动力学荧光法测定痕量对苯二酚

基于在硫酸介质中，对苯二酚能活化钒（V）催化溴酸钾氧化吖啶橙的反应，使其荧光猝灭，建立了动力学荧光法测定痕量对苯二酚的新方法。研究了体系的动力学条件，采用固定时间法测定荧光猝灭程度。方法线性范围为2-40μg/L，检出限为1.15μg/L。用于水样、显影废液中对苯二酚的测定，结果满意。初步探讨了反应机理。     

溶解态菲及其中间代谢产物1-羟基-2-萘甲酸的同时测定

运用导数-同步荧光光谱建立了快速同时测定溶解态菲(Phenanthrene,Phe)及其中间代谢产物1-羟基-2-萘甲酸(1-Hydroxy-2-naphthoic acid,1H2NA)的分析方法。所建方法同时测定Phe与1H2NA的线性范围分别为4.0~1.0×103μg/L和4.0~1.2×103μg/L,检出限分别为0.08μg/L和0.07μg/L,加标回收率分别为96.5%~105.3%和99.2%~106.5%,相对标准偏差均小于1.0%。该方法可应用于实验室条件下溶解态Phe微生物降解过程中Phe和1H2NA的测定,具备原位研究Phe降解过程中间代谢产物1H2NA的应用潜力。     

基于荧光素汞荧光法结合光纤传感-微顺序注射-阀上实验室测定肠灌流液中H2S

建立基于光纤传感技术结合微顺序注射-阀上实验室荧光猝灭测定肠灌流液中H2S含量方法。本研究进行单因素考察,确定以100μL 0.1mol/L Na OH溶液为载液,荧光素汞浓度为5.0×10#5mol/L、体积50μL、进样体积50μL、流通池检测流速25μL/s,根据H2S猝灭荧光素汞521 nm处荧光,对样品中H2S浓度进行测定。本方法检测H2S的浓度范围为5.0×10#6~8.0×10#5mol/L,检出限为5.4×10#7mol/L。测定肠灌流液中H2S含量为3.8×10#5mol/L,RSD=3.1%(n=3)。本方法能有效在线测定样品中H2S含量,为实时在线测定生物样品中的H2S含量奠定基础。     

罗丹明6G荧光猝灭法测定中草药中微量铁

在H2SO4溶液中,Fe3 与过量KI反应后生成I3-阴离子,I3-与罗丹明6G形成离子缔合物,并使罗丹明6G发生荧光猝灭,据此建立了测定Fe3 的荧光猝灭分析方法。方法的线性范围为20~200μg/L,检出限为8.3μg/L,用于中草药中铁的测定。     

溴酸钾氧化酚藏花红动力学荧光法测定痕量甲醛

在H2SO4介质中,痕量甲醛能显著地催化溴酸钾氧化酚藏花红的反应,使体系的荧光强度减弱,据此建立了动力学荧光法测定甲醛的新方法。在最佳实验条件下,方法的线性范围为8.0～400μg/L,检出限为3.1μg/L。该法简便、快速、选择性好,已用于环境水样中痕量甲醛的测定,其加标回收率在97.5%～103%之间,相对标准偏差为2.9%～3.4%。     

阻抑荧光猝灭法测定环境水样中痕量砷

在H2SO4介质中,KIO4氧化吖啶黄,使体系褪色并伴随荧光猝灭,痕量的As(Ⅲ)能显著阻抑此反应,据此建立了一种新的荧光法测定痕量As(Ⅲ)。本文对该体系的实验条件进行了详细研究。在最佳条件下,方法的线性范围为5.0～400μg/L,检出限为2.4μg/L。方法已用于环境水样中痕量As(Ⅲ)的测定,加标回收率为94.2%～102.6%。     

动力学荧光分析法测定间苯三酚的研究

基于在稀H2SO4介质中,痕量间苯三酚对高碘酸钾氧化罗丹明B具有显著的催化作用,使溶液的荧光猝灭,建立了动力学荧光法测定间苯三酚的新方法。方法的线性范围为0.80~800.0μg/L,检出限为0.40μg/L。本法用于针剂中的间苯三酚含量的测定,结果满意。     

动力学荧光分析法测定间苯三酚

基于在稀H2SO4介质中,间苯三酚对铜催化H2O2氧化吡口罗红B使其荧光猝灭具有显著的活化作用,建立了测定痕量间苯三酚的动力学荧光分析的新方法.反应在100 ℃的恒温水浴中进行5 min,方法的线性范围为0.8～800.0 μg/L,检测限为0.41 μg/L,回收率为98.3%～103.2%.该方法用于测定注射液中痕量间苯三酚.     

流动注射时间扫描荧光分析法测定青霉素V钾

研究了H2SO4颜色反应用于青霉素V钾(PMPP)荧光测定的新方法。PMPP为弱荧光物质,与浓H2SO4反应后荧光显著增强。结合流动注射进样技术,借助时间扫描荧光方式,提出了流动注射时间扫描荧光分析法测定PMPP的新方法。在最大激发236.0 nm、最大发射波长306.0 nm处,PMPP在3.6×10-5g/L~4.0×10-2g/L范围内与荧光强度呈良好的线性关系,相关系数为0.9999。方法检出限为1.0×10-5g/L,相对标准偏差为0.6%(n=11,ρ=1.0×10-3g/L),进样量为0.18 mL。方法已用于药物及尿样中PMPP的测定。     

氧化酸性铬蓝K褪色动力学光度法测定微量芦丁

基于2 mmol/L的H2SO4介质中,微量芦丁催化H2O2氧化酸性铬蓝K(ACBK)的褪色反应,建立了测定微量芦丁的动力学光度法。方法的检出限为1.08μg/L,线性范围为3.6~400μg/L。实验讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响,确定了该体系反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为73.22 kJ/mol。在25 mL溶液中,测定10.0μg芦丁的相对标准偏差为1.6%(n=11)。方法用于测定槐米和芦丁片剂中的芦丁,相对标准偏差为1.0%~1.1%,标准加入回收率为98.0%~101.7%。     

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.     

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.     

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.