

在NaH2PO4-Na2HPO4(pH=9.0)缓冲溶液中,萘丁美酮在-0.62V处产生一个灵敏的极谱波.导数波高与萘丁美酮的浓度在0.5～25.0μg/mL范围内呈良好的线性关系,检出限为0.06μg/mL.通过对萘丁美酮的极谱波行为的分析,探讨了电极反应机理,建立了测定微量萘丁美酮的分析方法.     

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.