Rapid Determination of Guanidine Nitrate by Single - point Titration

报道了以S－十二烷基双硫腙－苦味酸为载体制备苦味酸根离子电极,研究了电极的性能,并以该电极为指示电极研究了硝酸胍的单点滴定分析,导出了定量关系式。以0.1000mol/L标准硝酸胍溶液滴定0.1000mol/L苦味酸,控制滴定至95％,10次实验的平均值为0.1002mol/L,相对标准偏差为0.24％,滴定至90％～95％相对标准偏差小于0.3％。用该法进行工业硝酸胍含量分析,数分钟就能完成,结果与重量法很好吻合。     

兴奋剂马钱子碱的电化学氧化及其伏安法测定

以玻碳电极为工作电极，硫酸钾为支持电解质，在合适的ｐＨ条件下，通过循环伏安法，首次观测到了马钱子碱的不可逆氧化峰。在浓度为２０×１０－４～４０×１０－３ｍｏｌ／Ｌ范围内其峰电流与浓度呈线性关系，检测限为１０×１０－５ｍｏｌ／Ｌ。在正常人体的尿样中，采用标准加入法进行回收实验，其平均回收率为１００８％。该法简便、快速，用５０×１０－４ｍｏｌ／Ｌ的马钱子碱溶液重复测定１０次，相对标准偏差为１８％。对其反应机理作了初步探讨。     

Nafion修饰玻碳电极测定痕量地尔硫Zhou的研究

本以玻碳电极为基体，制备了Ｎａｆｉｏｎ修饰电极，研究了非电活性阳离子药物地尔硫Ｚｈｏｕ在该电极上的测定原理及方法，将地尔硫Ｚｈｏｕ加入到含电活性阳离子药物多巴胺的电解质溶液中，使多巴峰电流下降，峰电流的降低与地尔硫Ｚｈｏｕ的浓度对数在１．２×１０＾－７－８．０×１０＾－６ｍｏｌ／Ｌ范围内呈良好线性关系。本方法检测下限为６．２×１０＾８ｍｏｌ／Ｌ；回收率范围为９５．８％－１０４．９％；相对标准偏差     

长链烷基锍脲衍生物用作阴离子选择电极膜载体

合成了一系列长链烷基锍脲类衍生物，用作阴离子选择电极的新型载体，其中以十六烷基丙烯基锍脲苦味酸盐为载体的ＰＶＣ膜电极性能量佳，线性范围为１．０×１０＆－＾２－３．９×１０＾－＾７ｍｏｌ／Ｌ，检测下限为２．７×１０＾－＾７ｍｏｌ／Ｌ苦味酸根离子，测试了电极的选择性，并用十八烷基苯基锍脉苦味酸根电极电位滴定小蘖碱。     

微型镉柱还原分光光度法测定血清中一氧化氮

建立了微型镉柱还原法间接测定血清中一氧化氮的新方法。本方法还原硝酸根所需时间短，还原率达９５％以上，用于测定混合血清中一氧化氮。检测范围为０－１０００μｍｏｌ／Ｌ，相对标准偏差为１．７０％－２．４９％，对ＮＯ＾－３的回收率为９５．８％－１０４．０％，对ＮＯ＾－２的回收率为９３．６％－９６．８％。     

用流动注射法研究巯基化合物-铈(Ⅳ)-氢化可的松的化学发光反应

采用流动注射法研究了巯基化合物－铈（Ⅳ）－氢化可的松（ＨＣＲｓ）体系的化学发光行 为，对影响化学发光强度的诸因素进行试验和探讨，建立了流动注射化学发光法检测谷胱甘 肽（ＧＳＨ），半胱氨酸（Ｃｙｓ）等含巯基化合物的新方法。检测ＧＳＨ和Ｃｙｓ和线性范围分别为 ２．０×１０－６～１０．０×１０－５ｍｏｌ／Ｌ和１．０×１０－６ｍｏｌ／Ｌ～１０．０×１０－５ｍｏｌ／Ｌ；检测限分别为２．０ ×１０－７ｍｏｌ／Ｌ和１．４×１０－６ｍｏｌ／Ｌ（Ｓ／Ｎ＝３）；ＧＳＨ、Ｃｙｓ加入血清中进行回收测定的回收率 为９０％～９５％，相对标准偏差小于４％。     

聚苯胺／聚乙烯醇载体尼古丁膜电极的研究

聚苯胺／聚乙烯醇复合物与四苯硼钠－尼古丁混合，制成尼古丁膜电极，在ｐＨ＝２～７电极时１０＾－２～１０＾－５ｍｏｌ／Ｌ的尼古丁有良好的线性响应，检测下限可达４．０×１０＾－６ｍｏｌ／Ｌ。用于烟草样品中尼古丁含量的测定，平均回收率为９８．４％，相对标准偏差为０．９３％，与紫外分光光度法对比，结果令人满意。     

氟哌酸离子选择电极的研制及应用

本采用正交设计法，研究了离子缔合物种类，活性物在膜相中的浓度及增塑剂三因素对电极性能的影响，研制了稳定性和重现性良好的氟哌酸石墨内导ＰＶＣ膜电极。电极的线性响应范围为１０＾－２－１０＾－５ｍｏｌ／Ｌ；检测下限可达２．５×１０＾－６ｍｏｌ／Ｌ。电极直接用于胶囊含量测定，平均回收率９９．３６％；相对标准偏差０．８５％。与药典法比较，结果基本一致。     

18—冠—6修饰碳糊电极测定定金的研究

本文研究了１８－冠－６修饰碳糊电极测定金的条件，金在０．５ｍｏｌ／Ｌ ＨＣｌ－０．００５ｍｏｌ／Ｌ ＫＣｌ底液中富集，介质交换到０．０１ｍｏｌ／Ｌ ＨＣｌ中进行测定。金（Ⅲ）浓度在０．１～１．０μｇ／ｍＬ范围内呈线性关系，相对标准偏差为９．７％，检出限为２０ｎｇ／ｍＬ。可不经预先分离直接测定矿样中的金，结果良好。并研究了Ａｕ（Ⅲ）在１８－冠－６碳糊修饰电极上的还原机理。     

生物大分子肝素修饰电极的制备及其应用——痕量铜的测定

本文利用肝素与某些金属离子之间强烈的亲和作用，设计成了一种新型的伏安传感器，这处用肝素修饰的玻碳电极被用于前量铜的阳极溶出伏安测定。该电极制作简便，具有较好的重现性，选择性和较高的灵敏度，本方法测定铜的线性范围为２．０×１０＾－８ｍｏｌ／Ｌ～１．０×１０＾－６ｍｏｌ／Ｌ，检测下限为１．０×１０＾－９ｍｏｌ／Ｌ，同一支修饰电极平行测定１０次的相对标准偏差是３．２０％。     

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.