溴酸钾氧化偶氮胂动力学光度法测定钯

根据在稀 H2 SO4 介质中 ,痕量钯 ( )对溴酸钾氧化偶氮胂 褪色反应的显著的催化作用 ,建立了测定痕量钯的催化动力学光度法。方法检出限为 0 .1 3μg/L,测定范围为 0～ 8.0 μg/L。可用于矿石中痕量钯的测定。     

溴酸钾氧化偶氮砷Ⅲ动力学光度法测定钯

根据在稀H2SO4介质中,痕量钯（Ⅱ）对溴酸钾氧化偶氮胂Ⅲ褪色反应的显著的催化作用,建立了测定痕量钯的催化动力学光度法。方法检出限为0．13μg/L,测定范围为0－8．0μg/L。可用于矿石中痕量钯的测定。     

溴酸钾氧化偶氮胂Ⅲ动力学光度法测定钯

根据在稀 H2SO4 介质中,痕量钯(Ⅱ)对溴酸钾氧化偶氮胂Ⅲ褪色反应的显著的催化作用,建立了测定痕量钯的催化动力学光度法。方法检出限为 0.13 μg/L,测定范围为 0～8.0 μg/L。可用于矿石中痕量钯的测定。     

荧光动力学法测定痕量钯

基于在硫酸介质中痕量钯离子对过氧化氢氧化罗丹明6G的催化作用,建立了动力学荧光法测定痕量钯的方法,方法的检出限为0．0183ug.ml^-1,线性范围为0．04－0．48ug.ml^-1,将方法用于合成样品中钯的测定,结果满意。     

催化动力学光度法测定微量钯

在硫酸 ( 1 + 1 )介质中 ,Pd(Ⅱ )催化过氧化氢氧化酸性铬蓝K的褪色反应。研究了反应的最佳条件 ,建立了催化光度法测定痕量钯的新方法。方法的最低检测限为 5 97× 1 0 - 4 μg/mL。线性范围为 5 97× 1 0 - 4 ～ 2 60× 1 0 - 2 μg/mL。该法用于合成样品和含钯催化剂的分析     

溴酸钾—偶氮氯膦Ⅲ—硫酸体系催化光度法测定钯

研究了在0.45mol·L~(-1)H_2SO_4介质中,痕量钯催化溴酸钾氧化偶氮氯膦Ⅲ这一新指示反应的动力学条件。建立了催化光度法测定钯的新方法。测定范围为0～0.4μg/25ml,摩尔吸光系数为4.8×10~6。用于合成样品及含钯催化剂的分析,结果满意。     

微波消解和固相萃取光度法测定氰化渣中痕量钯

根据 2_(2_喹啉偶氮 )_5_二甲氨基苯甲酸 (QADMAB)与钯的显色反应及C18固相萃取小柱对显色络合物的固相萃取 ,并结合微波消解样品 ,建立了一种测定氰化渣中痕量钯的方法。即在pH为 3 5的HAc_NaAc缓冲介质中 ,溴化十六烷基三甲胺 (CTMAB)存在下 ,QADMAB与钯反应生成 2 1稳定络合物 ,该络合物可被C18小柱萃取富集 ,富集的络合物用乙醇洗脱后用光度法测定 ,在乙醇介质中体系λmax=63 0nm ,ε=1 2 0× 1 0 5L·mol-1·cm-1。钯含量在 0 0 1～ 1 5mg L内符合比尔定律 ,方法用于氰化渣中钯含量的测定 ,结果令人满意。     

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( )。     

二甲基黄催化动力学光度法测定痕量钯

根据在 H2 SO4 介质中钯 ( )催化高碘酸钾氧化二甲基黄的褪色反应 ,提出了测定钯的新催化光度法。钯浓度在 0 .0～ 6.0μg/2 5 m L范围内与催化反应速率呈良好的线性关系。方法的检出限为 2 .1 9× 1 0 - 3μg /m L。对 3.0μg/2 5 m L钯 ( )测定的相对标准偏差为 0 .78% ( n=1 1 )。此法用于某些催化剂中钯的测定 ,标准加入回收率为 99.5 %～ 1 0 4 .1 %。     

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     

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.