克拉霉素与苯基荧光酮的荷移反应及其测定

本文建立了一种测定克拉霉素的荷移分光光度法,克拉霉素与苯基荧光酮(PF)在乙醇溶液中发生荷移反应,荷移络合物在波长519nm处有最大吸收,其表观摩尔吸光系数为1.70×104 L·mol-1·cm-1,荷移络合物的组成比为1∶1,稳定常数为2.86×104,药物浓度在5.0×10-6~7.0×10-5 mol/L范围内服从比耳定律,当克拉霉素浓度为4.0×10-5 mol/L时,8次测定结果的相对标准偏差(RSD)为0.46%,检出限为6.0×10-7 mol/L。利用该法测定了克拉霉素胶囊中有效成分的含量,回收率大于98%以上。     

β-环糊精增敏荧光法测定克拉霉素含量的研究

克拉霉素在λex=275、λem=325处能产生荧光,经β-环糊精增敏后,荧光强度大大增强,据此建立了测定克拉霉素含量的新方法。克拉霉素的浓度在5.0×10-7～5.0×10-6 mol/L范围内与体系荧光强度呈良好的线性关系,相关系数R=0.9992,检出限为3.9×10-7 mol/L。对药物制剂中克拉霉素的含量进行测定,测定值与标示值吻合,回收率在97%以上。该方法可用于测定胶囊和血清样品中克拉霉素的含量。     

微分脉冲阴极溶出伏安法测定呋喃唑酮

研究了呋喃唑酮在玻碳电极上的伏安行为。在 1mol LHCl底液中 ,用微分脉冲阴极溶出伏安法得到一灵敏的呋喃唑酮还原峰 ,峰电位为 0 .0 38V(vs.Ag AgCl)。峰电流与呋喃唑酮浓度在 8× 1 0 -6～ 1× 1 0 -4 mol L范围内呈线性关系 (r=0 .9984) ,检出限为 8× 1 0 -8mol L。该法已用于片剂与合成血清样品中呋喃唑酮含量的测定     

催化氢波-单扫描示波极谱法测定克拉霉素

建立一种灵敏快速测定克拉霉素的新方法。在 0. 24 mol·L-1 KH2PO4 Na2HPO4(pH 6.81)支持电解质中,克拉霉素于-1.57 V(vs.SCE)处产生一催化氢波,其二阶导数峰峰电流与克拉霉素浓度在2.0×10-6~ 1.6×10-4mol·L-1范围内呈线性关系(r=0.999 4,n=8),检出限为1.0×10-6 mol·L-1。10 次测定 1. 0×10-5 mol·L-1 克拉霉素峰电流相对标准偏差为1 8%,回收率在98.3%~100.6%之间。该方法可用于药剂中克拉霉素的测定。     

4-甲氧基-2,6-二(3,5-二甲基吡唑)-1,3,5-三嗪碳糊修饰电极测定Co(Ⅱ)的研究

用 4 甲氧基 2 ,6 二 (3,5 二甲基吡唑 ) 1 ,3,5 三嗪作碳糊修饰剂 ,采用示差脉冲阳离子溶出伏安法对痕量钴的测定进行了研究。测试介质为 1 .0mol LNH4Cl(pH 5 .50 )溶液 ,参比电极为Ag AgCl。向正电位方向扫描时 ,Co(Ⅱ )的氧化峰在 - 0 .0 7V ,Co(Ⅱ )的浓度在 1 .0×1 0 -7～ 1 .0× 1 0 -8mol L,2 .0× 1 0 -7～ 6 .0× 1 0 -6mol L两个范围内与峰电流成线性关系 ,且大多数阳离子不干扰测试结果。用于饮用水中Co(Ⅱ )的测定 ,结果与文献一致     

