L-半胱氨酸自组装膜电极对米吐尔的电催化及其分析应用

研究了米吐尔在L 半胱氨酸自组装膜修饰金电极上的电化学行为。米吐尔在该修饰电极上的CV曲线仅出现一对峰 ,其峰形对称 ,ΔEp =42mV ,氧化还原峰电流之比约等于 1,为可逆反应 ;扩散系数D =2 .2 4× 10 - 6 cm2 ·s- 1 。初步探讨了电催化机理。差分脉冲伏安法测定其氧化峰电流与米吐尔浓度在 5 .0× 10 - 7～ 2 .0× 10 - 5mol/L和 5 .0× 10 - 5～ 1.0× 10 - 3 mol/L范围内分段呈线性关系 ;相关系数分别为 0 .9987和 0 .9972 ;检测限 1.0× 10 - 8mol/L     

酪氨酸、脯氨酸和组氨酸的示波极谱连续测定

提出了用示波极谱法连续测定酪氨酸 ( Tyr)、脯氨酸 ( Pro)、组氨酸( His) 3种氨基酸的新方法。在 p H9.2硼酸缓冲溶液中 ,上述 3种氨基酸与镍发生配位反应 ,用示波极谱仪进行单扫描时 ,出现 3组灵敏度和分辨率均很高的二阶导数波谱 ,峰电位分别为 :Tyr - 1 .0 4 V,Pro - 1 .2 0 V,His - 1 .34V。酪氨酸、脯氨酸、组氨酸的峰电流与浓度分别在 2 .0× 1 0 -5～ 3.0× 1 0 -4 mol/L,3.2× 1 0 -6～ 2 .2× 1 0 -4 mol/L,4.0× 1 0 -5～ 2 .5× 1 0 -4 mol/L的范围内呈线性关系。该法已用于复方氨基酸注射液中酪氨酸、脯氨酸、组氨酸含量的测定。     

噻吩甲酰三氟丙酮的电化学性质及应用

在 0 .5mol/LHCl和 0 .2g/L的明胶溶液中 ,利用线性扫描极谱法测定噻吩甲酰三氟丙酮 (简称TTA) ,发现有一还原峰 ,其峰电位是 - 1 .0 0V (vs.SCE)。峰电流与TTA浓度在 2 .5× 1 0 - 5mol/L～ 2 .0× 1 0 - 3mol/L之间存在线性关系 (r=0 .9986) ,检测下限为 1 .0× 1 0 - 5mol/L。利用单扫描极谱法和循环伏安法对极谱峰的电化学性质进行了研究     

磷酸可待因在Nafion修饰玻碳电极上的伏安行为研究及测定

用循环伏安法和微分脉冲吸附伏安法对磷酸可待因在Nafion修饰玻碳电极上的伏安行为进行了研究。结果表明在 0 .1mol/LHCl底液中 ,磷酸可待因在 + 1 .0 6V处 (vs.SCE)产生一良好的氧化峰 ,磷酸可待因浓度在 5 .0× 1 0 - 7～2 .5× 1 0 - 5mol/L范围内与峰电流呈线性关系 ,检出限为 1 .3× 1 0 - 7mol/L。并分别对其单方药和复方药制剂进行了测定     

茜素紫修饰碳糊电极阳极溶出伏安法测定痕量锡

研究了利用茜素紫修饰碳糊电极测定痕量锡的阳极溶出伏安法。在 0 1 5mol/L醋酸盐缓冲溶液 (pH 4 .8)中 ,通过开路富集 ,Sn 和茜素紫形成络合物富集于电极表面 ,然后经过介质交换至 3 0mol/L的盐酸溶液中 ,于 -0 .80V还原后再进行阳极化扫描 ,于 -0 .68V左右获得一灵敏的锡的溶出峰。二次导数峰电流与Sn 浓度在 8.4× 1 0 -9～ 1 .4× 1 0 -6mol/L范围内呈良好的线性关系。检出限达 4×1 0 -9mol/L ,同时对电极反应机理进行了讨论。     

