流动注射化学发光法测定中药材中没食子酸

建立快速简便的流动注射化学发光分析法,用于中药材中没食子酸含量的测定.利用酸性介质中Fe3+-H2O2体系生成羟基自由基氧化没食子酸产生微弱的化学发光,用罗丹明6G来增敏化学发光.研究了影响化学发光的各种因素,探讨了可能的机理.结果表明,0.18 mol/L HCl,0.04 mol/L FeCl3,1.0 mol/L H2O2与1.0×10-4 mol/L罗丹明6G溶液组成最优的化学发光体系,没食子酸浓度在1.0×10-5～1.0×10-2 g/L和0.01～1.0 g/L范围内与化学发光强度呈很好的线性关系,r分别为0.9984和0.9947,检出限为3.0×10-6 g/L.对1.0×10-4 g/L没食子酸平行测定11次的相对标准偏差为3.8%.利用本方法成功地测定了中药材诃子和没食子中的没食子酸含量.     

流动注射化学发光法测定废水中Mn(Ⅱ)

鲁米诺与K2S2O8在碱性介质中能产生稳定的化学发光信号,Mn2+对鲁米诺过硫酸钾体系的化学发光产生微弱的抑制作用,而Ag+能增强Mn2+对发光体系的抑制作用,据此建立测定了废水中微量Mn2+的流动注射化学发光分析方法。Mn2+的浓度在1.0×10-10～1.0×10-7mol/L范围内与相对发光强度(ΔI)呈良好的线性关系,检出限为1.0×10-12mol/L;对1.0×10-7mol/LMn2+进行11次平行测定,其相对标准偏差RSD为1.3%。方法已用于测定废水中Mn2+的含量。     

离子色谱分离-亚铁氰化钾-钙黄绿素偶合化学发光测定NO_2~-

利用NO2-在酸性介质中氧化亚铁氰化钾为铁氰化钾,然后在碱性条件下和钙黄绿素化学发光反应相偶合,结合离子色谱分离和流动注射技术间接测定了NO2-。结果发现当钙黄绿素浓度为1.0×10-4mol/L,亚铁氰化钾浓度为2.0×10-4mol/L时,NO2-在1.0×10-5～1.0×10-7g/L范围内,化学发光强度与NO2-浓度成良好的线性关系(R=0.9958),检出限(3σ)为5.1×10-8g/L,对质量浓度为1.0×10-6g/LNO2-溶液进行11次平行测定,相对标准偏差为1.4%。将该方法用于蒸馏水和自来水中NO2-的测定,加标回收率分别为94.2%和107.1%。     

鲁米诺-焦性没食子酸体系抑制化学发光法测定5-磺基水杨酸

基于碱性介质中5-磺基水杨酸对鲁米诺-焦性没食子酸体系化学发光的抑制作用,建立了流动注射化学发光测定5-磺基水杨酸的新方法.在最佳实验条件下,测定5-磺基水杨酸的线性范围为1.0×10-7～1.0×10-5mol/L,相关系数为0.9996(n=5),检出限为6.8×10-8mol/,L(n=11),对1.0×10-6...     

四磺基锰酞菁作为过氧化物模拟酶在过氧化氢化学发光测定中的应用

以四磺基锰酞菁 (MnTSPc)作为过氧化物模拟酶催化H2 O2 与鲁米诺的化学发光反应 ,建立了测定环境样品中H2 O2 的化学发光分析新方法。该法的线性范围为 4 .0× 10 - 8～ 2 .0× 10 - 5mol L ;检出限为 6 .8×10 - 9mol L ;对 1.0× 10 - 6 mol L的H2 O2 进行连续 10次平行测定 ,相对标准偏差为 2 .4 %。用本法对天然雨水进行了分析测定 ,结果良好。     

Ru(bipy)2+3-CO2-3-SO2-3-KClO3体系化学发光法测定空气中的二氧化硫

提出了Ru(bipy) 2+ 3-CO 2- 3-SO 2- 3-KClO 3体系化学发光法测定溶液中亚硫酸盐的方法.SO 2- 3浓度与化学发光强度在1.0×10-7～1.0×10-4 mol/L 范围内成正比,检出限为8.76×10-8 mol/L,对1.0×10-4 mol/L SO2-3溶液6次测定的相对标准偏差为2.9%.该法用三乙醇胺作为吸收液,成功地用于测定空气中二氧化硫的含量,结果满意.     

流动注射-化学发光法测定亚甲蓝

鲁米诺在碱性条件下,可以被高锰酸钾氧化产生化学发光,亚甲蓝能显著增强该化学发光。基于这点,结合流动注射技术建立了测定亚甲蓝的化学发光新方法。在优化的实验条件下,测定亚甲蓝的线性范围为1.0×10-7~5.0×10-5mol/L,检出限为3.9×10-8mol/L,对1.0×10-5mol/L亚甲蓝进行9次平行测定,其相对标准偏差为1.0%。方法已用于注射液中亚甲蓝的测定。     

硫化镉量子点增敏化学发光体系测定痕量苯酚的研究

在碱性条件下,硫化镉量子点对鲁米诺-H2O2化学发光体系具有显著的增敏作用,而苯酚对该体系的化学发光有强烈抑制作用,以此建立了流动注射化学发光检测苯酚的新方法.在优化实验条件下,苯酚浓度在5.0×10-9 ～5.0×10-7g/L(r=0.9935)和5.0×10-6 ～1.0×10-3g/L(r=0.9982)范围内...     

双[2,4,6-三氯苯基]草酸酯-过氧化氢体系流动注射化学发光法检测地沟油中的胆固醇

基于胆固醇和冰乙酸的反应物与硫酸铁铵生成的紫色化合物能有效抑制双[2,4,6-三氯苯基]草酸酯(Bis(2,4,6-trichlorophenyl)oxalate,TCPO)-H2O2-咪唑化学发光反应,建立了流动注射-化学发光联用检测胆固醇的方法。对流动注射、化学发光等实验参数进行了优化。当咪唑浓度为0.001 mol/L,H2O2浓度为0.3 mol/L,TCPO浓度为1.0×10"3mol/L,主副蠕动泵转数分别为20和15 r/min时,体系具有最强的化学发光。在优化的实验条件下,测定胆固醇的线性范围为8.6×10"6～2.2×10"4mol/L;检出限(S/N=3)为2.5×10"6mol/L;相对标准偏差(RSD,n=11,c=6.5×10"5mol/L)为1.5%。不同加标水平下的加标回收率为95.0%～105.0%;相对标准偏差(n=6)小于3.6%。本方法已应用于地沟油中胆固醇的测定,结果令人满意。     

毛细管固定过氧化物酶流动注射化学发光法测定过氧化氢的研究

利用固定有辣根过氧化物酶的毛细管柱作为反应器与流通池,建立了一种简单、快速检测过氧化氢的流动注射化学发光分析新方法.当鲁米诺和过氧化氢的混合溶液流经反应器时,辣根过氧化物酶催化过氧化氢氧化鲁米诺产生化学发光.在选定的实验条件下,化学发光信号与过氧化氢的浓度在3.0×10-8～1.0×10-4mol/L范围内分段呈线性关系,检出限为1×10-8mol/L(S/N=3),相对标准偏差1.4%(1.0 μmol/L,n=9).该方法用于雨水中过氧化氢的测定,结果满意.     

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.