锌(Ⅱ)-邻菲咯啉络合物极谱吸附波测定微量锌

在 p H 1 0 .0 6的 0 .0 87mol L氨 氯化铵缓冲体系中 ,锌 ( ) 邻菲咯啉络合物在单扫描示波极谱仪上于 - 1 .0 6V( vs.SCE)处产生一灵敏的吸附还原波。其 2 .5次微分极谱波灵敏度高 ,波形好 ,峰峰值 epp″与锌 ( )的浓度在 4 .0× 1 0 - 8～ 2 .5× 1 0 - 6mo L 范围内呈良好的线性关系 ,其检出限为 1 .0× 1 0 - 8mol L Zn( )。该法用于微量锌测定 ,结果较好。     

络合吸附极谱波测定痕量钼

在0.05 mol.L-1HOAc-NaOAc(pH 4.74)介质中,Mo(Ⅵ)-茜素络合物在二阶导数极谱图上产生良好的吸附还原波,从而建立了络合吸附极谱法测定痕量钼的方法,其峰电位约为-0.32 V(vs.SCE)。其峰电流(I″p)与Mo(Ⅵ)浓度在8.9×10-8~2.4×10-6mol.L-1范围内呈线性关系,检出限为7.0×10-9mol.L-1。应用该法测定了茶叶、人发中痕量钼,测得回收率在98%~104%之间。研究了络合物的组成和极谱波的性质。     

钆(Ⅲ)-钙试剂络合物吸附波研究

在含有 0 .1 0 mol/L KCl,p H=1 0 .2的 NH3- NH4 Cl缓冲溶液中 ,用线性扫描示波极谱法测得 Gd( ) - Cal- red络合物有一灵敏的导数波 ,峰电位在 - 0 .84V,峰电流与钆 ( )的浓度在 1 .0× 1 0 - 7～ 5 .0× 1 0 - 6 mol/L范围内呈线性关系 ,检出限达1 .0× 1 0 - 7mol/L ;另外 ,试剂本身在 - 0 .61 V有导数极谱波 ,该波的峰电流随钆( )的浓度增加而降低 ,也具有一定的线性关系     

锌(Ⅱ)-茜素紫络合物的极谱行为及应用

用线性扫描示波极谱法研究了锌 ( ) -茜素紫络合物的伏安行为 ,发现在含有 0 .1 mol/L KCl,p H=9.96的 Britton- Robinson缓冲溶液中锌 ( ) -茜素紫络合物产生一灵敏的极谱吸附波 ,其峰电位为 - 1 .2 7V( vs.SCE) ,峰电流与锌 ( )的浓度在 8× 1 0 - 8～ 2× 1 0 - 6 mol/L的范围内呈线性关系 ,检出限为 5× 1 0 - 8mol/L。研究了电极反应机理 ,并用建立的方法成功地测定了发样中的锌     

锑(Ⅲ)-芦丁-硒(Ⅳ)体系的极谱络合吸附波研究

在 5 .0× 1 0 - 6 mol/LSe(Ⅳ )的 0 .1 2mol/L氯乙酸盐缓冲溶液 (pH 3 2 )中 ,用单扫极谱法可得到锑 (Ⅲ ) 芦丁络合物灵敏的二次导数极谱波 ,Se(Ⅳ )的存在可使锑峰峰电位正移 ,峰高增加。峰电位为 - 0 .33V(vs.SCE) ,峰高与锑(Ⅲ )的浓度在 1 .6× 1 0 - 9mol/L～ 5 .0× 1 0 - 6mol/L范围内呈线性关系 ,检出限可达 4.0× 1 0 - 1 0 mol/L。研究了极谱波的性质和电极反应机理。方法已用于锌合金中微量锑的测定     

