LC-electron capture APCI-MS for the determination of nitroaromatic compounds

The determination of selected nitroaromatic compounds in liquid chromatography-mass spectrometry with electron capture (EC) ionisation using a commercial atmospheric pressure chemical ionisation (APCI) interface in the negative mode is described. The electron capture effect is observed for nitroaromatics which do not easily undergo deprotonation under these conditions. Depending on the structure of the analytes, either dissociative or, for the first time in LC-MS, non-dissociative electron capture is observed. Limits of detection and linear range for the determination of the analytes match those obtained for nitroaromatics which undergo deprotonation. The investigated substances comprise numerous substituted nitrobenzenes and nitrobenzooxadiazoles.     

Absolute configuration determination of 2-(2-oxo-3-indolyl)acetamide derivatives

We describe a reliable method for determining the absolute configuration of 2-(2-oxo-3-indolyl)acetamides based on analysis of the ¹H NMR spectra of their phenylethylamide diastereomers. The conformational preferences for two diastereomeric amides were calculated by DFT, which matched well with the experimental results. X-ray diffraction analysis allowed us to validate the method.     

Synthesis of 3-(1-hydroxyalkyl)-4,5,6,7-tetrahydroindazole derivatives. Structure determination of N-alkyl isomers

A novel series of 3-(1-hydroxyalkyl)-4,5,6,7-tetrahydroindazoles and their 1 and 2-alkyl-3-(1-hydroxyalkyl)-or-3-(1-acetoxyalkyl) derivatives were synthesized via condensation between 3-oxo-2,3,4,5,6,7-hexahydrobenzo[b]furans or 2-(2-acetoxyacyl)cyclohexanones and hydrazines. Structure assignment are based on ¹H and ¹³C nmr spectra.     

Synthesis, spectroscopic properties and crystal structure determination of 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole derivatives

Substituted 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole derivatives 2, 3 and 6 were synthesized. 2-(2-Pyridin-4-yl-vinyl)-1H-benzimidazole 2 and 6-methyl-2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole 3 were prepared by condensation reaction from 3-pyridin-4-yl-acrylic acid and corresponding 1,2-phenylenediamines in polyphosporic acid (PPA). 2,7,11-b-Triaza-benzo[c]fluorene 4 was prepared by photochemical dehydrocyclization reaction of ethanolic solution of 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole 2. 2-(2-Pyridin-4-yl-vinyl)-3H-benzimidazole-6-carbonitrile 6 was prepared by condensation reaction from 3-pyridin-4-yl-propenal and 4-cyano-1,2-phenylenediamine using p-benzoquinone as oxidants. The structure of novel benzimidazole derivatives has been studied by ¹H and ¹³C NMR, IR, MS, UV/Vis and fluorescence spectroscopy. The structure of 2-(2-pyridin-4-yl-vinyl)-1H-benzimidazole 2 was confirmed by X-ray single crystal structure analysis. The conformation of the molecule is E in regard to substituents position around vinyl double C=C bond. The non-planar molecules are mutually connected via the N–H···N and C–H···N type of intermolecular hydrogen bonds into infinite chains spreading along y axis.     

八-4-(四氢糠氧基)酞菁铕(HI)的双酞菁衍生物LB膜特性

合成了八-4-(四氢糠氧基)酞菁铕(Ⅲ)(A)、八-4-(正壬氧基)酞菁铽(Ⅲ)(B)、双酞菁铽(C)和八-4-硝基酞菁铽(D),通过元素分析、红外光谱、质谱和紫外-可见光谱加以确认.测定了配合物A的π-A曲线,表明有很好的成膜性,Z型沉积形成的石英LB膜具有很强的荧光响应,随着LB膜厚度增加,荧光强度增加.掺杂邻菲咯啉的混合LB膜荧光强度比纯膜强,但不是邻菲咯啉加入的量越多发光性越强.研究结果表明nA:nphen=1:10时有最好的荧光行为.同时研究了A和LB膜对于NH3,NOx(x=1,2)和Cl2的气敏性.当A和LB膜分别在NH3和NOx(x=1,2)为5×10-5时,未观察到响应.而Cl2气中,在2×10-6的情况下,迅速产生了响应.在低体积分数条件下(2×10-6～8×10-5),电导率随着Cl2体积分数的改变而呈直线变化.     

