靛玉红在碳糊电极上的阴极吸附伏安法研究

在0.10 mol/L的K2HPO4-NaH2PO4（pH8.5）缓冲液中,使用JP-303极谱分析仪,靛玉红在碳糊电极（CPE）上有一灵敏的吸附伏安还原峰,峰电位为-0.60 V（vs.SCE）。该还原峰的二阶导数峰电流与靛玉红的浓度在8.0×10^-9-8.0×10^-7mol/L（富集90 s）范围内呈良好的线性关系,相关系数为0.9976,检出限为4.0×10^-9mol/L（S/N=3,富集110 s）。探讨了靛玉红在碳糊电极上的伏安性质和电极反应机理,并应用于中草药大青叶中靛玉红含量的测定。     

依诺沙星在碳糊电极上的阳极吸附伏安法研究

在0.40 mol/L的NaAc-HAc(pH 4.5)缓冲液中,使用JP-303极谱分析仪,依诺沙星在碳糊电极(CPE)上有一灵敏的吸附伏安氧化峰,峰电位为1.17 V(vs.SCE).该氧化峰的二阶导数峰电流与依诺沙星的浓度在4.0×10-9～4.0×10-7 mol/L(富集90 s)范围内呈良好的线性关系,相关系数为0.995,检出限为2.0×10-9 mol/L(S/N=3,富集110 s).探讨了依诺沙星在碳糊电极上的伏安性质和电极反应机理,并且用于诺佳胶囊中依诺沙星的测定.     

碳糊电极阴极吸附伏安法测定橙皮甙

在0.4mol/L的NH4Cl-NH3(pH9.0)缓冲液中,使用JP-303极谱分析仪,橙皮甙在碳糊电极(CPE)上有一灵敏的吸附伏安还原峰,峰电位为-1.2V(vs.SCE).该还原峰的二阶导数峰电流与橙皮甙的浓度在2.0×10-8～1.0×10-6mol/L(富集90s)范围内成良好的线性关系,相关系数为0.9963,检出限为1.0×10-8mol/L(S/N=3,富集110s).探讨了橙皮甙在碳糊电极上的伏安性质和电极反应机理,并且成功应用于中草药桔皮中橙皮甙含量的测定.     

碳糊电极阳极吸附伏安法测定洛美沙星

报道了碳糊电极阳极吸附伏安法测定洛美沙星的新方法。在0.096mol L的KHP NaOH(pH5.4)缓冲液中,用碳糊电极为工作电极,在0.3V(vs.SCE)富集一定时间,然后从0.3～1 3V以300mV s扫速线性扫描,记录其在1 02V的二次导数阳极溶出峰。溶出峰电流与洛美沙星浓度在8.0×10-9～8.0×10-8mol L(富集90s)和8.0×10-8～8.0×10-7mol L(富集30s)范围内呈良好的线性关系,相关系数分别为0.9844和0.9967,检出限为9.0×10-10mol L(S N=3)。探讨了洛美沙星在碳糊电极上的伏安性质和电极反应机理,并且成功地应用于人体尿液中洛美沙星的测定,结果与紫外光度法基本吻合。     

碳糊电极阳极吸附伏安法测定卡托普利

在0.40 mol/L的HAc-NaAc(pH=4.8)缓冲溶液中,卡托普利(Captopril,CPT)在碳糊电极(CPE)上有一灵敏的吸附氧化峰,峰电位为0.23 V(vs.SCE)。该氧化峰的二阶导数峰电流与卡托普利的浓度在2.0×10-8～1.0×10-6mol/L(富集90 s)范围内呈良好的线性关系,相关系数为0.9966,检出限为8.0×10-9mol/L,并成功应用于卡托普利片含量的测定。探讨了卡托普利在碳糊电极上的伏安性质和电极反应机理。     

