桑色素修饰碳糊电极吸附溶出伏安法测定人尿中痕量铅

制作了用桑色素作修饰剂的碳糊修饰电极 ,利用该电极为工作电极 ,建立了测定痕量铅的新方法。在甲酸钠 盐酸缓冲溶液 (pH 4 .9)中 ,在 - 0 .10V(vs .SCE)下搅拌富集 ,铅 (Ⅱ )与化学修饰碳糊电极表面的桑色素形成电活性络合物而吸附富集于电极表面 ,经 - 0 .85V(vs.SCE)静止还原后 ,阳极化线性扫描 ,在 - 0 .4 3V(vs .SCE)获得一灵敏的二次导数溶出峰。在最佳条件下分别富集 360s和 180s ,其二次导数峰电流与铅 (Ⅱ )浓度分别在 5 .0× 10 - 9～ 1.0× 10 - 7mol·L- 1和 2 0×10 - 8～ 1.0× 10 - 6 mol·L- 1两个范围内呈良好的线性关系 ,富集 6min ,检出限可达 1.0× 10 - 9mol·L- 1(S/N =3)。同时 ,探讨了电极反应机理。方法应用于尿铅测定 ,获得满意的结果     

2-羟基-3-(三乙胺基)丙基十烷基硫醚修饰电极测定痕量金

研究了 2 羟基 3 (三乙胺基 )丙基十烷基硫醚 (HTPSD)修饰玻碳电极测定金的伏安特性及分析条件。在 0 .2mol·L- 1KCl HCl缓冲溶液中 (pH 1) ,金 (Ⅲ )被富集到电极表面 ,然后介质交换到 0 .2mol·L- 1KCl HCl空白溶液中 (pH 1)进行阴极溶出伏安测定 ,金 (Ⅲ )浓度在 2× 10 - 81× 10 - 6mol·L- 1范围内呈线性关系。检出限为 1× 10 - 8mol·L- 1。相对标准偏差小于 6 2 % ,一般常见离子不干扰。     

肌红蛋白在磷脂-月桂酸修饰的玻碳电极上的电化学行为及其分析应用

报道了肌红蛋白(Mb)在磷脂、月桂酸修饰的玻碳电极上的电化学行为 ,在 +0.2～ -0.7V(vs.Ag/AgCl)电位范围内 ,于pH6.0的0.01mol·L-1的KH2PO4、Na2HPO4底液中 ,肌红蛋白产生不可逆的还原电流峰 ;还原峰电流与肌红蛋白浓度在2.25×10-8 ～1.40×10-6 mol·L-1 范围内呈良好线性关系 ;线性回归方程为Ip(μA)=-0.01419 +0.2382cMb(10 -7mol·L -1) ,线性回归系数r(10)为0.998 ,检出限为1.20×10 -8mol·L -1,该电极可作为检测肌红蛋白的新型的高灵敏度电化学生物传感器。     

磷钼钒杂多酸-聚吡咯膜修饰电极测定污水中亚硝酸根离子

采用电化学方法在导电基体玻碳电极上制备出磷钼钒杂多酸-聚吡咯膜修饰电极,研究了NO-2在该电极上的电化学行为。结果表明,磷钼钒杂多酸-聚吡咯膜修饰电极对酸性水溶液中的NO-2具有良好的电催化还原作用,与空白玻碳电极相比。降低过电位1000mV以上,而且N0-2的浓度在5.0×10-6～1.0×10-2mol·L-1范围内,催化峰电流与NO-2浓度呈良好的线性关系,检出限可达1.0×10-6mol·L-1,用于环境水中NO-2的测定,结果良好。     

利用新型汞离子选择电极测定污水中汞(Ⅱ)

报道了一种以苯海拉明与碘汞酸盐缔合物为电活性物的新型聚氯乙烯膜汞离子选择电极 ,电极的线性响应范围为 1.0× 10 - 2 1.6× 10 - 5mol·L- 1,级差为 2 9mV·pC- 1,检出限为 1.0×10 - 5mol·L- 1。该电极响应迅速 ,重现性好 ,用此电极以标准曲线法对污水中的Hg(Ⅱ )进行了测定 ,方法简便 ,结果满意     