Formation of 1,2-0-(1-methoxycarbonyl)ethylidene derivatives of sugars from 1,2-0-(1-cyano)ethylidene derivatives and reverse transformation

Conclusion 1,2-0-(1-Methoxycarbonyl)ethylidene derivatives of sugars formed during the methanolysis of 1,2-0-(1-cyano)ethylidene derivatives can be converted into the initial cyanoethylidene derivatives. Consequently, the 1,2-0-(1-methoxycarbonyl)ethylidene function was proposed as a unique protecting group for 1, 2-0-(1-cyano)ethylidene function.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1120–1125, May, 1987.     

One-pot synthesis of 2-(dicyanomethylene)-1,2-dihydropyridine derivatives

The synthesis of 2-(dicyanomethylene)-1,2-dihydropyridine derivatives from the reactions of arylmethylidene derivatives of malononitrile dimers with 1,3-dicarbonyl compounds is described.     

Some derivatives of 4-(4-aminophenylamino)-2,2,6,6-tetramethylpiperidine

4-(4-Aminophenylamino)-2,2,6,6-tetramethylpiperidine was synthesized by alkylation of 4-aminotriacetoneamine with 4-chloronitrobenzene, followed by hydrogenation of the nitro derivative. Its reactions with acrylic, methacrylic, and itaconic acids were carried out. Transformations of the N-substituted amino acids to derivatives of 2-pyrrolidinone and dihydropyrimidinedione were studied.Kaunas Technological University, Kaunas LT-3028. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 629–631, May, 1997.     

Synthesis and oxidation of (E)-1,2-diphenyl-2-(arylimino) ethanol derivatives

The compounds (E)-1,2-diphenyl-2-(phenylimino)ethanol, (E)-1,2-diphenyl-2-(p-tolylimino)ethanol, and (E)-2-((4-chlorophenyl)imino)-1,2-diphenylethanol) were synthesized by reaction of a p-substituted aniline with benzoin then oxidized with chromium trioxide–triethylamine in chloroform to give (E)-1,2-diphenyl-2-(phenylimino)ethanone, (E)-1,2-diphenyl-2-(p-tolylimino)ethanone, and (E)-2-((4-chlorophenyl)imino)-1,2-diphenylethanone in very high yield. The products were characterized by IR and NMR spectral analysis.     

Spectrophotometric determination of zinc with 1-(2-pyridylmethylidene)-5-(salicylidene)thiocarbohydrazone

The absorbance of the yellow complex formed in pH 4.8 acetate buffer is measured at 410 nm in 40% (v/v) dimethylformamide. The molar absorptivity is 68 000 l mol^?1 cm^?1. The effect of interferences is discussed, and the method is applied to zinc in tap water and standard alloys.     

Synthesis of derivatives of 2-(o-nitrobenzyl)pyridine

Diazotization of 2-(o-nitro-p-aminobenzyl)pyridine (I) in concentrated H₂SO₄ and subsequent diazo-reaction lead to the formation of 2-(o-nitro-p-halogenbenzyl)pyridines. During the acylation reaction with acetic anhydride and benzoyl chloride, the corresponding derivatives are readily formed. Compound I reacts with benzyl chloride with the formation of the corresponding monoand dibenzyl derivatives and with p-nitrobenzaldehyde with the formation of the corresponding azomethine.     

