KMnO4-乙二醛化学发光体系测定抗坏血酸

基于维生素C对KMnO4-乙二醛化学发光体系强烈的抑制作用,建立了维生素C的流动注射化学发光测定方法。在最佳测试条件下,方法的检出限为5×10-13 mol/L,线性范围为1.0×10-12～1.0×10-4 mol/L;对1.0×10-8mol/L的维生素C平行测定11次,其RSD为1.7%。该方法可应用于蔬菜、水果中维生素C含量的测定。     

KMnO4-甲醛化学发光体系测定对乙酰氨基酚

基于对乙酰氨基酚在酸性介质下对KMnO4-甲醛化学发光体系强烈的增敏作用,建立了对乙酰氨基酚的流动注射化学发光测定方法。在最佳测试条件下,方法对对乙酰氨基酚的检出限(S/N=3)为1.0×10-10mol/L,线性范围为1.0×10-9～1.0×10-5mol/L对乙酰氨基酚,相关系数R为0.9993;对1.0×10-6mol/L的对乙酰氨基酚溶液平行测定11次,其RSD为1.1%。该方法可应用于药物中对乙酰氨基酚含量的测定。     

溴酸钾-酸性铬蓝K化学发光法检测水中微量NO2-

利用NO2-对溴酸钾-酸性铬蓝K体系的化学发光有显著的增强作用,建立了检测亚硝酸盐的新方法。着重对化学发光条件,包括溴酸钾浓度、酸性铬蓝K浓度、管长、流速及酸度条件进行了实验研究,并利用该方法对地下水及当地雨水进行了检测。实验结果表明,当溴酸钾浓度为0.1 mol/L、酸性铬蓝K浓度为1.0×10-4mol/L、管长为40 cm、流速为2.5 mL/min及硫酸为0.5 mol/L时,本方法检测NO2-的线性范围为1.0×10-8~8.0×10-5mol/L,检出限为1.1×10-10mol/L;对1.0×10-7mol/L和1.0×10-5mol/L的NO2-进行11次平行测定,相对标准偏差分别为1.6%和2.1%;对天然水中NO2-检测,结果满意。对化学发光机理进行了初步探讨。     

溴酸钾-酸性铬蓝K新化学发光体系检测水中亚硝酸根

研究发现亚硝酸根对溴酸钾-酸性铬蓝K体系的化学发光有显著的增强作用,从而建立一种快速、准确的检测亚硝酸盐的新方法.本方法检测亚硝酸根的线性范围为1.0×10-8～8.0×10-5mol/L,检测限为1.1×10-10mol/L;对1.0×10-7mol/L和1.0×10-5mol/L的亚硝酸根进行11次平行测定,标准偏差分别为1.6%和2.1%.     

KMnO4-乙二醛化学发光体系测定阿魏酸

酸性介质下,KMnO4氧化阿魏酸产生化学发光,乙二醛对该体系有增敏作用。结合流动注射技术,建立了测定阿魏酸的流动注射化学发光新方法。该方法线性范围为1.0×10-7～2.0×10-5mol/L,检出限为1.0×10-8mol/L,对1.0×10-6mol/L的阿魏酸平行测定11次,相对标准偏差为2.8%。该法用于太太美容口服液中阿魏酸的测定,结果令人满意。     

流动注射化学发光法测定3种氟喹诺酮类药物

研究发现,氟喹诺酮类药物对可溶性Mn(-甲醛化学发光体系有强烈的增敏作用,结合流动注射技术,建立了3种氟喹诺酮类药物诺氟沙星、氧氟沙星和环丙沙星的流动注射化学发光新方法。在优化的实验条件下(2×10-4molMn(-3%甲醛-3mol/L磷酸),本方法测定诺氟沙星、氧氟沙星和环丙沙星的线性范围分别为1.0×10-7～1.0×10-5mol/L,1.0×10-7～1.0×10-5mol/L和3.0×10-7～5.0×10-5mol/L;检出限分别为3×10-8mol/L,3×10-8mol/L,1×10-7mol/L;相对标准偏差(5.0×10-6mol/L氟喹诺酮类药物,n=11)分别为2.6%,1.6%和2.8%。该方法已用于诺氟沙星胶囊中诺氟沙星的含量测定。     

流动注射化学发光法测定Mn(Ⅱ)

在酸性条件下,溴酸钾氧化鲁米诺产生化学发光,Mn2 对这一体系的化学发光具有增强作用.据此,结合流动注射技术,建立了一种测定Mn2 的新方法.线性范围为1.0×10-8～6.0×10-6 mol/L;检出限为8.0×10-9 mol/L (3σ);对1.0×10-6 mol/L的Mn2 进行了平行测定(n=11),其相对标准偏差为2.4%.该方法可用于矿泉水中Mn2 的测定.     

流动注射化学发光灵敏测定阿洛西林

基于阿洛西林对Luminol-KIO4化学发光体系的抑制作用,提出了一种流动注射-化学发光测定阿洛西林的快速、灵敏的新方法.在优化条件下,阿洛西林的线性范围是5.0×10-8～1.0×10-5 mol/L,检出限为3.1×10-8 mol/L.对1.0×10-7 mol/L阿洛西林进行11次测定,相对标准偏差为1.7％...     

流动注射化学发光法测定湖水中2-硝基酚

在酸性介质下,KMnO4可以氧化2-硝基酚产生化学发光,乙二醛对该发光体系有增敏作用。结合流动注射技术,建立了测定2-硝基酚的流动注射化学发光新方法。该方法线性范围为8.0×10-10～5.0×10-6 mol/L,检出限为1.0×10-11mol/L,对1.0×10-7 mol/L的2-硝基酚平行测定11次,相对标准偏差为2.4%。该法已用于实际水样中2-硝基酚的测定。     

流动注射化学发光法测定中药材中没食子酸

建立快速简便的流动注射化学发光分析法,用于中药材中没食子酸含量的测定.利用酸性介质中Fe3+-H2O2体系生成羟基自由基氧化没食子酸产生微弱的化学发光,用罗丹明6G来增敏化学发光.研究了影响化学发光的各种因素,探讨了可能的机理.结果表明,0.18 mol/L HCl,0.04 mol/L FeCl3,1.0 mol/L H2O2与1.0×10-4 mol/L罗丹明6G溶液组成最优的化学发光体系,没食子酸浓度在1.0×10-5～1.0×10-2 g/L和0.01～1.0 g/L范围内与化学发光强度呈很好的线性关系,r分别为0.9984和0.9947,检出限为3.0×10-6 g/L.对1.0×10-4 g/L没食子酸平行测定11次的相对标准偏差为3.8%.利用本方法成功地测定了中药材诃子和没食子中的没食子酸含量.     

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.