催化动力学光度法测定痕量碲的研究

本文研究了甲基红，次磷酸钠，钯（Ⅱ），碲（Ⅳ）之间的催化反应，建立了一种测定超痕量碲（Ⅳ）的新方法，方法检出限为１．２×１０＾－１１ｇ／ｍＬＴｅ（Ⅳ）测定范围为０．００１～０．１μｇ／２５ｍＬＴｅ（Ⅳ），用于测定生物样品中的痕量Ｔｅ（Ⅳ）获得了满意结果。     

人发和血清中痕量碲的示波极谱测定

碲（ＩＶ）在０．０３ｍｏｌ／Ｌ草酸－０．０００６％次甲基蓝介质中，在电位－０．６５Ｖ（ｖｓ．ＳＣＥ）处，有一尖锐灵敏的导数极谐波，峰电流与浓度在１．０×１０－４～１．５×１０－２μｇ／ｍＬ之间里线性关系，检测限为４．０×１０－５μｇ／ｍＬ．该法应用于人发及血清中痕量碲的测定，结果准确可靠．     

脱乙酰壳多糖化学修饰电极测定铂的研究

用脱乙酰壳多糖修饰电极为工作电极，阳极溶出伏安法测定痕量铂。在ｐＨ＝２￣３的ＫＣｌ－ＨＣｌ底液中，－０．３Ｖ富集２ｍｉｎ，静止１５ｓ，以０．２Ｖ／ｓ扫速阳极溶出，峰电位在－０．１６Ｖ（ｖｓ．ＳＣＥ），铂（Ⅳ）离子浓度在０．５￣５．０μｇ／ｍＬ范围内与峰高呈线性关系。富集１０ｍｉｎ后，可检测０．０２５μｇ／ｍＬ铂（Ⅳ）。该法用于贵金属矿样的测定，无需分离，结果满意。用循环伏安法、紫外光谱和拉曼光谱研     

无铅汽油中痕量铅的快速测定方法

研究了快速测定无铅汽油中痕量铅的方法。在４９０ｎｍ处,测定经氯化四乙胺的氯仿溶９液和碘溶液处理过的汽油与ＰＡＲ．２Ｎａ反应生成的络合物。线性范围为０－２５．２μｇ／ｍＬ,回归方程为Ａ＝０．０１２３４ｃ＋０．４１８８,相关系数为０．９９９２,检出限为０．２６μｇ／ｍＬ。本方法操作简便,测定一次可在２０ｍｉｎ内完成。     

催化极谱测定痕量铬的研究

本文研究了含氨介质中铬（Ⅲ，Ⅵ）－α，α－联吡啶－亚硝酸钠体系的电化学行为。建立了测定痕量铬的方法。测定铬的范围为０．００４－０．０２８μｇ／ｍＬ和０．０４－０．２８μｇ／ｍＬ，检测下限为２．０×１０＾－＾３μｇ／ｍＬ，用以测定生物样品中痕量铬，变异系数为９．８％。     

钴—H2O2—水杨基荧光酮反应体系的新催化动力学分析方法研究

在碱性介质中，痕量钴（Ⅱ）能显著催化Ｈ２Ｏ２氧化水杨基荧光酮的指示反应，本文据此建立了测定痕量钴的新催化动力学分析法，方法线性范围为０．１～２．８μｇ／Ｌ，检测限为０．０２μｇ／Ｌ。测得反应表现活化能为５９．０３ｋＪ／ｍｏｌ。测定了人发，茶叶，土壤和水等样品中钴的含量，结果满意。     

流动注射化学发光法测定痕量硫

基于硫离子对鲁米诺－过氧化氢化学发光反应的增敏作用,建立了测定痕量硫的流动注射化学发光反应的增敏作用,建立了测定痕量硫的流动注射化学发光的新方法。该方法的线性范围为２．０×１０－９～８．０×１０－７ｇ／ｍＬ,检出限为５．６×１０－１０ｇ／ｍＬ,相对标准偏差小于５％（１．０×１０－７ｇ／ｍＬＳ２－,ｎ＝１１）。方法简单,快速,灵敏,已用于环境水样中痕量硫的测定。     

泡沫塑料吸附—溶出计时电位法测定地质物料中痕量铊

本文提出了泡沫塑料吸附解脱新体系，建立了泡沫塑料吸附－溶出计时电位法测定地质物料中痕量铊的新方法。方法检出限０．０３μｇ／ｇ；铊的含量水平分别为０．７１μｇ／ｇ和１．６μｇ／ｇ时的测定精密度为３．４５％和３．２８％；工作曲线线性范围为５￣１５００ｎｇ／ｍＬ；回收率为９７．５％￣９８．０％。     

动力学光度法测定痕量镉的研究

本研究了氨水介质中，痕量镉阻抑过氧化氢氧化偶氮胂１褪色的新指示反应及其动力学条件，建立了动力学光度法测定痕量镉的新方法，方法检出限为２．７×１０＾－１２ｇＣｄ＾２＋／ｍｌ，测定范围为０－１．０μｇＣｄ＾２＋／２５ｍｌ。     

氧化藏红T褪色催化荧光法测定痕量钒

研究了在酸性介质中柠檬酸存在下，痕量钒（Ｖ）催化溴酸钾氧化藏红Ｔ的褪色反应及其动力学条件，建立了催化荧光测定痕量钒的新方法。催化反应在沸水浴中进行８ｍｉｎ，为假零级反应，反应的表观活化能力为９９．２１ｋＪ／ｍｏｌ，反应速度常数为０．１２／ｓ；该方法的检出限为２．２×１０＾－８ｇ／Ｌ；线性范围为０．２￣２．４μｇ／Ｌ研究了共存离子的影响，用于人发和煤灰中痕量钒的测定，结果令人满意。     

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.     

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.     

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.     

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.