碲(Ⅳ)-碘化钾-罗丹明B体系荧光猝灭反应测定痕量碲

在高浓度碘化钾溶液中，碲（Ⅳ）与Ｉ－形成［ＴｅＩ８］４－配阴离子，［ＴｅＩ８］４－再与罗丹明Ｂ 形成离子缔合络合物［ＲｈＢ］４［ＴｅＩ８］，使罗丹明Ｂ溶液的荧光明显猝灭。反应适宜介质为０．６０ ～１．００ ｍｏｌ／Ｌ的磷酸溶液；线性范围为 ０～１６μｇ／Ｌ碲；反应有高灵敏度，对于碲的检测限为 ０·９１ μｇ／Ｌ，方法也有较好选择性，可用于某些样品中碲的测定。     

含碲唑杂环部花青的合成

含碲唑杂环部花青的合成罗学红，刘秀芳，徐汉生（武汉大学化学系，４３００７２）部花青（又称份菁，ｍｅｒｏｃｙａｎｉｎｅｓ）是一类重要的功能染料。它不仅可以作为感蓝或感绿的光谱增感剂应用于照相化学领域￣［１］，也可作为光盘染料用于其它信息记录￣［２］。这...     

标准样品修正-X射线荧光光谱法测定碲铋矿石中碲和铋的含量

作为重要的"三稀"矿产资源,碲在半导体制冷、特种合金、薄膜太阳能电池等领域有着不可替代的作用[1],四川石棉大水沟碲铋硫铁矿是迄今为止有报道的唯一碲原生独立矿床[2]。然而,由于此类矿床的稀缺性,相关分析方法研究尚少[2-3],当前对岩矿、化工样品中高含量碲的测定或采用重量法(YS/T 1227.1-2018《粗碲化学分析方法第1部分:碲量的测定重量法》)或酸溶后稀释测定,铋则采用容量法(GB/T 15926-2010《铋矿石化学分析方法铋量测定》),前处理方法难以统一,影响分析效率。     

沉淀分离ICP-AES法测定高纯阴极铜中铅铋碲

研究了用虱氧化铁共沉淀分离富集高纯阴极铜中铅、铋和碲的最佳条件与ICP-AES法的最佳工作条件。在选定的最佳条件下测铅、铋和碲的检出限分别为0．0034,0．013和0．0077μg·ml-1,回收率分别为97．8%-100．8%、95．5%-106．5%和98．5-100．5%。测定高纯阴极铜中铅、铋和碲,结果满意。     

碲铋矿中碲铋分离方法的研究及应用

本文对富碲铋矿中碲铋的分离条件进行了详细研究。在ｐＨ８～１２范围内，当Ｆｅ＞１０ｍｇ时，Ｔｅ、Ｂｉ与Ｆｅ共沉淀完全而与其它杂质元素分离，沉淀用１０％ＫＯＨ溶解Ｔｅ而与Ｂｉ、Ｆｅ分离，溶液经酸化后用Ｋ２Ｃｒ２Ｏ７法滴定Ｔｅ。平行测定１０次碲铋矿粉和矿渣，ＲＳＤ为１．０７％。     

Nafion修饰金电极阳极溶出伏安法测定痕量碲

本文用Ｎａｆｉｏｎ修饰金盘电极，在０．０４ｍｏｌ／ＬＬｉＣｌ和ＰＨ２的Ｈ２ＳＯ４底液中，阳极溶出伏安法测定痕量碲，研究了富集溶出过程的特性和优化条件，碲浓度在０．２－１５ｎｇ／ｍＬ范围内与溶出峰电流呈良好的线性关系。本法灵敏度高，选择性好，用于测定小麦粉和玉米粉中痕量碲，测定标准偏差小于０．０７μｇ／ｇ，与ＩＣＰ测定结果比较其相对误差小于１６％。     

C60、C70与丙酮离子体系的气相反应及量化研究

1990年Kratschmer［1，2］等人实现了C60和C70的宏观量制备后，有关fullerene的化学研究迅速展开［3－5］．业已发现C60具有极为丰富的化学性质．在对C60化学性质的认识过程中，气相离子化学一直起着重要的作用［6］．Roth等人［7］在ICR质谱仪中，制得了C60外部键合金属的衍生物C60M＋；Caldwell及合作者［8］在质谱仪上，利用高动能的C60与轻气体（He，Ne，H2，D2）碰撞，得到了笼内包含轻气体原子的C60；Bohme［9，10］等人在流动后辉光质谱仪上，系统地研究了C60的单、双、三电荷离子与多种有机物的反应，获得了相应的C60加合…     

纳米SnO2的制备

ＳｎＯ２在陶瓷、气敏半导体材料及催化剂等方面被广泛应用［１］．纳米级的ＳｎＯ２因具有明显的表面效应而受到关注，其制备方法也受到重视［２］．纳米ＳｎＯ２的制备方法较多，有沉淀法［２］、水热法［３，４］、溶胶－凝胶法［５］、火焰合成法［６］等．然而要制备...     

碘催化吲哚衍生物与二芳基二碲醚芳碲化反应制备3-芳碲基吲哚

在20 mol%K_2S_2O_8存在下, 20 mol%I_2催化吲哚衍生物与二芳基二碲醚反应,高产率获得一系列3-芳碲基吲哚化合物.该反应对不同吲哚衍生物和二芳基二碲醚均具有较好的适用性.此外,该方法具有反应条件温和、产率高、原子经济性等优点,为3-芳碲基吲哚化合物的制备提供高效的路径.     

粮食及人发中微量碲的催化极谱测定

碲为毒性元素,人体含碲量过高时将会导致肾、肝、心脏等多种疾病。而碲及其化合物又为冶金、电子等工业所广泛应用。为此,微量、超微量碲的分析方法近年来相继出现,各有其特点。本文介绍碲铼催化波用于粮食作物与人发中微量碲的测定,此法具有灵敏度极高、重现性好、简便、快速和准确度好等特点。     

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.