胆红素的伏安特性及其微分脉冲伏安法测定

建立中成药中胆红素定量测定的微分脉冲伏安法。在多种介质中研究胆红素在玻碳电极上的电化学行为 ,全面优化条件后 ,采用标准加入法对中成药中胆红素进行测定 ,并通过与药典中标准方法对照和干扰实验及回收率实验对本方法进行评价。在 0 .2mol·L-1HAc NaAc 5 0 %EtOH和 1 1 5mol·L-1KH2 PO4 Na2 HPO4 溶液中 ,峰电流与胆红素浓度分别在 6.2 5× 1 0 -7～ 1 .0 0× 1 0 -5mol·L-1(r=0 .9976)和 5 .0 0× 1 0 -8～ 3.0 0× 1 0 -6mol·L-1(r=0 .9939)范围内呈良好的线性关系 ,检测下限分别为 5 .0× 1 0 -8mol·L-1和 5 .0× 1 0 -9mol·L-1。众生丸和牛黄解毒片中胆红素的质量分数分别为 0 .0 86%和 0 .1 0 9% ,RSD分别为 3 4%和 3.0 % ,回收率为 96.6%～ 1 0 4 .1 % ,其结果与药典中标准方法测定结果基本一致。     

四氯络汞(Ⅱ)离子电极的研制及其应用研究

以十六烷基双硫腙·四氯络汞 (Ⅱ )为载体 ,制备了PVC膜四氯络汞 (Ⅱ )阴离子选择性电极 ;测定了40多种金属离子以及阴离子的选择性 ,除Sn(Ⅳ)、Sb(Ⅲ )稍有干扰外 ,其它金属离子均无明显的干扰 ;25℃时 ,1mol·L-1 NaCl-1×10-3 mol·L-1HCl溶液中 ,汞(Ⅱ)浓度在6×10-6～1.0×10-2 mol·L-1 呈线性响应 ,斜率为31±2mV/decade,检出限为4×10 -6mol·L -1;用电位法测得汞在蔬菜中的回收率为92.5%～97.2 % ,相对标准偏差在0.8 %～1.6 %范围 ;该法用于绿萍、莴笋、丝瓜等中微量汞的含量测定 ,结果令人满意。     

微分电位溶出法连续测定饮料中的铜铅镉锌

建立了微分电位溶出法连续测定饮料中痕量铜、铅、镉、锌的新方法。在HAc- Na Ac( p H4 .5)～ 3.5× 1 0 -2 mol·L-1KCl～ 2 .6× 1 0 -5 mol· L-1Hg2 +介质中测定锌 ,然后调节底液为 0 .0 1 mol·L-1HCl,连续测定铜、铅、镉。铜、铅、镉、锌 ,检出限分别为 4 ,0 .1 ,2 ,4 μg· L-1,线性测定范围 Zn2 +:0～ 30 0 μg·L-1,Cu2 +、Pb2 +、Cd2 +:0～ 2 2 0μg· L-1,回收率为 83.4 %～ 1 0 3.3% ,RSD<3.4 % ( n=7)。该法较好解决了金属互化物的影响 ,样品不需消化便可直接测定。     

流动注射在线微柱预富集火焰原子吸收光谱法测定痕量铂

研究了流动注射在线微柱分离 预富集火焰原子吸收光谱法测定痕量铂的新体系。以α 氨基吡啶树脂作预富集试剂 ,以 2mol·L-1HCl + 0 .3mol·L-1NaClO4 混合液作洗脱剂。当进样体积为 15 .2ml,洗脱液体积为 0 .2 7ml时 ,浓集效率达 30倍 ,采样频率 2 8次·h-1。该方法检出限 (3σ)5 .2 μg·L-1,RSD为 1.4 % (n =11,1μg·ml-1铂 )     

