铜(Ⅱ)催化铍试剂还原反应的动力学及其应用

在 2 ,2′-联吡啶的存在下 ,铜 ( )催化抗坏血酸还原铍试剂 的反应。考察了影响反应的条件 ,讨论了反应机理 ,建立了测定超痕量铜的新方法。方法的检出限是1 .2 7× 1 0 - 11g/m L ,测定范围是 0 .0 0～ 1 .0 0 ng/m L。本法已用于自来水和矿泉水中痕量铜 ( )的测定     

阻抑动力学光度法测定白鼠肝脏中的超痕量镍(Ⅱ)

在 NH3- H2 O- NH4 Cl介质中 ,超痕量镍 ( )能阻抑 H2 O2 氧化甲基紫褪色的指示反应 ,研究了阻抑褪色反应的最佳条件和动力学参数 ,建立了测定超痕量镍 ( )的新方法。方法检出限为 4.4× 1 0 -11g/m L Ni( ) ,测定范围为 0～1 .0μg/2 5m L。方法已用于测定生物样品中的 Ni( )。     

DCB-偶氮胂高灵敏光度法测定痕量铬(Ⅵ)

本文研究了 DCB偶氮胂与 Cr2 O2 - 7的褪色反应。结果表明 ,在硝酸介质中褪色反应具有高的灵敏度 ,拟定了反应的最佳条件 ,建立了一种新的光度法测定痕量铬( )方法。本法检出限为 4.2 2× 1 0 - 11g/m L ,线性范围为 0～ 0 .8μg/1 0 m L ,用于测定人发中的痕量铬 ( ) ,结果令人满意     

测定超痕量铁的高灵敏指示反应

在稀 H2 SO4 介质中 ,1 ,1 0 -邻菲 口罗啉存在下基于 Fe( )催化过氧化氢氧化棉红的新指示反应建立了测定超痕量铁的一个新方法。方法检出限 1 .0× 1 0 - 11g/m L ,线性范围 0 .0 0～ 1 .2 ng/m L。用于井水、一次蒸馏水、黄豆、芹菜中痕量及超痕量铁的测定获得满意结果     

聚酰胺分离富集催化动力学光度法测定痕量金

研究了在稀硫酸介质中 ,痕量金催化溴酸钾氧化偶氮氯膦 褪色的指示反应及其动力学条件 ,据此建立了测定痕量金 ( )的新方法。方法的检出限为 1 .1 2×1 0 - 11g/m L,测定范围为 0～ 1 .0 μg/1 0 m L。采用聚酰胺在盐酸或王水介质中分离富集矿样中的金后 ,用拟定的方法测定获得满意结果     

阻抑动力学光度法测定痕量钛(Ⅳ)

在硫酸和聚乙烯醇溶液中 ,钛 ( )能抑制 Fe( )催化 H2 O2 氧化中性红褪色 ,研究了该反应的最佳条件和动力学参数 ,据此建立了一种测定痕量钛( )的新方法 ,方法检出限为 7.5× 1 0 -2 μg/m L ,测定范围为 0 .0 6～ 0 .60μg/m L,可用于人发中 Ti( )的测定。     

丁基罗丹明B—溴酸钾催化动力学体系光度法测定痕量络

在硫酸介质中 ,微量铬 ( )能显著催化溴酸钾氧化丁基罗丹明 B褪色。研究了该指示反应的动力学行为 ,建立了测定痕量铬的新的催化动力学分析方法。方法的线性测定范围为 0 .0 4～ 2 .0 μg/2 5 m L,检出限为 9.68× 1 0 - 10 g/m L。本法用于电镀废水中 Cr( )的测定 ,结果满意     

水杨醛缩氨基硫脲的合成及其与镉荧光熄灭反应

1　引　　言合成了水杨醛缩氨基硫脲并研究了其与镉离子荧光熄灭反应的最佳条件 ,利用萃取分离技术提高了方法的选择性和灵敏度 ,测定镉离子的线性范围为 0 .0～ 3 0 .0 μg L,检出限为 1 .4μg L ,是目前荧光法测定镉离子最灵敏的方法之一。该方法成功地应用于小麦样品中痕量镉的测定。2　实验部分2 .1　仪器及试剂　RF 5 40型荧光分光光度计 (日本岛津公司 ) ;PHS 3C型酸度计 (上海雷磁仪器厂 )。 0 .1 0 0g L的镉离子标准溶液 ,用时逐级稀释至 0 .2 5mg L ;2 .5× 1 0 - 4mol L的水杨醛缩氨基硫脲 (自合成 )乙醇溶液 ;pH =7.9的 0 .…     

巯基葡聚糖分离富集催化动力学荧光猝灭法测定痕量镉

痕量组分镉的测定对于工业、环境、健康有着重要的意义。研究了在pH=5.2邻苯二甲酸氢钾-NaOH介质中,痕量镉催化H2O2氧化3-(4′-氟苯基)-5-(2′-羧基苯偶氮)若丹宁,而荧光猝灭存在明显的催化作用,由此建立了动力学荧光法测定痕量镉的新方法。该体系的激发和发射波长分别为λex/λem=307nm/408nm,通过实验测定反应表观活化能为59.06kJ/mol;反应速率常数为0.101s-1;线性范围为0~10.0μg/L;检出限为3.9×10-7g/L。采用巯基葡聚糖凝胶分离富集,消除了共存离子的干扰,显著提高了方法的选择性和灵敏度。本方法应用于食品和人发中镉的测定获得满意的结果。     

锌试剂和高碘酸钾反应动力学测定超痕量锰

在 p H4.74的 HAc- Na Ac缓冲溶液中 ,以氨三乙酸为活化剂 ,KIO4 氧化锌试剂的反应受 Mn( )的催化加速 ,从而建立了测定超痕量锰的新方法。研究了影响反应速率的条件 ,测定了反应的表观活化能及表观速率常数。该法的检出限为 2 .4× 1 0 -11g/m L,测定范围是 0 .0～ 2 0 ng/1 0 m L。可用于蒸馏水中超痕量锰及大豆、面粉中痕量锰的测定     

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%.     

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.