单扫描示波极谱法测定药物中的卡托普利

报道了卡托普利 Cu+络合物的极谱吸附波。在 0 .0 2mol LH3 PO4溶液中 ,卡托普利与Cu2 +发生氧化还原反应 ,生成卡托普利 Cu+络合物 ,在单扫描示波极谱仪上于 - 0 .44V(vs.SCE)处产生一灵敏的吸附还原波。该吸附还原波二阶导数峰电流与卡托普利浓度在 1.8× 10 - 7～ 1.8× 10 - 5mol L范围内呈线性关系 ;方法的检出限为 8.0× 10 - 8mol L ;回收率在 98.0 %～ 10 3%。     

锌电解液中痕量铜、镉、镍和钴的快速同时测定

研究了丁二酮肟 氨 氯化铵 柠檬酸钠 明胶 抗坏血酸体系中Cu(Ⅱ )、Cd(Ⅱ )、Ni(Ⅱ )和Co(Ⅱ )的络合物吸附波 ,建立了同时、快速测定锌电解溶液中这些痕量元素的新方法。Cu(Ⅱ )、Cd(Ⅱ )、Ni(Ⅱ )和Co(Ⅱ )分别在 - 0 44V、- 0 76V、- 1 0 7V和 - 1 2 4V左右产生灵敏的络合物吸附波。信噪比为 3时 ,其检测限分别为 1 0× 1 0 - 8mol/L、1 3× 1 0 - 8mol/L、2 9× 1 0 - 1 0 mol/L和 3 6×1 0 - 1 1 mol/L。铜、镉、镍和钴的浓度分别为 2 0× 1 0 - 8mol/L～ 2 0× 1 0 - 5 mol/L、3 0× 1 0 - 8mol/L～ 3 0× 1 0 - 5mol/L、5 4× 1 0 - 1 0 mol/L～ 5 4× 1 0 - 7mol/L和 6 8× 1 0 - 1 1 mol/L～ 6 8× 1 0 - 8mol/L时 ,与相应峰电流之间有良好的线性关系。方法已用于锌电解液中铜、镉、镍和钴的快速同时测定 ,相对标准偏差分别小于或等于 4 7%、5 1 %、4 9%和 5 3 %。     

示波极地测定车间空气及其周围大气中的锡

用示波极谱法测定了焊锡车间空气及其周围大气中的锡。在 p H 2 .5的0 .1mol/ L 氯乙酸介质中 ,Sn( )与焦没食子酸形成的络合物在汞电极上还原可分别在 -0 .2 5 V和 -0 .45 V各产生一峰形良好的还原波。当有四价钒存在时 ,-0 .45 V处的波的峰电流大幅度增大 ,产生一灵敏的催化电流。该催化电流与锡浓度在 1× 10 -8～ 5× 10 -7mol/ L 范围内呈线性关系 ,检测限为 5× 10 -9mol/ L     

泼尼松的示波极谱测定及其电化学行为

基于泼尼松产生的极谱还原波 ,提出了测定泼尼松的单扫描示波极谱法。在0 .1 2 mol/ L HAc-0 .0 8mol/ L Na Ac ( p H 4.6)的缓冲溶液中 ,泼尼松于 -1 .1 3 V处产生一极谱还原波。二阶导数峰电流与其浓度在 2 .4× 1 0 - 6～ 1 .6× 1 0 - 5mol/ L范围内有良好的线性关系 ( r=0 .9991 ,n=8) ,检出限为 8.0× 1 0 - 7mol/ L。测定了片剂中泼尼松的含量。讨论了泼尼松的电化学行为     

铑-丁二酮肟络合吸附波测定微量铑

在pH 4.3 0的醋酸 醋酸钠支持电解质中 ,铑和丁二酮肟 (DMG)生成具有电活性络合物。在单扫示波极谱 -1 .0 6V (vs.SCE)左右出现良好的极谱还原波 ,实验表明此波属络合吸附波。此波二阶导数峰高与铑的浓度在 1 .5× 1 0 - 8～ 1 .9× 1 0 - 7mol/L和 1 .9× 1 0 - 7～ 3 .9× 1 0 - 6 mol/L范围内呈线性关系 ;检出限为 4.9× 1 0 - 9mol/L方法 ,可用于铑的测定 ,并成功的用于贵金属合成样及合金样品中铑含量的测定。     

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.     

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.