外反射式微薄层现场显微红外光谱电化学池设计

本报道一种能很好适用于固态分析了现场研究的外反射式微盘电极薄层显微红外光谱电化学池设计。该池使用１００μｍ直径微铂盘工作电极，银盘参比电极和同心环形辅助电极。在ＰＥＧ４００／ＬｉＣＬＯ４体系中，池参数为：薄层厚０．６μｍ，表观薄层电阻１４ｍΩ，充电电容４×１０＾３ｐＦ，时间常数６０ｍｓ，并测得常温下Ｆｅ（ＣＮ）６＾３－／４－的表观扩散系数４×１０＾－７ｃｍ＾２／ｓ，获了良好分辨Ｆｅ（ＣＮ）６＾３     

冰醋酸中肾上腺素的现场光谱电化学行为

采用以石墨为工作电极的长光程薄层光谱电化学池, 用循环伏安法、恒电位光谱法和单电位跃计时吸光度法,研究了肾上腺素(AD)在冰醋酸介质中的电子转移反应。结果表明:AD在冰醋酸介质中电氧化反应产物为肾上腺素醌,还原态和氧化态的扩散系数分别为 3. 98×10-6 cm2 /s和 3. 90×10-6 cm2 /s;电极反应的式量电极电位为 0. 632V(vs.SCE),式量异相电子转移速率常数为 7. 30×10-4cm/s;传递系数为 0. 15。     

长光程薄层紫外-可见光谱电化学法测定多巴胺

利用一种长光程薄层光谱电化学池,建立了在抗坏血酸存在下测定多巴胺的紫外-可见光谱电化学法。测定条件为：在pH=6．0的PBS介质中,电极电位在0．6V（vs.Ag/AgCl）,测定波长为300nm多巴胺电氧化产物的吸光度,吸光度与多巴胺浓度在4×10－6～2．4×10－4mol/L范围内呈线性关系,检测限为1．0×10－6mol/L。用于多巴胺针剂的测定,结果令人满意。     

平行入射式光谱电化学池的制作及分析应用

本工作制作了用于定量分析的平行入射式光谱电化学池,电极长度为2 cm,光束高度约为120μm。稳定的吸光度在较宽的浓度范围内具有良好的线性关系,最低检测限对氢醌为3×10~(-8)mol/L,而对邻甲联苯胺为2×10~(-8)mol/L。利用光谱电化学可以在四倍的多巴胺存在下测定抗坏血酸,而大量存在的抗坏血酸对多巴胺的测定无影响。     

多用途薄层光谱电化学池的设计和表征

设计并组装了一种简易薄层光谱电化学池.该池具有结构简单、操作方便、对工作电极无透光要求,且能适用于多种现场光谱电化学研究的特点.用该池记录了邻联甲苯胺高氯酸醋酸组成的氧化还原体系的荧光光谱电化学和紫外可见光谱电化学响应,并用吡啶氯化钾体系进行了喇曼光谱电化学表征.     

反射式薄层可见光谱电解池的制作与性能测试

设计制作了一种反射式薄层可见光谱电解池。该电解池采用光亮铂片作为工作电极,将铂丝辅助电极和Ag AgCl参比电极组装在一起。薄层池中间的溶液薄层是通过光亮铂片和覆盖其上的玻璃片之间的塑料薄膜垫圈加以控制,当液层厚度为0.2mm时,液层容积为16μL。由于采用双平行反射的光路,使入射光与出射光保持在一直线上,可以在不变更光路系统下的各种光度计上使用。在K3Fe(CN)6 K4Fe(CN)6体系中,用循环伏安法、恒电位现场光度法进行性能测试。实验结果表明,该电池具有良好的薄层光谱电化学性能,可用于薄层可见光谱电化学研究。     

四硝基酞菁锌配合物的光谱电化学性质

带有各种取代基的酞菁配合物虽已有研究,但有关硝基酞菁锌配合物在溶液中的氧化还原产物研究尚未见报道.本文用薄层光谱电化学技术对该配合物的电解产物进行了研究. 1 实验部分 HDP-1型恒电位仪;F-78型脉冲极谱仪;UV-240型紫外可见分光光度计.四硝基酞菁锌(ZnTNPc)按文献合成和提纯.电化学实验在氮气中于三电极电解池中进行,工作电极(0.001cm~2)、辅助电极均为铂丝,银丝为参比电极,二茂铁作内参比物.支持电解质为0.1mol/L TBAP,ZnTNPc浓度为1.0×10~(-5)mol/L.光谱电化学实验方法见文献,电解液为0.3mol/L TBAP和1.0×10~(-4)mol/L ZnTNPc.     

双波长薄层紫外可见光谱电化学测定多巴胺

多巴胺 (DA)和抗坏血酸 (AA)的吸收光谱在 2 0 0～ 30 0nm内重叠严重 ,但在电化学氧化状态下 ,DA的氧化产物在 2 10 ,30 0和 4 80nm有强吸收峰 ,AA的氧化产物在 2 0 0～ 4 0 0nm范围内吸收较弱且呈光滑平缓的斜坡。在此基础上 ,利用自行设计的长光程薄层光谱电化学池建立了一种双波长光谱电化学法测定DA。测定条件为 pH 6 .2的磷酸盐缓冲液 (PBS) ,0 .6V (vs.Ag/AgCl)电极电位 ,双波长 318/ 2 93nm ,线性范围为 4 .0× 10 - 6 ～ 2 .0× 10 - 4mol·L- 1,检出限为 2 .0×10 - 6 mol·L- 1。对 6 .2 0× 10 - 5mol·L- 1DA进行 11次平行测定 ,平均相对偏差为 2 .6 %。与文献报道的吸光光度法相比 ,该法具有较高的灵敏度和选择性 ,较为有效地消除了AA的干扰 ,回收率在 91.8%～ 10 0 .8%之间 ,结果满意     

生物小分子次黄嘌呤在银电极上的电化学性质

本文研究了银电极上次黄嘌呤的电化学特性。在含次黄嘌呤的醋酸～醋酸钠缓冲溶液中(pH3.7)，在0.35～0V电位区间内，银电极上出现一个还原峰，扫速50 mV/s时，其峰电位约在0.15V。该电极过程为单电子单质子过程。电化学和光谱电化学结果表明：这是由于次黄嘌呤与银形成难溶性化合物吸附于银电极表面而造成的。实验测得此难溶化合物的组成为1∶1，其溶度积为3.10×10^-7。用DPSV作阴极溶出分析，峰电流与次黄嘌呤浓度在8.0×10^-7～1.0×10^-     

核黄素的薄层荧光光谱电化学研究

光谱检测技术和电化学手段密切结合起来的光谱电化学方法,加上薄层池的整体快速电解,已成为化学工作者的重要研究手段［１］．目前紫外可见透射光谱检测方法多采用铂、金、石墨等的网栅为工作电极,对其透光度及强度均有一定要求,操作不便,池也不易清洗［２］;并且由...     

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.