紫尿酸光度法同时测定铁和钴

利用铁、钴配阴离子在365nm处的吸光度具有良好的加和性,建立了同时测定铁、钴的紫尿酸光度法。铁,钴量均在0～50.0μg/29ml范围内符合比耳定律。方法用于自来水中铁、钴的同时测定,结果分别与邻菲罗啉光度法和亚硝基R盐光度法一致,回收率分别为96％～102％和98％～104％。     

K系数－多波长最小—乘回归分光光度法同时测定三组分的研究

将双波长Ｋ系数分光光度法和多波长线性回归分光光度法相结合，并采用最小一乘法准则计算回归系数，提出了一种同时测定三组分的新方法，即Ｋ系数－多波长最小一乘回归分光光度法。该法不需要吸收曲线交点和等吸收点，且能较好地克服异常点的影响，得到比最小二乘法更好的回归稳健性。方法用于测定模拟混合色素样品和饮料样品中的柠檬黄、胭脂红、果绿，相对误差为—３．６％～２．８％，回收率为９６．３％～１０４．８％，变异系数小于２．７９％。     

乙酰丙酮分光光度法测定水性涂料及胶粘剂中的甲醛含量

建立测定水性涂料和胶粘剂中甲醛含量的乙酰丙酮分光光度法。测定甲醛的线性范围为0．00～80.29μg，相关系数为0．9999，水性涂料和胶粘剂样品中甲醛含量测定结果的相对标准偏差分别为3．2％、2.8％，回收率分别为89％～93％、90％～96％。     

比值导数光谱与多波长最小二乘回归分光光度法同时测定苯甲酸、苯甲醛和苯甲醇

提出了比值导数光谱多波长最小二乘回归分光光度法测定苯甲酸、苯甲醛和苯甲醇三组分混合物。合成试样４ 次平行测定的相对标准偏差为０ ．１６ ％ ～４．３５ ％ 。回收率在９１ ．４３ ％ ～１０５．９ ％ 之间。     

氢化物原子荧光光谱法测定水中微量砷和硒

研究了氢化物发生-原子荧光光度法测定水中微量砷和硒的方法。结果表明,检出限:砷为0.0518μg/L,硒为0.0524μg/L;11次测定的相对标准偏差为0.36％～0.62％;标准回收率:砷为96.8％～100.9％;硒为95.9％～103.7％。方法简便、快速、灵敏,适于生活饮用水、地表水和水源水中微量砷、硒的同时测定。     

光催化降解过程中苯酚的分光光度法测定

提出了用双波长紫外分光光度法测定含对苯醌和苯酚混合液中苯酚的方法,解决了用分光光度法直接测定苯酚时对苯醌分析的干扰。选择测定波长为270和292nm。用于纳米二氧化钛光催化降解苯酚过程中苯酚的测定。标准样品的加标回收率为：99.79％～101．17％,相对标准偏差小于0．50％;样品测定的加标回收率为：99．14％～104．75％,相对标准偏差小于2．20％,苯酚的检出限为0．10mg／L。     

5-Br-PADAP直接光度法测定发锌

为建立一种简便、快速、灵敏的直接光度法测定发锌,将发样经无机化处理后,以5-Br-PADAP作为显色剂,在表面活性剂存在下直接光度法测定头发锌含量。结果表明,该法线性范围为0～612.0μmol/L,回收率为99.4％～102.4％,批内变异系数(CV)和批间变异系数分别为0.027和0.033。55例健康人头发锌含量为171.8±67.5μg(x±2s)。可见5-Br-PADAP直接光度法测定发锌具有操作简单、快速灵敏、结果可靠的优点,适合临床应用。     

多波长线性回归－导数分光光度法测定对苯二酚、邻苯二酚和苯酚

本文将导数分光光度法与多波长线性回归法联用，测定了电有机合成产品中的对苯二酚、邻苯二酚和苯酚的含量。回收率在９５．０％～１００．１％之间。模拟合成样品分析结果的相对误差为０．１％～６．６％。方法简便。     

微波消解-分光光度法快速测定农药废水中的总磷

利用微波消解技术对农药废水样品进行预处理,然后进行其中总磷的测定,消解时间从传统的高温高压消解30 min缩短到8 min.用微波消解-分光光度法和高压消解-分光光度法对两个农药废水样品进行了6次平行比对测定,测定结果经统计检验无显著性差异.微波消解法测定结果的相对标准偏差为0.483％～0.906％(n=6),加标回收率为95.5％～97.0％.该方法准确、快捷,适用于农药废水中总磷的快速测定.     

催化极谱法直接测定贵金属冶金物料中铑

用溴化亚锡光度法测定銠和铱,分析流程冗长、繁琐。应用铑在盐酸-甲醛底液中的催化波可不经分离直接测定铑,克服了光度法测铑手续繁琐之弊,且可与催化比色法测定铱相配合,达到了简化铑、铱分析流程的目的。本文拟出测定贵金属冶金原料、中间产品中0.001～0.50％铑的快速、准确方法。分析结果同光度法一致,变动系数<6％。     

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.     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.     

Copper-catalyzed multicomponent reactions of 2-iodoanilines,benzylamines, and elemental sulfur toward 2-arylbenzothiazoles

A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.