反相流动注射化学发光法测定黄芩苷

在碱性介质中,K3Fe(CN)6氧化鲁米诺产生化学发光,黄芩苷对该体系化学发光具有强烈的抑制作用。利用该化学发光的抑制体系,结合反相流动注射技术,建立了测定黄酮类药物黄芩苷含量的新方法。在优化的条件下,黄芩苷浓度在1.0×10-8～1.0×10-7和3.0×10-7～4.0×10-6mol/L范围内与化学发光抑制强度ΔI呈良好的线性关系,检出限为1.0×10-9mol/L,对3.0×10-7mol/L的黄芩苷进行平行测定10次,得相对标准偏差(RSD)为1.7%。该方法可应用于银黄口服液中黄芩提取物(黄芩苷计)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.     

鲁米诺-过硫酸钠体系后化学发光法测定银

邻菲罗啉存在下,银对鲁米诺-Na2S2O8体系的后化学发光具有增敏作用,建立了流动注射后化学发光测定银的新方法.在优化实验条件下,该法测定银的线性范围为1.0×10-9～4.0×10-7 mol/L,线性相关系数为0.9987(n =7),检出限为3.53×10-10mol/L(n=11),对1.0×10-7 mol/...     

双[2,4,6-三氯苯基]草酸酯-过氧化氢体系流动注射化学发光法检测地沟油中的胆固醇

基于胆固醇和冰乙酸的反应物与硫酸铁铵生成的紫色化合物能有效抑制双[2,4,6-三氯苯基]草酸酯(Bis(2,4,6-trichlorophenyl)oxalate,TCPO)-H2O2-咪唑化学发光反应,建立了流动注射-化学发光联用检测胆固醇的方法。对流动注射、化学发光等实验参数进行了优化。当咪唑浓度为0.001 mol/L,H2O2浓度为0.3 mol/L,TCPO浓度为1.0×10"3mol/L,主副蠕动泵转数分别为20和15 r/min时,体系具有最强的化学发光。在优化的实验条件下,测定胆固醇的线性范围为8.6×10"6～2.2×10"4mol/L;检出限(S/N=3)为2.5×10"6mol/L;相对标准偏差(RSD,n=11,c=6.5×10"5mol/L)为1.5%。不同加标水平下的加标回收率为95.0%～105.0%;相对标准偏差(n=6)小于3.6%。本方法已应用于地沟油中胆固醇的测定,结果令人满意。     

鲁米诺重氮化化学发光选择性测定水中的亚硝酸盐

基于重氮化鲁米诺与H2O2反应可产生增敏的化学发光信号,建立了一种新的对NO2-高选择性检测的化学发光方法。结合流动注射技术,方法测定NO2-的线性范围为4.8×10-8~4.8×10-6mol/L,线性相关系数R2=0.9994,检出限为1.5×10-8mol/L,相对标准偏差RSD=3.6%(2.4×10-7mol/L NO2-,n=11)。对已知亚硝酸盐含量的样品进行测定,与国家标准方法测定结果无显著性差异。方法已用于自来水及同水源锅炉水中NO-2的测定。     

流动注射化学发光增强法测定巯嘌呤的应用研究

试验发现6-巯基嘌呤对Luminol-H2O2-OH-体系的化学发光有较强的增敏作用。据此建立了一种流动注射化学发光增强法测定6-巯基嘌呤的新方法。该法测定6-巯基嘌呤的检出限为7.5×10-9mol/L,线性范围为2.0×10-8~2.5×10-6mol/L,对6.0×10-7mol/L的6-巯基嘌呤测定的相对标准偏差为1.6%(n=11),已用于合成样中6-巯基嘌呤的测定。     

表面活性剂增强铈-对乙酰氨基酚化学发光测定对乙酰氨基酚片

本文研究了表面活性剂对铈(Ⅳ)氧化对乙酰氨基酚化学发光反应的影响,发现了铈(Ⅳ)-吐温20-对乙酰氨基酚化学发光新体系,建立了测定对乙酰氨基酚化学发光的分析方法。在0.1 mol/L的H2SO4介质下,0.06 mol/L的硫酸高铈载液中,对乙酰氨基酚的浓度在8.0×10-8~1.0×10-4mol/L范围内与发光强度成良好的线性关系(r=0.9992,n=13),检出限为4.0×10-8mol/L。连续测定2.0×10-6mol/L的AP溶液7次,发光强度的RSD为1.0%。此方法简单、方便、灵敏,适合于在线分析。该法用于对乙酰氨基酚药片中对乙酰氨基酚的测定。     

鲁米诺-铁氰化钾流动注射化学发光法测定红葡萄酒中白藜芦醇的含量

基于白藜芦醇对鲁米诺-铁氰化钾化学发光反应的增敏作用,对其最佳反应条件进行了系统试验,并结合流动注射,提出了测定红葡萄酒中白藜芦醇含量的流动注射化学发光法。在1×10^-3 mol·L^-1氢氧化钠溶液中,鲁米诺溶液及铁氰化钾溶液的最佳浓度依次为8×10-6,2×10^-5 mol·L^-1。在此条件下,白藜芦醇的线性范围为1.00×10-8~1.00×10^-6 mol·L^-1,检出限(3S/N)为3.0×10^-9 mol·L^-1。对4.00×10^-7 mol·L^-1白藜芦醇标准溶液进行精密度试验,测定值的相对标准偏差(n=11)为2.6%。分析实际样品时,将红葡萄酒样品减压抽滤除去不溶性颗粒,取滤液50mL,煮沸2min,除去挥发性芳香物质,冷却后离心5min,取上清液按仪器工作条件进行测定。按此方法在样品的基础上进行加标回收试验,测得回收率为95.9%~130%。     

流动注射化学发光法测定水中的苯胺

基于在多聚磷酸介质中,KMnO4氧化苯胺能产生强化学发光,建立了流动注射化学发光测定苯胺的新方法.在优化条件下,化学发光强度ⅠCL与苯胺的浓度在2.0×10～1.0×10-6 mol/L范围内呈良好的线性关系,回归方程为ⅠCL=63.11 2.37×108c(r=0.9997,n=9),检出限为5.0×10-10 mol/L,对1.0×10-7 mol/L苯胺进行11次测定,其相对标准偏差为0.8%(n=11).已用于环境水体中苯胺的测定,回收率在95.1%～105.1%之间.     

流动注射化学发光抑制法测定阿魏酸钠

提出了Fe2+-H2O2-亚甲基蓝化学发光新体系并用于阿魏酸钠的测定。实验发现,在酸性介质中,Fe2+-H2O2体系可与亚甲基蓝反应产生极强的化学发光,阿魏酸钠对此化学发光具有显著的抑制作用。据此,结合流动注射技术,建立了阿魏酸钠化学发光分析新方法。研究了影响化学发光强度的因素,化学发光信号的降低值(ΔI)与阿魏酸钠浓度在4.5×10-6～4.5×10-5mol/L范围内呈良好的线性关系,方法的检出限为7.0×10-7mol/L。对4.8×10-6mol/L的阿魏酸钠进行了11次平行测定,其RSD=0.8%,该法已用于片剂中阿魏酸钠含量的测定。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

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.