大蒜中抗坏血酸的半微分伏发法测定

将工作电极直接插入大蒜瓣中，采用半微分伏安法研究了抗坏血酸的测定方法。用微铂盘电极作为工作电极，在ｐｈ６．８的磷酸氢二钠－柠檬酸介质中，抗坏血酸在７．０×１０＾－２－３．２×１０＾２ｍｇ／Ｌ范围内与半微分伏安曲线阳极峰的峰高呈线性关系，其最低检出浓度为４．９×１０＾２ｍｇ／Ｌ。     

高锰酸钾—抗坏血酸化学发光体系测定抗坏血酸

本文研究了高锰酸钾－抗坏血酸化学发光体系，建立了测定抗坏血酸的化学发光分析新方法，线性响应的浓度范围为５．０×１０＾－７ｍｏｌ／Ｌ～４．０×１０＾－５ｍｏｌ／Ｌ，检出限为３．０×１０＾－７ｍｏｌ／Ｌ，对２．５×１０＾－６ｍｏｌ／Ｌ抗坏血酸进行１０次平行测定，相对标准偏差为１．６％，考察了２２种物质的干扰情况。用于维生素Ｃ片剂及注射液中抗坏血酸含量测定，结果令人满意。     

高锰酸钾－抗坏血酸化学发光体系测定抗坏血酸

本文研究了高锰酸钾－抗坏血酸化学发光体系，建立了测定抗坏血酸的化学发光分析新方法。线性响应的浓度范围为５．０×１０￣（－７）ｍｏｌ／Ｌ～４．０×１０￣（－５）ｍｏｌ／Ｌ检出限为３．０×１０￣（－７）ｍｏｌ／Ｌ对２．５×１０￣（－６）ｍｏｌ／Ｌ抗坏血酸进行１０次平行测定，相对标准偏差为１．６％。考察了２２种物质的干扰情况。用于维生素Ｃ片剂及注射液中抗坏血酸含量测定，结果令人满意。     

碘离子选择电极检测催化动力学分析法测定抗坏血酸

在稀硫酸介质中，痕量去氢抗坏血酸对Ｖ（Ｖ）－ＢｒＯ３＾－－Ｉ＾－反应有强烈的催化作用，体系中Ｉ＾－浓度的变化可供碘离子选择电极跟踪检测。据此，本文建立了测定６×１０＾－７￣２×１０＾－５ｍｏｌ／Ｌ抗坏血酸的催化动力新分析法，用于实际样品分析获得较好结果。     

掺磷钼杂多酸聚吡咯修饰铂微电极对抗坏血酸的电催化氧化

本文报道了掺磷钼杂多酸的聚吡咯修饰电极的制备方法，伏安行为及其对抗坏血酸的电催化效应，该膜电极性能稳定，对抗坏血酸的电催化效果好，抗坏血酸浓度在５×１０＾－７－１．０×１０＾－４范围内与峰电流有良好的线性关系，用于测定和蔬菜和水果中抗坏血酸获得满意结果。     

伏安型植物组织生物微电极的研究：混合不同植物组织碳糊微电极的研究

由于香蕉组织中含有的氧化酶能够生物催化氧化多巴胺，去甲肾上腺素，Ｌ－多巴等，大大地提高了植物组织电极的灵敏度；又由于茄子组织中所含有的氧化酶在催化氧化儿茶酚的同时，能有效地抑制抗坏血酸在电极上的反应，将上述两种植物组织混合制成电极，使其更适于神经递质的测定，线性范围：２．４×１０＾－６－－９．８×１０＾－４ｍｏｌ／Ｌ；检出下限３．２×１０＾－７ｍｏｌ／Ｌ。     

钴—5,10,20—四（3—甲氧基—4—羟基苯基）卟啉修饰玻碳电极的L—抗坏血…

将水合５，１０，１５，２０－四－（３－甲氧基－４－羟基苯基）钴卟啉修饰在玻碳电极表面，制成ＣｏＴＭＨＰＰ修饰电极，电极稳定性好且灵敏度高，对抗坏血酸有良好的电催化氧化作用，测定线性响应范围为１．０×１０＾－５－１．０×１０＾－２ｍｏｌ／Ｌ，响应时间小于１２ｓ。本研究了电极的性质和应用，并用于药物中抗坏血酸的测定，其测定结果与碘量法一致。     

高灵敏反相流动注射化学发光法测定抗坏血酸

基于抗坏血酸对Ｆｅ２＋－Ｌｕｍｉｎｏｌ－Ｏ２体系化学发光的抑制效应，利用反相流动注射技术，建立了一个测定抗坏血酸的高灵敏化学发光新方法。该法检出限达２×１０－１０ｇ／ｍＬ；抗坏血酸浓度在 １×１０－９～１× １０－６ｇ／ｍＬ范围内与体系化学发光强度减小量呈良好线性相关；相对标准偏差为１．９％（Ｃ＝５×１０－８ｇ／ｍＬ，ｎ＝１１）。     

硫辛酸修饰碳纤维微电极在抗坏血酸共存下选择性测定神经递质多巴胺

本研究了硫辛酸修饰电化学活化碳纤维电极。此电极在测定脑神经递质多巴胺（ＤＡ）时，具有较高的灵敏度和较好的选择性，它能够有效地消除抗坏血酸（ＡＡ）的干扰。该电极测定多巴胺的线性范围为１×１０＾－８－１×１０＾－５ｍｏｌ／Ｌ；检出下限为５×１０＾－９ｍｏｌ／Ｌ。     

2-氨基吡啶修饰电极的电化学性质及对抗坏血酸的测定

研究了２－氨基吡啶聚合膜修饰玻碳电极的制备及其电化学性质,并用于抗坏血酸（ＡＡ）的测定。在ｐＨ５．７ＢＲ缓冲溶液中,ＡＡ在 ２－氨基吡啶修饰电极上产生一灵敏的氧化峰,峰电流与ＡＡ浓度在４ × １０－６～１０－３ｍｏｌ／Ｌ范围内呈良好的线性关系,检测下限为 １．３ × １０－６ｍｏｌ／Ｌ。该电极对 ＡＡ有增敏作用,对多巴胺（ＤＡ）有排斥作用,重现性良好,可用于ＡＡ的测定。     

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.