N1-(2-furoylmethyl) and N1-(5-nitro-2- furoylmethyl) derivatives of uracil and its 5-substituted derivatives

The corresponding N₁-(2-furoylmethyl) and N₁-(5-nitro-2-furoylmethyl) derivatives of uracil and its 5-substituted derivatives were obtained by the reaction of 2-bromo- and 5-nitro-2-bromoacetylfurans with uracil, 5-fluorouracil, and thymine. The structures of these compounds as N₁-substituted uracils were proved by a study of the UV spectra at various pH values. The computational method of expanding the UV spectra into individual bands was used.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1268–1270, September, 1971.     

Spectrofluorimetric determination of iridium(IV) traces using 4-pyridone derivatives

A new spectrofluorimetric determination of iridium(IV) with 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) or 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) is reported. Iridium(IV) react with HX or HY and chelates were extracted into chloroform or dichloromethane. The organic phase showed fluorescence. The fluorescence measurements to quantify iridium were carried out in its fluorescent band centred at λ_ex=373 nm and λ_em=480 nm. Under optimal conditions, the calibration graphs were linear over the concentration range of 0.1-7.6 μg ml⁻¹ of iridium for Ir(IV)-HX and 0.1-5.8 μg ml⁻¹ for Ir(IV)-HY with a correlation coefficients of 0.999 and 0.992 and relative standard deviation of ±1.1%.The method is free from interference by Rh(III) and Pt(IV), which normally interfere with other methods. Iridium can be determined in the presence of 300-fold excess of rhodium(III) and 10-fold excess of platinum(IV).The method was applied successfully to the determination of iridium in some synthetic mixtures and mineral sample gave satisfactory results.     

Convenient synthesis of 2-(methylsulfonyl)pyrimidine derivatives

An efficient and convenient approach for the preparation of functionalized 2-(methylsulfonyl)pyrimidine derivatives has been developed through cyclic condensation of malonate derivatives with S-methylisothiouronium sulfate followed by derivation and oxidation in water–acetone mixture using oxone as the oxidant. This synthetic strategy provides an efficient and environmentally friendly approach for easy access to 2-(methylsulfonyl)pyrimidine derivatives with considerable yields.     

Intramolecular cyclization of 5-(o-carboxyphenyl)pyrrole derivatives

A new method is proposed for the synthesis of derivatives of indeno[1,2-b]-pyrrole-4-onesby intramolecular cyclization of the corresponding 5-(o-carboxyphenyl)pyrroles by trifluoroacetic anhydride.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1333–1335, October, 1987.     

Synthesis of new 2-(alkenylsulfanyl)pyrimidine derivatives

Isothiuronium salts prepared by treatment of allyl bromide, 2,3- and 1,3-dichloropropenes, and 1,3-dichlorobut-2-ene with thiourea reacted with pentane-2,4-dione and 4,4,4-trifluoro-1-(thiophen-2-yl)-butane-1,3-dione to afford new pyrimidine derivatives, 2-(alkenylsulfanyl)-4,6-dimethyl- and 2-(alkenylsulfanyl)-4-(thiophen-2-yl)-6-(trifluoromethyl)pyrimidines.     

Chemical properties ofN-(amidomethyl)- andN-(imidomethyl)glycine derivatives

N-Nitroso,N-sulfonyl, andN-acyl derivatives ofN-(amidomethyl)- andN-(imidomethyl)-glycine esters have been synthesized by the reactions of these esters with HNO₂ or with sulfonylating and acylating reagents.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1299–1305, July, 1995.     

New 4-(benzotriazol-1-yl)-1,2,3-triazole derivatives

A new 4-(benzotriazol-1-yl)-1,2,3-triazole structure was obtained by the diazotization reaction of either of 1-(2-aminophenyl)-4-carboxamido-5-amino-1H-1,2,3-triazole ( 1c ) or of the corresponding Dimroth isomer 1d . It underwent some common reactions to evaluate its chemical behaviour and structure. An analogous reaction sequence was carried out from the 2-nitro-4-methylphenyl azide, to assign the structure to the nitro derivatives prepared. The structure of the new compounds prepared was confirmed by chemical and spectroscopic methods.