邻硝基苯基荧光酮显色计算机求解超定方程组分光光度法同时测定镧, …

研究在曲拉通Ｘ－１００存在下，镧、铈、镨、钕与邻硝基苯基荧光桐显色反应的条件，测定配合物的最大吸收波长、摩尔吸光系数及配合比，建立了用计算机求解超定的 分光光度法同时镧、铈、镨、钕的方法，编制的计算机程序用于稀土铝合金中四元素的同时测定。     

邻硝基苯基荧光酮显色计算机求解超定方程组分光光度法同时测定镧、铈、镨、钕

研究在曲拉通X-100存在下,镧、铈、镨、钕与邻硝基苯基荧光酮显色反应的条件,测定配合物的最大吸收波长、摩尔吸光系数及配合比,建立了用计算机求解超定方程组分光光度法同时测定镧、铈、镨、钕的方法,编制的计算机程序用于稀土铝合金中四元素的同时测定。     

稀土高氯酸溶液导数吸收光谱的研究及其在分析中的应用——Ⅵ.高阶导数光度法直接测定轻稀土-铝中间合金中的铈、镨和钕

本文提出了用高氯酸溶液中的高阶导数光度法直接测定稀土-铝合金中铈、镨、钕、再用差减法求镧的方法。分析结果与X-荧光光谱法结果一致。本方法具有快速、简便和准确的优点。     

水溶液中稳定四价镧系化合物的研究(Ⅰ)——在六偏磷酸钠水溶液中稳定Tb(Ⅳ)

已知镧系元素中铈、镨、钕、铽及镝可形成四价化合物^[1]。然而除铈以外,其余的四价化合物多数是用干法或由非水介质中获得的。     

简讯

荧光光度法同时测定稀土氧化物中铈、钆、铽 铈、钆、铽和其它稀土元素经常共存于从稀土矿提取的氧化物中,广东工业大学刘春英等在0.6 mol/L的盐酸介质中,分别用252 nm、273 nm、220 nm作为Ce~(3 )、Gd~(3 )、Tb~(3 )的激发波长,产生相应的最佳发射波长为350 nm、310 nm和544nm。用盐酸体系测定混合样比用硫酸体系Gd~(3 )的检测限提高1倍,Gd~(3 )对Ce~(3 )的抗干扰能力提高10倍。同时测定3     

偶氮硝羧光度法测定矿石中铈组稀土元素

本文报导了偶氮硝羧的合成方法,研究了偶氮硝羧与稀土元素的显色反应,提出了不经分离,在钇组稀土存在下直接光度法测定铈组稀土(镧、铈、镨、钕)的新方法,并采用PMBP-苯萃取分离伴生元素,用偶氮肿Ⅲ光度法测定稀土总量,用偶氮硝羧光度法测定铈组稀土分量。可以测定矿石中0.0X—X％的稀土总量及铈组稀土分量,方法简便、快速、重现性好,适用于磷钇矿、独居石和吸附型稀土矿的分析。     

荧光光度法测定稀土元素研究进展

文章综述了近20年来国内外有关稀土元素荧光光度法的研究进展.主要从测定体系、测定波长、检出限、线性范围等方面对铈、铕、钐、镝、铽、镧、钇等稀土元素进行研究.最后对一些新的荧光技术如激光诱导时间分辨光谱、时间分辨荧光免疫分析等进行了简单讨论.文章引用文献69篇.     

在水溶液中用原碲酸根阴离子稳定铽(Ⅳ)的研究

在镧系元素中,除铈以外镨和铽也可以以正四价氧化态存在这一事实早已为人们所熟知。     

《理化检验-化学分册》第42卷（2006年）总目次

试验与研究期页材料组成特性的统计表征新方法——原位统计分布分析1 1铽—依诺沙星—邻菲啰啉络合物荧光猝灭法测定ATP 1 6遗传神经网络用于分光光度法同时测定钢中镧和铈1 9新试剂SBDR固相萃取光度法测定烟草中汞1 12达旦黄与氨基糖苷类抗生素相互作用的共振瑞利散射光谱研究及其应用1 16腈菌唑分子印迹聚合物的制备及识别性能研究2 77芯片毛细管电泳快速分离检测黄素单核苷酸合成品中的核黄素2 80铁氰根和聚组氨酸复合膜修饰电极用于多巴胺的电催化测定2 83凝胶净化液相色谱法同时检测染红食品中对位红和苏丹红染料2 86柱后衍生离子色…     

某些稀土元素的薄层色谱分离和吸光光度法测定

本文研究以硅胶/淀粉/硝酸铵作固定相,用磷酸三丁酯/丁酮/乙酸乙酯/硝酸作展开剂的薄层色谱分离轻稀土元素,钇与钕元素。在硅胶/淀粉/硝酸铵为2.8/0.15/0.5,磷酸三丁酯/丁酮/乙酸乙酯/硝酸(1∶1)为24/45/13.5/2.4时、镧、铈、谱、钕、钐可以满意地分离;磷酸三丁酯/丁酮/乙酸乙酯/硝酸(1∶1)为18/45/13.5/2.4时,钇与钕比例在1∶1—100∶1时也可以满意地分离。应用偶氮氯膦Ⅲ吸光光度法测定分离后稀土元素,可用于轻稀土为主的稀土氧化物中镧、铈、镨、钕的分离及测定。应用本法分离及测定了独居石中镧、铈、镨、钕。     

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.     

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.     

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.     

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.     

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.     

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.