基体分离-电感耦合等离子体质谱法测定高纯硒中13种杂质元素

采用基体分离-电感耦合等离子体质谱法（ICP-MS）测定高纯硒中13种痕量杂质元素含量,优化了试验条件.利用二氧化硒在真空条件下升华温度低的特点挥发基体硒,选择合适的内标元素,考察基体效应的影响.结果表明,选择Cs作为待测元素的内标更合适.测定硒残留量小于100 μg/mL的样品,不影响各待测元素.方法检出限为0.007~0.033 μg/g,RSD为5.7%~19%,加标回收率在90.2%~115%之间,可以满足高纯硒中痕量杂质元素含量的测定.     

硝酸铅沉淀/ICP-MS法测定高纯铅中18种杂质

通过硝酸铅沉淀分离基体铅、有效富集高纯铅中镁、铝、钙、铁、镍、钴、锰、铜、锌、砷、硒、镉、铟、锡、锑、碲、铊、铋等18种杂质,通过电感耦合等离子体质谱测定高纯铅中18种杂质,测定下限在0.04～0.32μg/mL,加标回收率为80%～108%,测定精密度(RSD)为2.5%～14%。     

石墨炉原子吸收法测定高纯硒中痕量铁

研究了石墨炉原子吸收直接进样法和石墨炉内富集法测定高纯硒中痕量铁的条件,建立了石墨炉原子吸收法直接测定高纯硒中痕量铁的分析方法.直接进样法的检出限为0.008 μg/g,石墨炉内富集法的检出限为0.004 μg/g,相对标准偏差分别为:5.2%和4.6%,两种方法检测样品结果基本一致.测定含铁0.3 μg/g的高纯硒,测定值的RSD为4.6～5.2%.     

共沉淀分离-ICP-MS测定高纯阴极铜中硒和碲

研究了采用共沉淀分离手段在氨性条件下分离大量铜基体并富集痕量硒、碲杂质的实验条件。优化选择了共沉淀剂的种类、浓度、氨水用量和温度等条件,考察了内标元素、铜残留浓度对ICP-MS测定的影响。与直接测定法相比,硒碲被富集了50倍,建立了共沉淀分离-ICP-MS测定高纯阴极铜中硒碲的方法。硒碲测定下限分别为0．08和0．10μg／g,RSD〈10％,加标回收率在90％-115％之间。方法已用于实际样品分析。     

电感耦合等离子体发射光谱法测定高纯稀散金属中杂质元素研究进展

综述了电感耦合等离子体发射光谱法测定高纯稀散金属中镓、铟、铊、锗、硒、碲、铼中杂质元素的研究进展,分析了样品测定过程与重点,分别对镓、铟、铊、锗、硒、碲、铼进行了介绍,重点讨论了基体的干扰和消除,并对测定高纯稀散金属中杂质元素的发展方向提出建议。     

ICP-AES分析高纯氧化镥中痕量稀土杂质的研究

使用ICP光源和倒数线色散率4.5A/wm的平面光栅摄谱仪,研究不同型的同心气动雾化器的雾化效率、乙醇的影响及电感耦合等离子体发射光谱分析的有关条件。Lu_2O_3溶液浓度为10mg/ml,用LB喇叭型雾化器引入光源中,获得15个稀土杂质的测定下限为0.1～5μg/g。本方法的相对均方偏差为4.6～12.8％,加料回收率为88～117％。方法适用于纯度为99.996％高纯Lu_2O_3中稀土杂质的分析。     

氢化物发生-原子荧光光谱法测定高纯阴极铜中硒、碲

本文报道了采用氢化物发生-原子荧光光谱法(HG-AFS)测定高纯阴极铜中硒、碲。实验考察了盐酸、三氯化铁的浓度对氢化物发生效率的影响,探讨了铜和其它共存元素的干扰情况。该法测定硒、碲的检出限分别为0.27μg/L、0.11μg/L,加标回收率分别为94.9%～114.0%、91.8%～105.3%,精密度为1.5%～7.8%。     

三重串联电感耦合等离子体质谱法直接测定高纯氧化钕中14种稀土杂质元素

建立了三重串联电感耦合等离子体质谱(ICP-MS/MS)法直接测定高纯钕中的14种稀土杂质元素的方法.采用氧气和氨气反应池在串联质谱MS/MS模式,有效克服了基体对待测元素的干扰.通过优化仪器参数得到Tb,Dy和Ho的背景等效浓度分别为22,40和4 ng/L.在选定的条件下,样品加标0.5 μg/L14种混合稀土标样测得的回收率为88.6％ ～ 98.6％,使用仪器标准配置的耐高盐进样系统(HMI)测得2h信号值的相对标准偏差(RSD)为1.3％-4.1％.本方法简单实用,能够满足纯度为5N (99.999％)及以上的高纯钕中14种杂质元素的直接测定.     

氢化物原子荧光光谱法测定水中微量砷和硒

研究了氢化物发生-原子荧光光度法测定水中微量砷和硒的方法。结果表明,检出限:砷为0.0518μg/L,硒为0.0524μg/L;11次测定的相对标准偏差为0.36％～0.62％;标准回收率:砷为96.8％～100.9％;硒为95.9％～103.7％。方法简便、快速、灵敏,适于生活饮用水、地表水和水源水中微量砷、硒的同时测定。     

等离子体质谱多内标法测定金属铒中多种痕量元素

本方法采用ICP—MS法同时测定高纯金属铒中14个稀土元素和15种非稀土元素杂质，确定了合适的样品稀释浓度，采用Sc、In、Cs、Tl4个内标，杂质元素的检出限在0．04～16μg／g之间，样品的加标回收率在86％～105％之间，能够满足4N金属铒产品的检测需求。     

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.