在二甲亚砜中La—Fe合金膜电化学制备的研究

研究了二甲亚砜 (DMSO)中La3 和Fe2 在Pt ,Cu和Ni电极上的电化学行为。Fe2 在Pt电极上一步不可逆还原为Fe ,La3 在Pt电极上表现为准可逆电极过程。在 2 98K时 ,利用循环伏安法测定了 0 0 1mol·L- 1 FeCl2 0 1mol·L- 1 LiCl DMSO溶液中Fe2 的扩散系数、传递系数分别为 2 5 4× 10 - 6 cm2 ·s- 1 和 0 2 4;利用计时电流法测定了 0 0 1mol·L- 1 LaCl3 0 1mol·L- 1 LiCl DMSO溶液中La3 的扩散系数为 3 10×10 - 6 cm2 ·s- 1 。在铜电极上于 -1 75 0～ -2 45 0V (vs .SCE)下恒电位电解 ,可获得La含量达 2 2 7%～ 3 7 1%的La Fe合金膜 ;应用脉冲电解技术于 2～ 6mA·cm- 2 也可获得La Fe合金膜。这些合金膜是均匀的 ,粘附性好并有金属光泽     

单扫示波极谱法同时测定钴与镍

在 pH 9.70的Na2 CO3 NaHCO3、亚硝基红盐和氯代十四烷基吡啶体系中 ,镍和钴均有灵敏的络合物吸附波 ,其二阶导数峰电位分别为 - 0 .6 4V (vs .SCE) (镍 )和 - 0 .80V (vs .SCE)(钴 ) ,电流峰高与浓度在 3.4× 10 - 9～ 3.74× 10 - 6 mol·L- 1(镍 )和 7.0× 10 - 11～ 6 .0× 10 - 6 mol·L- 1(钴 )范围内呈线性关系 ,检出限分别为 2 .4× 10 - 9mol·L- 1(14 1ng·L- 1镍 )和 3.2× 10 - 11mol·L- 1(1.9ng·L- 1钴 )。方法应用于水样和生物样品中微量钴和镍的测定 ,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     

柱后衍生离子色谱法测定饮用水中IO3^- ClO2^- BrO3^-和NO2^-的研究

为建立柱后衍生离子色谱法同时测定饮用水中的IO-3、ClO-2、BrO-3和NO-2,采用高容量柱,以8.0 mmol·L-1碳酸钠作淋洗液,0.5 g·L-1邻二甲氧基联苯胺盐酸盐+5 g·L-1溴化钾+25%甲醇+1.0 mol·L-1硝酸作衍生剂,反应温度60℃,450 nm波长处检测.方法的线性范围广、相关性好(r>0.999),相对标准偏差为0.84%～5.4%(n=6),样品加标回收率91.3%～108.0%,检出限0.023～0.97μg·L-1.方法适用性好,可满足上述痕量阴离子试样的测定.     

硫代硫酸根的溶出伏安吸附性质及应用

在 0 .0 1mol·L-1LiNO3介质中 (pH 2 .70 )S2 O32 -有一灵敏的阴极溶出峰( - 0 .42V) ,其峰电流与S2 O32 -浓度在 1× 1 0 -7mol·L-1～ 4× 1 0 -6mol·L-1范围内有线性关系。当富集 2 0 0s时 ,检测限可达 5× 1 0 -8mol·L-1。溶出峰具有吸附性质 ,在悬汞电极上的吸附符合Frumkin等温式。测得在悬汞电极上的饱和吸附量为 1 .0 3× 1 0 -9mol·cm-2 。该方法用于PbS2 O3溶度积的测定 ,结果与文献值基本一致。     

琼脂固溶胶中的抗坏血酸在玻碳电极上的电化学行为

在玻碳电极上研究了 0.05 mol·L-1 Na2HPO4 0.05 mol·L-1 NaH2PO4 20.0 g·L-1琼脂固溶胶中抗坏血酸的电化学行为,并与 0. 05 mol·L-1 Na2HPO4 0. 05 mol·L-1NaH2PO4 溶液中的抗坏血酸在玻碳电极上的电化学行为进行了比较,对抗坏血酸的氧化产物用紫外光谱进行了鉴定。提出了一种用于研究电极反应机理及电化学合成有机化合物的新方法。     

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.