石墨烯修饰玻碳电极伏安法测定美洛昔康

通过在玻碳电极表面电化学还原氧化石墨烯的方法制备了石墨烯修饰电极,研究了美洛昔康在该修饰电极上的电化学行为。优化了包括支持电解质及pH、修饰剂用量、富集电位及时间等测定条件,据此建立了一种直接测定美洛昔康的电化学分析方法。在0.1 mol/L Britton-Robinson缓冲液(pH 3.0)中,氧化峰电流与美洛昔康浓度在1.0×10-6～8.0×10-5mol/L范围内呈现良好的线性关系,检出限为3.0×10-7mol/L(S/N=3)。方法可用于片剂和尿样中美洛昔康的测定。     

同步扫描荧光法测定美洛昔康片的含量

基于美洛昔康与浓硫酸反应后的水解产物的荧光性质,建立了一种利用同步扫描技术测量美洛昔康片剂含量的荧光光度分析方法,考察了硫酸的用量及反应时间,表面活性剂等条件对产物荧光性质的影响.方法检出限为1.9×10-9mol/L,同步荧光峰强度与美洛昔康浓度在6.0×10-8-1.0×10-5mol/L范围内呈良好的线性关系.利用本法测定片剂中美洛昔康的含量,平均回收率为97.1%(RSD=1.5%,n=9).     

FLUORIMETRIC DETERMINATION OF TETRACYCLINE IN SERUM AND URINE

The Eu-Tetracycline(TC)-TOPO-sodium dodecyl sulfonate(SDS)system wasstudied,Experiments showed that the maximum fluorescence intensity was obtainedin the pH range of 7.5-8.7 and the concentrations of Eu~(a+),TOPO and SDS are1.0×10~(-6)mol/L,1.0×10~(-8)mol/L and 1.0×10~(-8)mol/L,respectively,This fluorescencesystem can be used for the determination of TC in serum and urine,Beer's Law isobeyed in the range of 2.0×10~(-8)mol/L=1.0×10~(-6)mol/L for the concentration of TC.The determination limit is 1.2×10~(-8)mol/L,The composition and the luminescencemechanism were discussed.     

紫草素的电化学研究

建立了测定紫草素的单扫描极谱分析方法;在0.03mol/LNa2CO3+0.2mol/LNaOH(pH=12.63)底液中,紫草素于-0.60V(SCE)处有一灵敏的二次导数还原峰,电流峰高与浓度在7.0×10-8～5.6×10-7mol/L和6.0×10-7～4.2×10-5mol/L范围内呈线性关系,检出限为3.5×10-8mol/L;用于中药紫草中紫草素的测定,结果良好;同时还研究了紫草素的电极反应机理.     

化学发光法测定氧氟沙星的含量

利用氧氟沙星对碱性Luminol H2O2 化学发光体系的增敏作用,建立了一种测定氧氟沙星的新方法。方法的线性范围为5.53×10-9 ~2.21×10-5 mol/L,检出限(3σ)为5.08×10-10 mol/L,RSD为2.23%(cs=1.38×10-5 mol/L,n=8)。该法用于针剂、片剂及胶囊中氧氟沙星含量的测定,结果令人满意。     

铋-N-苯甲酰苯胲络合吸附波的研究

在pH5.6的0.2mol/L NH_4Ac-3×10~(14)mol/L N-苯甲酰苯胲(N-BPHA)底液中,用单扫示波极谱法可得到Bi(Ⅲ)的络合物吸附波,峰电位-0.33V(vs.SCE)左右。导数峰高与铋的浓度在5.0×10~(-8)～4.0×10~(-6)mol/L的范围内呈线性关系,检出限为2.0×10~(-8)mol/L。实验表明,该极谱峰属于络合物吸附波,测定其络合比为Bi(Ⅲ):N-BPHA=1:3。测定了该体系的吸附量;Bi(Ⅲ)-N-BPHA络合物在悬汞电极上的吸附符合Frumkin等温式,测得吸附系数β=2.87×10~5,吸引因子α=0.984。用于矿石中微量铋的测定。     

二次微分简易示波伏安法测定痕量镍

用二次微分简易示波伏安法测定了金刚石酸洗废液中的痕量镍 .结果表明 :在 0 .2 0mol/ L NH4 Ac- 0 .0 0 5mol/ L KNO3- 0 .0 2 %丁二酮肟中 ,Ni2 浓度在 3× 10 -7～ 3.5× 10 -6mol/ L范围内与峰高呈线性关系 ,回归方程为 Y=0 .3583 1.365× 10 5c( Ni2 ) ( mol/ L) ,相关系数 r=0 .9970 ,检测下限为 6× 10 -8mol/ L.该法简单、快速、灵敏     

配位吸附波同时测定PbⅡ和In(Ⅱ)

在0.05 mol/L氯乙酸-氯乙酸钠(pH 3.0)介质中,Pb2+、In3+与二溴邻苯二胺双草酰胺酸酯(DBAC)生成络合物,并吸附于电极表面,分别于-0.50V、-0.63V(vs.SCE)得到络合物吸附还原波.其二阶导数峰电流与Pb2+、In3+浓度分别在2.5×10-8～6.0×10-6 mol/L 、7.5×10-8～3.4×10-6 mol/L内呈良好的线性关系;检出限分别为1.5×10-8 mol/L Pb2+和4.5×10-8 mol/L In3+.应用于陶瓷颜料、矿石中微量Pb、In的测定,结果满意.     

碳糊电极吸附伏安法测定痕量钒

研究了钒 荧光镓(LMG)络合物在碳糊电极上的吸附伏安行为,发现其在+0.81V(vs.SCE)的阳极二次导数峰电流与钒(V)的浓度在一定范围内呈线性关系。在pH=4.3的0.26mol/L的HAc NH4Ac缓冲溶液中,于+0.4V富集,从+0.4至+1.4V以300mV/s线性扫描,方法线性范围为4.0×10-9～1.0×10-7mol/L(5.0×10-7mol/LLMG)和1.0×10-7～1.2×10-6mol/L(2.0×10-6mol/LLMG),检出限为1.0×10-9mol/L(S/N=3)。该法用于煤飞灰,粉煤灰和水样中钒的测定,结果满意。     

锆(Ⅳ)-邻苯二酚紫络合物碳糊电极阳极吸附伏安法研究

研究了锆(Ⅳ)-邻苯二酚紫(PV)络合物在碳糊电极上的吸附伏安行为。测定锆最佳条件为:0.08mol/L的HNO3为底液,于0.4V富集50s,从0.4至1.4V以100mV/s的速率线性扫描。在0.85V(vs.SCE)的二次导数氧化峰电流与锆的浓度在3.0×10-9～5.0×10-8mol/L(5.6×10-7mol/LPV)和1.0×10-8～1.0×10-7mol/L(5.6×10-6mol/LPV)成线性关系。富集80s,检出限为1.0×10-9mol/L(S/N=3)。该法用于标准岩石样品中锆的测定,不需萃取分离和掩蔽,直接测定,结果满意。铪(Ⅳ)在同样的实验条件下也于0.85V产生一络合吸附峰,灵敏度稍低于锆。     

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.