催化光度法测定痕量铁的研究──Fe（Ⅲ）－对乙酰基偶氮胂－H＿2O＿2体系

本文基于在弱酸性介质中及活化剂α，　α－联吡啶存在下，痕量铁（Ⅲ）对过氧化氢氧化对乙酰基偶氮胂的反应有强烈的催化作用，建立了催化光度法测定痕量铁的新方法。该法灵敏度为１；１４×１０￣（－１１）ｇ／ｍＬ，测定范围为０～０．１０μｇ　Ｆｅ￣３＋／２５ｍＬ，表观活化能为８２．２４ＫＪ／ｍｏｌ。应用于大米、小米和小麦中痕量铁的测定，结果满意。     

催化褪色光度法测定牡蛎中痕量铁

采用催化褪色光度法测定牡蛎中痕量铁，以获得牡蛎生长过程中富集重金属的信息。Ｆｅ（Ⅲ）在硫酸介质中能催化过氧化氢氧化甲基红的反应，并研究了影响褪色反应速度的最佳条件，方法的灵敏度为６×１０－１１ｇ／ｍＬ，测定范围为０～０．０４８μｇ／ｍＬＦｅ（Ⅲ）。方法简便，有较高的选择性。     

催化荧光法测定痕量铁的研究

本利用Ｆｅ（Ⅲ）与四乙撑五胺协同催化过氧化氢氧化还原型二氯荧光素的反应，提出了测定痕量Ｆｅ（Ⅲ）的新催化荧光方法。方法的线性范围为０．０１－０．３０μｇ／２５ｍｌ，检出限为１．３×１０＾－＾１＾０ｇ／ｍｌ，常见离子不干扰测定。用于人发，指甲，血清和面粉中痕量铁的测定，回收率为９７％－１０４％。     

铁(Ⅲ)-高碘酸钾-过氧化氢-变色酸2R催化动力学光度法测定痕量铁的研究

研究了测定铁的一种新指示反应，在稀硫酸介质中，痕量铁（Ⅲ）对高碘酸钾与过氧化氢协同氧化变色酸２Ｒ的褪色反应具有强烈催化作用，其反应的动力学条件，表观活化能Ｅ′＝１８９．８１ｋＪ／ｍｏｌ，表观反应速率常数Ｋ＝５．６７×１０－４／ｓ，半衰期ｔ１／２＝２０．３７ｍｉｎ。反应温度为９０℃，试验表明ｌｇＡ０／Ａ与Ｆｅ（Ⅲ）的浓度在３０～１００ｎｇ／２５ｍＬ范围内符合Ｂｅｒ定律，建立了催化动力学光度法测定痕量铁的新方法。方法的检测限为１．２５×１０－９ｇ／Ｌ，加入回收率在９７．０％～１０２％，应用于测定西洋参口服液、美国花旗参茶和天然矿泉水中铁的含量结果满意。     

铁（Ⅲ）—高碘酸钾—过氧化氢—变色酸2R催化动力学光度法测定痕量铁…

研究了测定铁的一种新指示反应，在稀硫酸介质中，痕量铁（Ⅲ）对高碘酸钾与过氧化氢协同氧化变色酸２Ｒ的褪色反应具有强烈催化作用，其反应动力学条件，表观活化能Ｅ′＝１８９．８１ｋＪ／ｍｏｌ表观反应速率常数Ｋ＝５．６７×１０＾－４／ｓ半衰期ｔ１／２＝２０．３７ｍｉｎ，反应温度为９０℃，试验表明１ｇＡ０／Ａ与Ｆｅ（Ⅲ）的浓度在３０～１００ｎｇ／２５ｍＬ，范围内符合Ｂｅｅｒ定律，建立了催化动力学光度法测定痕量     

烟草中Fe,Co一阶导数分光光度法同时测定的研究

本文研究了在ｐＨ４．０时，ｍｅｓｏ－四（４－磺酸基苯基）卟啉与铁、钴同时络合显色的反应条件以及一阶导数光谱行为。此体系一阶导数的灵敏度比零阶导数灵敏度高。Ｆｅ￣（３＋）～０．１８μｇ／ｍＬ、Ｃｏ￣（２＋）０～０．２４μｇ／ｍｌ，范围内符合比耳定律；检测限为：Ｆｅ￣（３＋）＝０．４８ｎｇ／ｍＬ，Ｃｏ￣（２＋）＝０．２ｎｇ／ｍＬ。回收率为：Ｆｅ９８．５％～１００．８％，Ｃｏ９９．２％～１０１．３％。此方法用于烟草中痕量Ｆｅ、Ｃｏ测定，与ＡＡＳ值相比较，结果令人满意。     

催化褪色光度法测定痕量铁的研究

研究了在ｐＨ４．５的弱酸性介质中，利用邻菲罗啉活化过氧化氢氧化紫脲酸铵褪色的指示反应，建立了催化动力学光度法测定痕量铁的新方法，方法的检出限为６．５×１０＾－７ｇ／Ｌ线性范围为０～１．０μｇ／２５ｍＬ，用于水，粮食中痕量铁的测定，结果满意。     

新体系Fe（Ⅲ）—KIO4—偶氮氯膦Ⅲ催化动力学光度法测定食品痕量铁的…

研究了在硫酸介质中，痕量Ｆｅ（Ⅲ）催化高碘酸钾氧化氮氯膦Ⅲ的褪色反应及其动力学条件。本法检测限为８．７８×１０＾－９ｇ／Ｌ，测Ｆｅ（Ⅲ）范围０－１．４μｇ／１０ｍＬ，采用巯基葡聚糖凝胶分离富集，使本法选择性大大提高，建立了一种高灵敏、高选择测定痕量Ｆｅ（Ⅲ）的新方法，用于食品中痕量Ｆｅ（Ⅲ）的测定，结果满意。     

新体系Fe（Ⅲ）－KIO＿4－偶氮氯磷Ⅲ催化动力学光度法测定食品中痕量铁的研究

研究了在硫酸介质中，痕量Ｆｅ（Ⅲ）催化高碘酸钾氧化氨氯磷Ⅲ的褪色反应及其动力学条件。本法检测限为８．７８×１０￣（０９）ｇ／Ｌ，测Ｆｅ（Ⅲ）范围０～１．４μｇ／１０ｍＬ，采用硫基葡聚糖凝胶分离富集，使本法选择性大大提高，建立了一种高灵敏、高选择性测定痕量Ｆｅ（Ⅲ）的新方法，用于食品中痕量Ｆｅ（Ⅲ）的测定，结果满意。     

催化动力学法测定痕量硒（Ⅳ）

１引言利用催化动力学光度法测定痕量硒已有报道，但都存在Ｆｅ３＋等一些共存离子干扰等问题。作者通过实验观察到，在盐酸介质中，Ｓｅ（Ⅳ）能强烈催化氯酸钾氧化甲苯胺兰褪色反应，据此建立了催化动力学光度法测定痕量硒的一种新方法。方法具有体系简单稳定，选择性好等特点，检出限为８４ｘ１０－７ｇ／Ｌ，线性范围为０～９×１０－７ｇ／２５ｍＬ。直接用于水；人发、面粉和牛奶等食品样中的痕量硒（Ⅳ）测定，结果较好。２实验方法在两支相同的２５ｍＬ比色管中，一支加入０．５μｇ的标准硒（Ⅳ）工作溶液，另一支不加。然后依次分…     

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%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.     

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.