对硫磷在纳米氧化铝薄膜修饰电极上的电化学行为及其测定

制备了纳米氧化铝修饰玻碳电极(nano-Al2O3/GCE/CME),用循环伏安法(CV)、线性扫描伏安法(LSV)研究了对硫磷(TP)在nano-Al2O3/GCE/CME上的电化学行为.实验表明,该修饰电极与裸电极相比能显著提高TP的氧化还原峰电流并降低其氧化峰电位.在0.1 mol/L HAc-NaAc缓冲溶液(pH =5)中,TP在该修饰电极上产生1个不可逆的还原峰( Epc1=-0.567 V)和1对可逆氧化还原峰( Epa2=0.018 V和Epc2=-0.008 V) ,氧化峰电流与TP的浓度在2.5×10-9～1.0×10-7 mol/L和1.0×10-7～1.0×10-5 mol/L范围内具有良好的线性关系,回归方程分别为: ip(μA)=0.2529+4.201C(μmol/L), r=0.9984和ip(μA)=0.6752+0.3181C(μmol/L), r=0.9946.开路富集30 s后,检出限为1.0 ×10-9 mol/L(S/N=3).在1.0×10-5 mol/L TP试液中连续测定10次,其RSD为3.8%.用此方法测定了蔬菜中TP的含量,回收率为95. 6%～100.5% ,结果满意.     

流动注射化学发光法测定甲硝唑

在碱性条件下 ,铁氰化钾氧化鲁米诺产生化学发光 ,甲硝唑对该体系有显著的增强作用 (亚铁氰化钾存在时 )。基于此 ,建立了流动注射化学发光测定痕量甲硝唑的新方法。甲硝唑浓度在 2 .0× 1 0 -6～ 4 .0× 1 0 -4 mol L范围内与发光强度呈良好的线性关系 ;检出限 (3σ)为 1 .5× 1 0 -7mol L。相对标准偏差 (c =1 .0× 1 0 -5mol L ,n=1 1 )为 3.6 %。方法已用于制剂中甲硝唑含量测定     

丙环唑-铜(Ⅰ)配合物的极谱法研究

在pH=8.00的0.4 mol/L NH3-NH4Cl缓冲溶液中,丙环唑与铜(Ⅰ)配位并在-0.88 V(vs.SCE)处产生新的还原峰,用线性扫描循环法测定此峰为不可逆,其峰电流与丙环唑浓度在6.00×10-6~8.00×10-5mol/L范围内呈现良好的线性关系,相关系数r=0.9989;检出限为4.00×10-6mol/L;测得电活性配合物丙环唑-铜(Ⅰ)中丙环唑与铜(Ⅰ)之比为2∶1,稳定常数为5.81×1012。     

极谱催化波法测定土霉素

H2 O2 存在时 ,产生土霉素的极谱催化波 ,该催化波的灵敏度比相应土霉素的还原波高 8倍 ,据此拟定了测定土霉素的新方法。在 0 .1 0mol LKH2 PO4 Na2 HPO4(pH 7.4± 0 .2 ) - 1 .6× 1 0 -3 mol LH2 O2 底液中 ,催化波峰电流与土霉素浓度在 5 .0× 1 0 -7～ 9.0× 1 0 -6mol L范围内呈线性关系 (n =1 0 ,r=0 9996)。检出限为 1 .0× 1 0 -7mol L。     

吡啶类碳离子液体电极对酚磺乙胺的电化学行为及其分析应用

用离子液体1-丁基吡啶六氟磷酸盐(BuPyPF6)作为粘合剂构置了碳离子液体修饰电极(BuPyPF6-CILE).在0.05 mol/L H2SO4溶液中,用循环伏安法研究了在BuPyPF6-CILE和传统碳糊电极(TCPE)上酚磺乙胺(ESL)的电化学行为,建立了测定尿样和血清样品中ESL含量的新方法.ESL在BuPyPF6-CILE上的氧化峰电流响应是其在TCPE上的8.7倍,峰电位差降低到0.101 V,电子转移速率常数Ks=0.544 s-1,电极表面平均吸附量为1.66×10-9 mol·cm2.ESL的氧化电流与其浓度在8.0×10-8～2.0×10-6mol/L和5.0×10-6～1.0×10-4mol/L范围内呈线性关系,检出限为3×10-8mol/L(S/N=3).连续5次测定2.0×10-6mol/L ESL溶液的RSD为1.5%.     

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.