人工神经网络法同时测定苯二酚异构体

研究了人工神经网络法与紫外分光光度分析相结合，用于邻苯二酚、间苯二酚、对苯二酚异构体的含量测定。本研究采用人工神经网络法，直接对苯二酚异构体混合液的紫外吸收光谱数据进行预测，不需预先分离，即可得到各异构体的浓度。     

催化光度法测定茶叶中的痕量锰

1引言催化光度法测定痕量锰已有不少报道,溴酚蓝是一种酸碱指示剂,变色范围为3．0－4．6,酸式呈黄色,碱式呈蓝紫色。以邻啡罗啉作活化剂,高碘酸钾氧化溴酚蓝为指示反应测定痕量锰已有报道,其空白反应速度随温度升高迅速加快,影响了测定的灵敏度。我们在实验中发现,使用氨三乙酸作活化剂,空白反应速度受温度影响很小,测定锰的灵敏度和选择性都有较大改善,从而拟定了催化光度测定痕量锰的新方法,并已用于茶叶中锰的测定。2实验部分2．1仪器和试剂754型紫外可见分光光度计（上海第三分析仪器厂）。113801型超级恒温器（辽阳恒温仪…     

同步荧光光谱法测定十二烷基苯磺酸钠的临界胶束浓度

采用表面张力、电导率、紫外可见吸收光谱、恒波长同步荧光光谱法分析了典型阴离子表面活性剂十二烷基苯磺酸钠在水溶液中的临界胶束浓度（CMC）。 结果表明,同步荧光光谱法测定CMC时的样品用量少,检测灵敏度高,具有较高的准确性;测定的十二烷基苯磺酸钠的第一临界胶束浓度和第二临界胶束浓度分别为1.48和6.90 mmol/L,与传统的表面张力法和电导率法的测定结果一致。 验证了同步荧光光谱法测定表面活性剂CMC的可靠性。     

高效液相色谱法同时测定异α-酸与四氢异α-酸

1引言啤酒花深加工产品异α-酸与四氢异α-酸近年来已被全国各大啤酒厂广泛使用，但并无统一检测手段。文献报道的方法用乙腈和水作为流动相，单独测定四氢异α-酸。乙腈价格较高，用此方法进行产品质量控制成本高，本法采用甲醇代替乙腈，大大降低成本。分离效果好，并可同时测定异α-酸与四氢异α-酸。2实验部分2．1仪器与试剂P200Ⅱ型高压恒流泵，UV200Ⅱ型紫外可变波长检测器（大连伊力特科学仪器有限公司）。HepersilBDSC185μm柱（150×4.6mmi．d．）。甲醇，85％磷酸，四丁基羟胺10％水溶液，均为分析纯。水为双蒸水。2．2色谱条…     

紫外分光光度法测定酒葡萄原汁中的维生素C

还原型维生素Ｃ在紫外区 2 4 3 8ｎｍ处有最大吸收峰 ,而且在较大范围内具有良好的线性关系 ,因此可用紫外分光光度法测定。但由于酒葡萄原汁有很深的颜色 ,含有大量在紫外区也有吸收的其它成份 (主要是葡萄糖和多种有机酸 ) ,影响测定结果的准确性 ,因此 ,必须对样品紫外区本底吸收进行校正。谭延华[1 ] 提出一种以Ｃｕ2 +作氧化剂 ,对样品中紫外干扰物质 ,进行本底校正的方法 ,但由于使用了 2 4 3 8ｎｍ处有紫外吸收的ＥＤＴＡ对体系中的剩余Ｃｕ2 +进行掩蔽 ,严重影响了测定结果的准确性。为此 ,李军[2 ] 对紫外分光光度法测定食品中还原…     

聚苯胺纳米纤维的共溶剂界面聚合及储能性能研究

本文采用以盐酸溶液为水相、四氯化碳为有机相的界面聚合法,通过向水相中分别引入具有非对称结构的甲醇和乙醇,以及具有对称结构的异丙醇和丙三醇作为共溶剂,成功制备出聚苯胺纳米纤维.采用场发射扫描电镜、紫外可见光谱和傅里叶红外光谱对其形貌和结构进行了表征分析,并通过循环伏安测试、恒流充放电测试和交流阻抗测试着重研究了不同共溶剂...     

肌苷和肌苷酸测定的新方法研究

采用紫外吸光光度法与高压纸电泳法联用，对次黄嘌呤类物质-肌苷及肌苷酸含量测定，试验了高压纸电泳法分离肌苷及肌苷酸的最佳条件，并对肌苷口服液等样品进行分离和测定。     

司帕沙星衍生化反应及其紫外光谱性质研究

研究了碘与喹诺酮类药物司帕沙星反应产物的紫外光谱性质。发现，在酸性介质中司帕沙星极易被亚硝酸氧化，其氧化产物被碘取代后可产生强的紫外吸收光谱，其紫外吸收较司帕沙星强67倍，据此建立了衍生化增敏紫外光谱测定司帕沙星的新方法。该方法可用于片剂中司帕沙星含量的测定，结果令人满意。     

动力学—两次标准加入法同时测定钼和钨

本文提出了动力学－两次标准加入法双组份同时测定的新方法，讨论了测定的基本原理；用停流ＦＩＡ光度法研究了钼和钨共同催化的Ｈ２Ｏ２－Ｉ＾－动力学反应体系，并建立了钼和钨同时测定的条件，用本法测定了钢样和模拟样品中的钼、钨含量，结果满意，钼和钨的回收率分别为９７％－１０２．６％和９８．２％－１０３％；相对标准偏差分别为２．８％－３．２％和２．１％－３．５％。     

人工神经网络在仪器分析实验数据处理中的应用

以紫外分光光度法为例,将人工神经网络方法引入到仪器分析实验数据处理中,实现了吗啉的紫外分光光度法测定并拓宽了仪器分析的应用。     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.