丝网印刷普鲁士蓝修饰电极催化还原测定过氧化氢

制备了普鲁士蓝修饰的丝网印刷过氧化氢传感器,研究了过氧化氢在该修饰电极上的电催化还原特性,考察了有关修饰膜制备和试验条件对传感器性能的影响。结果表明,pH4.0的0.2mol·L-1KH2PO4 K2HPO4缓冲溶液(PBS)中,修饰电极对过氧化氢显示出快速的电化学响应,较高的稳定性、重现性和催化活性,测定的线性范围为1.0×10-5～1.0×10-3mol·L-1,相关系数为0.999,检出限为6.0×10-6mol·L-1(3σ)。电极制作方法简便,可用于实际样品的测定。     

L-半胱氨酸自组装膜电极的表征及其对对苯二酚的差分脉冲伏安法测定

研究了 L-半胱氨酸自组装膜修饰金电极 ( L - Cys Au/SAMs)催化对苯二酚氧化的电化学行为 ,发现该膜电极大大降低了对苯二酚的氧化电位。采用水平衰减全反射 ( ATR) FTIR光谱技术和 K3Fe( CN) 6 电化学探针对 L- Cys Au/SAMs进行了表征。用差分脉冲伏安法 ( DPV)测定其氧化峰电流与对苯二酚的浓度在 2 .0× 1 0 - 6～ 2 .0× 1 0 - 4mol· L- 1范围内呈良好的线性关系 ,相关系数 0 .9986,检出限 4.0×1 0 - 7mol·L- 1。该电极用于模拟废水样的测定 ,结果满意。     

钴-锌试剂络合吸附伏安法测定中草药中钴

研究了测定痕量钴的一种灵敏的吸附伏安法 ,利用钴和锌试剂络合物在悬汞电极上的吸附性 ,有效地提高了分析的灵敏度。在 0 .0 0 5mol·L-1NH3 和 0 .0 6mol·L-1NH4Cl及 2 .5× 1 0 -6mol·L-1锌试剂底液条件下 ,该体系 1 .5 ,2 .5阶微分吸附伏安法测定钴的线性范围为 1× 1 0 -10 ～ 1× 1 0 -7mol·L-1,用 2 .5阶微分吸附伏安法 ,富集 3min的检出限为 5× 1 0 -11mol·L-1。用此法直接测定了中草药中痕量钴     

邻苯三酚红修饰碳糊电极吸附伏安法测定痕量铜

报道了采用邻苯三酚红修饰碳糊电极测定痕量铜的方法。通过在邻苯二甲酸氢钾 -氢氧化钠 (p H4.5)介质中富集 ,Cu2 +和邻苯三酚红形成络合物富集于电极表面 ,然后转换到 0 .0 50 mol· L-1的 H3PO4 中 ,经阴极还原后再进行阳极溶出伏安法测定。Cu2 +浓度在 1 .6× 1 0 -9～ 2 .8× 1 0 -7mol·L-1范围内与二次导数峰电流呈线性关系 ,检出限达 8× 1 0 -10 mol·L-1。同时 ,对电极反应机理进行了探讨。应用于合金样的测定 ,取得满意的结果。     

钴氢氧化物修饰玻碳电极的镀膜/循环伏安法制备及其电化学行为

采用一种新方法镀膜 /循环伏安法成功制备了钴氢氧化物修饰玻碳电极 .考察了影响钴氢氧化物膜电催化活性的因素 ,确定最佳富集时间为 2min ,最佳活性单元浓度为 9 90× 10 -4mol·L-1.讨论了成膜过程及机理 .膜氧化峰电流 (i0pa)与扫描速率 (v <0 60V·s-1)成正比 ,具有表面吸附反应特征 ,表面覆盖量约相当于 0 5个单层的氧化还原活性物质 .制得的钴氢氧化物膜修饰电极具有相当的稳定性 ,并对H2 O2 氧化表现出较高的电催化活性 .线性回归方程为 :Δipa( μA) =-2 10 3 6+2 3 72 0× 10 4CH2 O2 (mol·L-1) (R =0 9990 ,n =18) ,线性范围为 :1 43× 10 -5～ 1 80× 10 -2 mol·L-1,检出限为 :9 5 9× 10 -6mol·L-1( 3S/k) .     

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.