聚吖啶橙修饰电极伏安法测定黄嘌呤

报道了聚吖啶橙 (POAO)修饰电极多阶半微分伏安法测定黄嘌呤 (Xa)。在pH 5 .3的磷酸盐缓冲溶液中 ,Xa在POAO电极上于 0 .8V处产生一灵敏的氧化峰 ,峰电流与其浓度在 7.8× 1 0 - 8～ 1 .1× 1 0 - 6mol/L和 1 .1× 1 0 - 6～ 1 .0×1 0 - 5mol/L范围内呈良好的线性关系 ,检出限为 7.8× 1 0 - 9mol/L。方法可用于人尿中Xa的测定     

四种阴离子的毛细管电泳电导检测(英文)

 采用柠檬酸 柠檬酸钠作为缓冲体系 ,使用负高压 ,对Cl-,NO3 -,HCO3 -和H2 PO4 -等 4种常见阴离子进行了分离检测 ,研究了缓冲剂的种类、浓度、pH值及操作电压对分离的影响。在选定的条件下 ,4种离子的定量线性范围 :Cl-5 0× 10 -5mol/L～ 2 5× 10 -3 mol/L ,NO3 -6 0× 10 -5mol/L～ 2 0× 10 -3 mol/L ,HCO3 -5 0× 10 -6mol/L～ 2 0× 10 -4 mol/L ,H2 PO4 -6 0× 10 -5mol/L～ 1 0× 10 -3 mol/L ;检出限 :Cl-1 5× 10 -5mol/L ,NO3 -3 0×10 -5mol/L ,HCO3 -1 0× 10 -6mol/L ,H2 PO4 -2 0× 10 -5mol/L ;峰面积的RSD (n =6 ) :Cl-3 1% ,     

二次微分简易示波伏安法用于葛根素测定

根据在 0 .1 mol/ L Na OH溶液中 ,葛根素在二次微分简易示波伏安图阴极支-0 .95V ( vs.SCE)产生一灵敏峰的示波特性 ,建立了二次微分简易示波伏安法测定药品中葛根素含量的新方法。线性范围为 2 .5× 1 0 - 6～ 3 .5× 1 0 - 5mol/ L,相关系数为 0 .9985,检出限为 1× 1 0 - 6mol/ L,对 9.0× 1 0 - 6mol/ L葛根素进行 5次测定的RSD为 1 .5%。利用该法测定中药葛根及心可舒片剂中葛根素的回收率分别为 1 0 0 .2 %和 96.9%。     

奥美拉唑的示波极谱法测定及其电化学行为

在 0 .1 mol/L NH3- NH4 Cl( p H 8.90 )底液中 ,奥美拉唑在汞电极上有一灵敏的导数还原峰 ,峰电位 Ep=- 1 .1 0 5 V ( vs.SCE) ,峰高与奥美拉唑的浓度在 5 .0×1 0 - 7～ 1 .0× 1 0 - 5范围内呈线性关系 ( r=0 .9989) ,检出限为 2 .0× 1 0 - 7mol/L。该法应用于胶囊中奥美拉唑含量的测定 ,结果满意。对奥美拉唑在汞电极上的电化学行为进行了探讨     

槲皮素修饰碳糊电极吸附溶出伏安法测定人血清中铜

制作了用槲皮素作修饰剂的修饰碳糊电极 ,利用此电极为工作电极 ,建立了测定痕量铜的新方法。在甲酸钠 -盐酸缓冲溶液 ( p H4.7)中 ,于 0 .2 0 V( vs.SCE下同 )处搅拌富集 ,铜 ( )与碳糊修饰电极表面的槲皮素形成电活性络合物而吸附富集于电极表面 ,于 - 0 .40 V静止还原后 ,阳极化线性扫描 ,在 - 0 .0 3V左右获得一灵敏的二次导数溶出峰。在不同富集时间下 ,其二次导数峰电流与铜 ( )浓度分别在1 .5× 1 0 - 9～ 8.0× 1 0 - 8mol/ L和 1 .5× 1 0 - 8～ 9.0× 1 0 - 7mol/ L两个范围内成良好的线性关系 ,检出限可达 8.0× 1 0 - 10 mol/ L。同时探讨了电极反应机理。方法应用于人血清中痕量铜的测定 ,获得了令人满意的结果     

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.