乙基橙指示催化动力学极谱法测定痕量铜

１　引　言在ＨＡｃ－ＮａＡｃ介质中，邻菲■啉（ｐｈｅｎ）存在下，痕量铜对抗坏血酸还原乙基橙反应具有强烈的催化作用，且在此条件下乙基橙于－０．３０Ｖ（νｓ　ＳＣＥ）处，有一灵敏的极谱波，以此作为监测反应过程中乙基橙的浓度变化，建立了测定铜的催化动力学极谱方法。２　实验部分２．１　仪器与试剂　ＪＰ３－１型示波极谱仪（山东电讯七厂），ＣＳ５０１型超级恒温器（重庆试验设备厂）。０．５０ｍｇ／ＬＣＵ（Ⅱ）标准溶液；７．０ｘ１０－４ｍｏｌ／Ｌ乙基橙溶液；０．５ｍｏｌ／Ｌ　ＨＡｃ－ＮａＡＣ缓冲溶液（ｐＨ＝４．…     

甲基红在痕量钼的催化反应—示波极谱分析中的新应用

实验发现，在硫酸介质及加热下，痕量钼（Ⅵ）对硫酸联氨还原甲基红这一缓慢褪色反应具有强烈催化作用；甲基红在氢氮化钠介质中于－０．７０Ｖ．ＳＣＥ处产生一灵敏的示波极谱波。据此，本文采用固定时间法，用示波极谱法研究了利用这一新的指示反应催化测定钼的影响因素，建立了一个检出限和测定范围分别为０．８ｎｇ／ｍＬ和１．６～１００ｎｇ／ｍＬ钼的催化反应－示波极谱法，并用于测定矿石和钢样中的钼。     

芦荟大黄素的电化学研究

用单扫示波极谱法研究了芦荟大黄素的电化学行为。在５％Ｎａ２ＣＯ３＋５％ＮａＯＨ（９＋１）底液中，芦荟大黄素于－０．８４Ｖ（Ｐ１）和－０．９７Ｖ（Ｐ２）处产生两个示波极谱峰，利用Ｐ１可测定芦荟大黄素，线性范围为 ０．１１－２４ｍｇ／Ｌ和３．０－２８．６ｍｇ／Ｌ，检测限为０．０６ｍｇ／Ｌ。将该法应用于中药大黄中的芦荟大黄素的测定，结果满意。另外，讨论了芦荟大黄素清除由邻苯三酚自氧化产生的超氧自由基（Ｏ２）的作用。     

马兜铃酸极谱研究

用单扫示波极谱法研究马兜的电化学行为。在０．１ｍｏｌ／ＬＮａＯＨ底液中，马兜铃酸在－０．８９Ｖ产生一良好的二阶导数 极谱峰，线性范围为０．０３－３２ｍｇ／Ｌ检出限为０．０１ｍｇ／Ｌ。     

单扫描极谱法测定水中痕量苯酚

苯酚与对硝基苯胺的重氮盐偶合后,在０．０３ｍｏｌ／Ｌ Ｎａ２ＣＯ３－０．０３ｍｏｌ／Ｌ ＮａＨＣＯ３－１６０ｇ／Ｌ乙醇介质中,偶合产物在单扫描示波极谱上产生一个灵敏而精晰的吸附还源波,波高与苯酚浓度在０．００５～０．５ｍｇ／Ｌ范围内呈良好线性关系,峰电位为－．０５８Ｖ（υｓ,ＳＣＥ）,方法检出限达０．００２ｍｇ／Ｌ。已用于天然水中痕量苯酚的测定。     

测定超氧化物歧化酶活性的一种新的极谱分析方法

报道一种测定超氧化物歧化酶活生的新极谱分析方法，在０．１２５ｍｏｌ／ＬＮＨ３．Ｈ２Ｏ－０．７５ＭＯＬ／ｌ ｎｈ４ｃＬ－２．５％，Ｎａ２ＳＯ３－０．５％，吐温－８０－的介质中，ＳＯＤ在－０．５２Ｖ处产生一氧极谱催化波。ＳＯＤ在１．０×１０＾３Ｕ／Ｌ－４．０×１０＾３Ｕ／Ｌ的活性含量范围内与催化电流呈线性关系，检出限为８．０×１０＾２Ｕ／Ｌ。     

柚皮革甙的电化学研究

用单扫示波极谱法，柚皮甙在０．１ｍｏｌ／ＬＫＨ２ＰＯ４中（ＰＨ＝４．６０）有一灵敏的二阶 导数峰，峰电位为－１．４３Ｃ，峰电流与浓度在０．１－２．８ｍｇ／Ｌ和３．０－４２ｍｇ／Ｌ范围良好线性关系，     

银(Ⅰ)-苯羟乙酸光反应的共振散射光谱研究

在０．０４ｍｏｌ／Ｌ Ｈ２ＳＯ４－０．０１ｍｏｌ／Ｌ苯羟乙酸介质中,Ａｇ＾＋被紫外光还原生成银胶,苯羟乙酸被光氧化生成苯甲醛。银胶于５２５ｎｍ处产生一灵敏的共振散射峰,银浓度在０．１～４．０μｇ／ｍＬ范围内与共振散射光强度呈良好线性关系。方法的检出限为０．０５μｇ／ｍＬ。该法已用于废水中银的测定。并采用共振散射光谱、紫外可见吸收光谱及示波极谱等探讨了光化学反应机理和共振散射现象。     

钙—芦丁极谱络合吸附波的研究

在０．０１ｍｏｌ／ＬＫＯＨ底液中，用单扫示波极谱法可获得钙－芦丁络合吸附波，检出限为８．０＊１０＾－７ｍｏｌ／Ｌ．电极表面反应速率常数为ｋｓ＝ｄ１．２７ｓ＾－１。     

安非拉酮示波极谱法研究

在０．ｌｍｏ１／ＬＨ＿２ＳＯ＿４溶液中，安非拉酮出现一灵敏的示波极谱导数还原波，Ｅ＿ｐ＝－０．８０Ｖ（ｖｓ．ＳＣＥ），峰高与安非拉酮的浓度在１．０×ｌ０￣－７～６．０×１Ｏ６ｍｏｌ／Ｌ范围内成线性关系，检出限为１．０×１０￣－７ｍｏｌ／Ｌ用于片剂测定，得到满意的结果。用循环伏安法等手段研究体系的极谱和伏安行为，测得吸附量，吸附系数β＝５．６×１０￣－４，吸引因素ａ＝０．４９，吸附自由能△Ｇ＝－２７ｋＪ／ｍｏｌ。实验表明，该体系属不可逆吸附波。     

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%.     

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.     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.