流动注射离子交换预浓集火焰原子吸收光谱法直接测定人尿中痕量镉

应用高效的流动注射在线离子交换预浓集火焰原子吸收光谱测定系统直接测定了人尿中痕量镉。选择２００μＬ锥形离子交换柱，内装多孔玻璃固定化的８－羟基喹啉离子交换剂，在ｐＨ９条件下样品流速为３．５ｍＬ／ｍｉｎ，４０ｓ装样，用２ｍｏｌ／ＬＨＣｌ洗脱，在分析速度为６０样／ｈ，获得３０倍的富集倍率。检出限为０．３μｇ／Ｌ。镉含量水平为４０μｇ／Ｌ的尿样，连续测定１１次的相对标准偏差为１．５％。尿标准参考物...?     

茚三酮缩7—氨基—8—羟基喹啉—5—磺酸催化荧光测定痕量钒（Ⅴ）及其…

合成了新型席夫碱类试剂茚三酮缩７－氨基－８－羟基喹啉－５－磺酸，建立了该剂催化荧光测定痕量钒的 新体系，反应在盐酸体系中进行，其λｅｘ／λｅｍ为３２５／４４８（ｎｍ），钒（Ⅴ）的量在０－４０．０μｇ／Ｌ、４０．０－１６０．０μｇ／Ｌ呈良好线性关系，检测下限为１．７μｇ／Ｌ，方法用于水样痕量钒的测定，结果令人 满意。     

痕量铅的在线SHA离子交换预浓度流动注射原子吸收测定

采用羟基磷灰石微型柱的流动注射系统与火焰原子吸收光谱联结对工业废水中铅进行预浓集测定。在进样时，被分析物沉积在羟基磷灰石微型柱上，并通过注射半胱氨酸（碱性条件下）予以洗脱。该方法成功地应用于工业废水的分析。通过回收实验，标准物质分析等方法评价了准确度。４ｍｌ样品体积的检测限：为４μｇ／Ｌ（４ｍＬ／ｍｉｎ），进样时间１ｍｉｎ，２μｇ／ｍＬ和０．２μｇ／ｍＬ含量测定的相对标准偏差分别为１．５％和２．２     

过碘酸钾氧化鸡冠花红动力学光度法测定食品中痕量碘

基于硫酸介质中，草酸钠作活化剂，碘催化过碘酸钾氧化鸡冠花红而使其褪色的反应，建立了测定痕量碘的新方法。方法灵敏、简便、选择性好。测定碘的线性范围为０－２０μｇ／Ｌ；检出限为０．６６μｇ／Ｌ。用于食品中痕量碘的测定，结果满意。     

固氮蓝藻分离富集石墨炉原子吸收光谱法测定痕量Cr（Ⅵ）／Cr（Ⅲ）

本文选取固氮蓝藻分离富集Ｃｒ（Ⅵ）／Ｃｒ（Ⅲ），用墨炉原子吸收光谱法测定。结果表明该方法对１０ｍＬ试样，测定Ｃｒ（Ⅵ）的检测限为０．１μｇ．Ｌ＾－１＇变异系数为３．２％，在０－４５μｇ．Ｌ＾－１范围内线性关系好；测定Ｃｒ（Ⅲ）的检测限为０．３μｇ．Ｌ＾－１、变异系数３．７％，在０－４０μｇ．Ｌ＾－１范围内线性关系好。方法选择性高、富集率高。测定矿泉水、海水及自来水中的铬，获得满意结果。     

钒（Ⅳ）—硫胺素荧光光度法的研究与应用

利用钒（Ⅳ）作为氧化剂将硫胺素氧化成硫胺荧,建立了一种测量痕量硫胺素的荧光分光光度法,并将该方法应用于药物中硫胺素的测定。该方法测定硫胺素的线性范围为０．８～２４０．０μｇ／Ｌ;检出限为０．４５μｇ／Ｌ;对于４０．０μｇ／Ｌ的硫胺素测定１０次,其相对标准偏差为１．５％。     

流动注射在线液—液萃取原子吸收光谱法测定生物样品中的铅

本文利用所设计的一种新型流动注射液－液萃取重力分相器，建立了流动注射液溶剂萃取原子吸收光谱法测定铅的新方法，详细地研究了流动注射在线萃取的实验条件及流路系统，方法的精密度和检出限分别为２．５％（ｎ＝１１）和２．８μｇ／Ｌ（ｋ＝３）。用拟定的方法测定了峰蛹，粮食等生物样品中的铅，结果与参考值相吻合。     

反相流动注射催化光度法测定痕量锰

本文基于在邻菲罗啉活化下，锰（Ⅱ）对高碘酸钾氧化罗丹明Ｂ褪色的催化作用，建立了痕量锰的反相流动注射分析方法。方法的线性范围为０－５０μｇ／Ｌ，检测下限为０．７μｇ／Ｌ锰（Ⅱ）。对２０μｇ／Ｌ锰（Ⅱ）测定九次的相对标准偏差为１．８％，进样频率不少于６０次／ｈ。方法应用于水样和标准镁合金样品分析，结果满意。     

流动注射在线萃取-火焰原子吸收法测定化探样品中痕量铊

１引言原子吸收光谱法是测定生物、地质和环境样品中铊的重要方法，但多以电热原子吸收光谱法为主。常规的火焰原子吸收光谱法由于测定灵敏度低则往往难以满足分析要求。溶剂萃取预处理直接进行原子吸收光谱测定痕量元素，可起到分离富集的作用并能提高灵敏度和选择性，而流动注射在线萃取技术与原子吸收光谱法相结合却更具有简便、安全、不污染环境等优点。本文研究了在线萃取流程中各项最佳参数，用盐酸－甲基异丁基酮（ＭＩＢＫ）将铂萃取到有机相后，将有机相直接注入火焰中进行原子吸收测定。本法检出限为５μｇ／Ｌ；相对标准偏差为１…     

亚甲紫分光光度法测定微量亚硝酸根

研究了在盐酸介质中微量亚硝酸根与亚甲紫发生的重氮化反应,建立了测定微量亚硝酸根的新方法。方法的线性范围为８－４４０μｇ／Ｌ ＮＯ＾－２,检出限为８μｇ／Ｌ ＮＯ＾－２方法已用于水中微量亚硝酸根的测定,并对反应机理了初步讨论。     

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.