原子荧光光谱法测定城市污水中的铅

研究了用氢化物原子荧光法测定城市污水中铅的方法。对样品前处理方法进行了筛选,在选定的最佳实验条件下,方法检出限为０．５５μｇ／Ｌ。标样含量在２５μｇ／Ｌ时,其变异系数为０．３％。以实际样品测定,加标回收率为９６％－１０１％,变异系数在２％以内,证明本方法测定污水中的铅切实、有效。     

用氢化物—原子荧光法测定水处理剂中微量铅

对氢化物－原子荧光法测定水处理剂聚合氯化铝和硫酸铝中铅的测定介质、测定条件及干扰元素进行了探讨,拟定了简便,快速,准确测定两种水处理剂中微量铅的方法。在测定条件下,方法的线性范围为０￣５０ｎｇ·ｍｌ＾－１,检出限为０．４ｎｇ·ｍｌ＾－１,回收率在９０％￣１１０％之间。     

氢化物发生/原子吸收分光光度法测定食盐中铅

采用氢化物／原子吸收光谱法测定食盐中痕量铅，使用流动注射氢化物发生器，自动吸入试样和NaBH4溶液，空气／乙炔火焰加热石英管原子化器。对测定条件及共存元素的允许量进行了研究，采用K3[Fe(CN)6]作氧化剂。方法的灵敏度是0．28n/mL/1％吸收，检出限为0．10ng/mL，回收率在94％－102％之间，RSD为2．1％－5．3％。     

控温消解-冷原子吸收方法测定水果蔬菜中微量汞

应用程序控温－湿法消解－氢化物发生－冷原子吸收光谱法对水果蔬菜中的汞的定量方法进行了研究和探讨。对程序控温消解仪的消解条件、氢化物－冷原子吸收的测定条件进行了探讨。在本文选择的条件下，回收率为86．99％－108．00％，相对偏差为4．6％－10．8％。该方法与国家标准方法相对照，无明显差异。     

乙基磺原酸钾—MIBK萃取原子吸收测定重晶石中铅,镉

本文较详细地研究了以乙基磺原酸钾作为金属分离的溶剂萃取试剂测定重晶石中铅，镉的条件，并确定了测定方法，铅和镉与乙基磺原酸钾反应生成白色络合物，该络合物在水相溶液中能定量地萃入甲基异丁基甲酮中。它们的回收率分别为９７％－１０３％和９６％－１０１％。铅和镉分别在０－６μｇ／ｍＬ和０－０．８μｇ／ｍＬ呈线性关系。本法可测定０．０００ｘ％－０．ｘ％Ｐｂ，０．０００ｘ％－０．０ｘ％Ｃｄ．     

高盐食品中痕量铅的流动注射-氢化物发生-等离子体原子发射光谱(FI-HG-ICP-AES)在线测定

本文报道流动注射（ＦＩ）－氢化物发生（ＨＧ）与多道等离子体光谱仪联用在线测定高盐食品中痕量铅．考察了氯化钠对铅信号的影响及实验参数的选择．铅的检出限和相对标准偏差分别为１．６ｎｇ／ｍＬ和１．２％，进样频率为７５ｈ－１．方法用于两种盐制蔬菜中铅的测定，加入回收率为９７－１０１％．     

乳化剂OP存在下微分电位溶出法同时测定铅铜的研究

在乳化剂ＯＰ存在下及０．３ｍｏｌ／Ｌ ＨＣｌ介质中，铅，铜在峰电位－０．５５Ｖ及－０．３４Ｖ处分别有一灵敏的溶出峰。详细探讨了溶出分析的最佳条件。本方法已用于发酵酒，配制酒，蒸馏酒及饮料中铅，铜的直接测定，回收率为９０．６％－１１０％，ＲＳＤ为０．２％－８．２％，检出限为０．０２５－０．００５４μｇ／２０ｍＬ范围。     

氢化物发生原子荧光光谱法测定食品和饲料中的铅

应用ＡＦＳ－２２０１型双道原子荧光光谱仪进行了氢化物发生原子荧光法测定食品和饲料中铅的研究。方法中彩高氢酸做介质，并对各种最佳分析条件进行了探讨和验证。方法的检出限为０．３ｒｇ／Ｌ，线性范围为１．００～５００ｒｇ／Ｌ，回收率为８７％～９８％。用标准物质进行对照，其测定值均在给定的标准值范围之内。该方法操作简单、快速，灵敏度高，精密度和准确度好，线性范围宽，检出限低，所用试剂无毒性，豕仪器性能稳定，     

高盐食品中痕量铅的流动注射—氢化物发生—等离子体原子发射光谱…

本文报道流动注射（ＦＩ）－氢化物发生（ＨＧ）与多道等离子体光谱仪联用在线测定高盐食品中痕量铅，考察了氯化钠对铅信号的影响及实验参数的选择，铅的检出限和相对标准偏差分别为１．６ｎｇ／ｍＬ和１．２％，进样频率为７５ｈ＾－１，方法用于两种盐制蔬菜中铅的测定，加入回收率为９７－１０１％。     

氢化物发生ICP—AES法测定药用植物中的痕量锗

本文应用氢化物发生ＩＣＰ－ＡＥＳ法研究了药用植物样品中痕量锗的测定方法，系统地研究了ＩＣＰ－ＡＥＳ仪器参数及氢化物发生条件对锗谱线信背比的影响，考察了１３种共存元素的干扰，并比较了植物样品的３种前处理方法，选定Ｈ３ＰＯ４－ＨＮＯ３－Ｈ２Ｏ消化，在３ｍｏｌ／ＬＨ３ＰＯ４介质中，以１５ｇ／ＬＮａＢＨ４还原，测定药用植物样品可的锗，相对标准偏差≤２．９％，回收率为９４％～１０３％，方法检出限达０．１３μ     

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.