离子液体BMIMPF6修饰碳糊电极电化学测定维生素E

用疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸([BMIM]PF6)作粘合剂制备了离子液体修饰碳糊电极(IL/CPE)。采用循环伏安法(CV)研究了维生素E(vitamin E,VE)的氧化产物生育酚红在IL/CPE和未修饰碳糊电极(CPE)上的电化学行为,结果表明生育酚红在IL/CPE上氧化过程更易于进行,峰电流响应ip也明显增加,表明IL/CPE对生育酚红的氧化还原反应具有良好的电催化作用。同时测定了电极过程的动力学参数:电荷转移系数α=0.8746,扩散系数D=1.65×10-3cm2/s,电极反应速率常数kf=6.64×10-2cm/s。采用方波伏安法(SWV)发现生育酚红氧化峰电流与其浓度在1.53×10-4mol/L～8.39×10-7mol/L范围内呈线性关系,检出限为1.58×10-8mol/L。该法可用于VE实际样品的分析测定。     

纳米二氧化铈修饰碳糊电极线性扫描伏安法测定苯酚

在0.01mol.L-1硼砂溶液(pH 9.18)中,用纳米二氧化铈修饰碳糊电极作为工作电极,线性扫描伏安法测定苯酚。伏安图上出现一灵敏的氧化峰,其峰电位为+0.56V(vs.SCE),峰电流与苯酚的浓度在1.0×10-7～2.0×10-4 mol.L-1范围内呈线性关系,检出限(3s/k)为5.0×10-8 mol.L-1。富集时间为30s,同时采用线性扫描伏安法研究苯酚在纳米二氧化铈修饰碳糊电极上的氧化还原反应,结果表明此电极反应为一不可逆的吸附过程。     

碳糊电极阳极吸附伏安法测定诺氟沙星

报道了用碳糊电极阳极吸附伏安法测定诺氟沙星的方法。在0.40 mol.L-1的NH4OAc-HOAc(pH 4.51)缓冲溶液中,诺氟沙星在碳糊电极(CPE)上有一灵敏的吸附氧化峰,峰电位为1.16 V(vs.SCE)。该氧化峰的二阶导数峰电流与诺氟沙星的浓度在4.0×10-9~4.0×10-7mol.L-1(富集90 s)范围内呈线性关系,相关系数为0.996,检出限为1.0×10-9mol.L-1(S/N=3,富集110 s);应用于人体尿液中诺氟沙星含量的测定,方法的回收率为99.1%~104.0%。文中探讨了诺氟沙星在碳糊电极上的伏安性质和电极反应机理。     

碳糊电极吸附溶出伏安法测定游离钙

基于Ca(Ⅱ)-茜素红S(ARS)络合物在碳糊电极上的还原波,建立了吸附溶出伏安测定游离钙的新方法。在1.5×10-2mol/LKOH-2.0×10-5mol/LARS介质中,Ca(Ⅱ)-ARS络合物在碳糊电极上于-0.89V处产生一吸附还原波。当富集电位为.0.1V,富集时间90s,扫描速度为100mV/s时,该络合物单扫描阴极溶出峰的二阶导数峰电流与游离钙离子浓度在3.0×10-8~2.0×10-6mol/L范围内呈线性关系;检出限为9.4×10-9mol/L。在0.2mol/LHCl中清洗2min,该电极重现性良好。该方法可用于血清、牛奶和自来水中游离钙的测定。     

茜素红S/多壁碳纳米管修饰碳糊电极阳极溶出伏安法测定痕量铜

制备了茜素红S/多壁碳纳米管修饰碳糊电极,提出了一种灵敏的溶出伏安法测定痕量铜的新方法.在极谱分析仪上采用二阶导数线性扫描伏安法进行分析,在0.1 moL/L的HAc-NaAc缓冲溶液(pH 4.1)中,Cu与修饰电极表面的茜素红S(ARS)形成Cu(Ⅱ)-ARS络合物而富集于电极表面,于-400 mV处还原后,再进行阳极化扫描,于64 mV处获得一灵敏的铜的阳极溶出峰,峰电流与Cu(Ⅱ)浓度在2×10-11 mol/L～6×10-7 mol/L范围内呈良好的线性关系,检出限(S/N=3) 为8.0×10-12 mol/L(富集时间240 s).方法应用于人发中铜含量的测定,回收率为98%～102%.     

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%.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.