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光度分析中协同系数补偿方法的研究——三次标准加入法同时测定钼,… 总被引:4,自引:2,他引:2
本在两次标准加入法的基础上,提出了三组份同时测定的三次标准加入法,并应用于钼、钨和钛和流动注射同时测定。测定条件:〔水杨基荧光酮(SAF)=1.25×10^-4mol/L,〔溴化十六烷基三甲基铵(CTMAB)=2.5×10^-3mol/L,pH1.35,25℃,采样、进样时间分别为10s和18s进样频率128次/h,为消除组份间协同作用引起的吸光度加合性的偏离,定义了三组份协同系数。将其引入三组 相似文献
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协同系数补偿—动力学两次标准加入法测定相互干扰的双组份 总被引:3,自引:2,他引:3
本提出了协同铲应补偿的动力两次标准加入法,讨论了相互干扰双组份同时测定的原理,研究了钙(Ⅵ)和钨(Ⅵ)催化的H2O2-I^-动力学反应,确定了同时测定条件:[H2O2]=9.×10^-3mol/L,[I^-]=1.0×10mol/L,PH3.0,25℃;为补偿钼和钨之间的协同催化效化效应,引入了协同催化系数的概念,有效地消除了吸江度对加和性的偏离。用本法同时测定样品中的钼和钨含量,回收率分别为9 相似文献
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本文报道了磷酸三丁酯萃取-火焰原子吸收法间接测定植物及煤灰样品中痕量锗的新方法。锗与钼酸铵在0.3mol/L的硝酸介质中形成稳定的锗钼杂多酸,被磷酸三丁酯萃取,有机相直接进样测定钼而间接测定锗;特征浓度为21.8ng/mL/1%吸光度,RSD(n=11)为4.6%,加标回收率为97.6%~101.2%。 相似文献
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小波变换-偏最小二乘法用于钨、钼、钛的分光光度法同时测定 总被引:13,自引:0,他引:13
1引言小波分析方法是一种新发展起来的数学方法。本文采用小波分析光谱实验数据进行预处理,然后用偏最小二乘法(PLS)进行校正,完成了钨、钼、钛的同时测定。2实验部分2.1主要仪器与试剂日立557双波长分光光度计;奔腾586微机。W(Ⅵ)标准溶液10mg/L;Mo(Ⅵ)标准溶液2mg/L;Ti(Ⅳ)标准溶液2mg/L;水杨基荧光酮(SAF)1.0×10-3mol/L;溴化十六烷基三甲铵(CTMAB)5×10-3mol/L。2.2实验步骤(1)取一定量的W、Mo、Ti标准溶液于25mL比色管中,依次加入2mL5mol/LHCl,2,5mLSAF溶液,4.0mL(::FNIn,然看… 相似文献
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利用钨、锆-水杨基荧光酮-溴化十六烷基三甲铵络合物形成酸度的差异连续测定钨和锆 总被引:1,自引:0,他引:1
1引言研究了钨和储与水杨基荧光酮及漠化十六烷基三甲按形成三元胶束络合物时的酸度差异,发现在较低酸度(0.10~0.30mol/LHCI)时,二者均可形成稳定的三元胶束络合物,而在较高酸度(0.96~1.20mol/LHCI)时,则只有钨能形成三元络合物,铝对其无影响。本文依据这种酸度的差异,在较高酸度时测定钨,而在较低酸度时测定铝和错以差减法求得钻含量。2实验团分2.工仪器及试剂722型分光光度计。723型分光光度计。钨标准溶液:且00mg/L,储标准溶液:10‘0mg/L。水杨基荧光酮(SM)乙醇溶液:1.0Xic’mol/L。漠化十六烷基三… 相似文献
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用高铁容量法测定钨钛合金中钛时,必须先于性介质中将钛与钨分离,此法操作比较烦琐、费时。本文着重研究了对消除主体钨干扰的适宜条件,提出在1.6mol/L及0.6mol/L硫-磷酸介质中,以给定的的磷酸络合钨,应用过氧化氢差示光度法,可不经分离直接测定钛的含量。试验表明,按所取的磷酸量至少能掩蔽90mg钨,且不抑制钛显色,络合物也相当稳定,放置24h吸光度不变。在显色液中可允许0.2mg钒(Ⅴ)、0.5mg铌(Ⅴ)、5mg钼(Ⅵ)、10mg铁(Ⅲ)存在均不影 相似文献
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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%. 相似文献
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Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
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. 相似文献
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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. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
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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%). 相似文献
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Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
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. 相似文献