光谱电化学法测定水果中抗坏血酸的研究

本文采用平行入射式光谱电化学装置，对水果中的抗坏血酸进行测定并寻找了最佳的测定条件。方法简便快捷，可消除背景干扰。线性范围１．０×１０＾－５－１．０×１０＾－４ｍｏｌ／Ｌ，检测下降为４．０×１０＾－６ｍｏｌ／Ｌ，回收率高，结果满意。     

高锰酸钾—抗坏血酸化学发光体系测定抗坏血酸

本文研究了高锰酸钾－抗坏血酸化学发光体系，建立了测定抗坏血酸的化学发光分析新方法，线性响应的浓度范围为５．０×１０＾－７ｍｏｌ／Ｌ～４．０×１０＾－５ｍｏｌ／Ｌ，检出限为３．０×１０＾－７ｍｏｌ／Ｌ，对２．５×１０＾－６ｍｏｌ／Ｌ抗坏血酸进行１０次平行测定，相对标准偏差为１．６％，考察了２２种物质的干扰情况。用于维生素Ｃ片剂及注射液中抗坏血酸含量测定，结果令人满意。     

头孢噻肟钠的降解及其产物伏安行为的研究

头孢噻肟钠在ＮａＯＨ溶液中降解后，于０．１ｍｏｌ／ＬＮａＯＨ中得一灵敏的吸附伏安原峰，Ｅｐ＝－０．７８Ｖ（νｓＡｇ／ＡｇＣｌ），ｉｐ与头孢噻肟钠浓度在１．０×１０＾－＾９－１．０×１０＾－＾８，１．０×１０＾－＾８－１．０×１０＾－＾７，１．０×１０＾－＾７－１．０×１０＾－＾６ｍｏｌ／Ｌ范围内呈线性关系，检出限为５．０×１０＾－＾１＾０ｍｏｌ／Ｌ。用多种电化学手段研究其降解产物的伏安行为，测定了     

铕—敌鼠—DL—组氨酸—十六烷基三甲基溴化铵荧光体系及其应用

研究了铕－敌鼠－ＤＬ－组氨酸－ＣＴＭＡＢ荧光体系的荧光特性，测定了体系的影响因素和测定敌鼠的实验方法，体系的激发和发射波长分别为３３０ｎｍ和６１２ｎｍ，各组分的最佳浓度分别为１．０×１０＾－５ｍｏｌ／Ｌ，ＤＬ－组氨酸，１．０×１０＾－４ｍｏｌ／Ｌ，ＣＴＭＡＢ１．０×１０＾－５ｍｏｌ／Ｌ，ｐＨ为９．０，在此条件下，敌鼠浓度在６．０×１０＾－７～９．０×１０＾－５ｍｏｌ／Ｌ范围内同体系的荧光强度成线性     

溶出伏安法测定水中痕量钴

在０．０１ｍｏｌ／ＬＮＨ．Ｈ２Ｏ－ＮＨ４Ｃｌ和３．０×１０＾－５ｍｏｌ／Ｌ安息香缩氨基硫脲体系中，钴产生一灵敏的还原波，其峰电位是－０．９４Ｖ（ｖｓ．ＳＣＥ），峰电流与钴的浓度在２．０×１０－８－１．０×１０＾－６ｍｏｌ／Ｌ范围内成直线关系，检测限为５．０×１０＾－９ｍｏｌ／Ｌ，该法测定水中痕量钴结果令人满意。     

乳酸环丙沙星单扫描示波极谱法研究

研究了乳酸环丙沙星的极谱伏安行为，在ｐＨ＝８．３的０．０２ｍｏｌ／Ｌ，ＮＨ４Ｃｌ－ＮＨ３．Ｈ２Ｏ底液中，乳酸环丙沙星能产生１个灵敏的还原峰，峰电位为－１．６１Ｖ，其导数峰高与浓度在３．９×１０＾－８～１．８×１０＾－６ｍｏｌ／Ｌ和１．８×１０＾６～１．１×１０＾－５ｍｏｌ／Ｌ范围内呈现良好的线性关系，相关系数ｒ＝０．９９９７，检测下限为２．５×１０＾－８ｍｏｌ／Ｌ，用于乳酸环丙沙星注射液的测定，相     

一种基于形成杂多核络合物的荧光增敏效应的研究：Ⅲ.锰（Ⅱ）,钴（…

本研究了Ｍｎ＾２＋和Ｃｏ＾２＋对７－（８－羟基－３，６－二磺基萘偶氮）－８－羟基喹啉－５－磺酸－硼砂反应体系的混合荧光增敏作用。实验条件下，荧光增敏强度满足线性加和关系的范围是：Ｍｎ＾２＋浓度０￣２．９×１０＾－７ｍｏｌ／Ｌ；Ｃｏ＾２＋浓度０￣８．８～１０＾－７ｍｏｌ／Ｌ；总浓度不超过１．０×１０＾－６ｍｏｌ／Ｌ。检出限量为Ｍｎ＾２＋４．５×１０＾－９ｍｏｌ／Ｌ和Ｃｏ＾２＋１．４×１０＾－８ｍｏ     

冠醚存在下稀土络合物荧光体系的荧光增强效应

本详细研究了冠醚对Ｅｕ－ＴＴＡ荧光体系的增敏作用和稀土离子Ｄｙ＾３＾＋或Ｈｏ＾３＾＋对Ｅｕ－ＴＴＡ－冠醚体系的荧光强增效应。对Ｅｕ－ＴＴＡ－冠醚和Ｅｕ－Ｄｙ（或Ｈｏ）－ＴＴＡ－冠醚体系，Ｅｕ的浓度分别在１．０×１０＾－＾８－４．０×１０＾－＾６ｍｏｌ／Ｌ，１．０×１０＾－＾９－１．０×１０＾－＾７ｍｏｌ／Ｌ和１．０×１０＾－＾８－９．０×１０＾－＾６ｍｏｌ／Ｌ范围内与体系的荧光强度呈线性关系，检     

铝—酸性铬蓝K荧光光度法测定微量铝的研究

研究了酸性铬蓝Ｋ（ＡＣＢＫ）荧光光度法测定微量铝的反应。Ａｌ＾３＋与ＡＣＢＫ形成络合物的荧光强度与铝的含量在１×１０＾－８～８×１０＾－６ｍｏｌ／Ｌ范围内呈现良好的线性关系，检测限为４．８×１０＾－９ｍｏｌ／Ｌ，对４×１０＾－８ｍｏｌ／Ｌ铝重复１１次检测其相对标准偏差为４．８％，成功地用于人发及钢样中铝含量的测定。     

3.5次微分循环示波计时电位法测定铋的研究

本文将３。５次微分循环示波计时电位法应用于铋的示波特性的研究和合成样品中微量铋的测定。铋在０．１ｍｏｌ／Ｌ ＮａＯＨ支持电解质中，于示波图阴极支上产生一灵敏切口，灵敏度为２×１０＾－７ｍｏｌ／Ｌ，线性范围为４×１０＾－７－２×１０＾－６ｍｏｌ／Ｌ。     

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.     

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%).     

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.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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 substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.