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31.
32.
L. Bengoechea T. Hernández C. Quesada B. Bartolomé I. Estrella C. Gómez-Cordovés 《Chromatographia》1995,41(1-2):94-98
Summary The present paper describes the development of a method for the differentiation of hydroxycinnamic acid derivatives by HPLC with photodiode-array detection. Furthermore spectral data of the compounds under investigation are given. Whereas p-coumaric acid derivatives are distinguishable from caffeic and ferulic acid derivatives by the positions of their spectrum maxima and their convexity interval value, it is not possible to distinguish between caffeic and ferulic acid derivatives because of overlapping spectrum maxima and convexity interval values. 相似文献
33.
The synthesis of a biotinated amphiphile assembled from d-(+)-biotin, ethylene diamine as spacer, galactaric acid and 1-dodecylamine was achieved in six steps. The key step was the synthesis of a bisacetonide protected galactaric ester, the structure of which was determined by X-ray analysis. Aminolysis, spacer attachment, coupling with biotin and deprotection led to the amphiphilic galactaramide. 相似文献
34.
Ping He 《Journal of fluorine chemistry》2005,126(5):825-830
The reactions of fluoroalkanesulfonyl azides 1 with different indole derivatives have been studied in detail. Treatment of 1 with equimolar amount of 1,3-dimethylindole 3 in 1,4-dioxane at room temperature afforded 2-(1,3-dimethyl-1,3-dihydro-indolinylidene) fluoroalkanesulfonylimines 5 in moderate to good yields. However, under the same reaction conditions, in the case of 1 with 1,2-dimethylindole 4, the corresponding 2-fluoroalkanesulfonyl (1,2-dimethyl-1H-indol-3-yl)-amide 6 was obtained in moderate yields. In addition, the reactions of 1 and indole 7 gave different products under different conditions. Possible mechanisms of these reactions were proposed. 相似文献
35.
Summary A sensitive precolumn fluorescence derivatization method for low level detection of the, volatile (N-nitrosodimethylamine and N-nitrosopyrrolidine) and non-volatile N-nitrosamines (N-nitrosoproline and N-nitrosodiethanolamine) an high-performance liquid chromatography was developed. This method is based on the denitrosation of the compounds of interest by a mixture of hydrobromic acid and acetic acid to produce the corresponding secondary amines. These are, then, able to react with, a quinolizinocoumarin derivative (luminarin 9®) to form highly fluorescent labelled N-nitrosamine derivatives. The structural elucidation of the luminarin 9® derivatives of N-nitrosoproline and N-nitrosodimethylamine by way of example, were established by liquid chromatography-mass spectrometry (LC-MS) and by direct chemical ionization-mass spectrometry (CI-MS). The separation, derivatization and detection conditioins were optimized for all the studied compounds. The detection limits (signal to noise ratio=3) were between 0.4 and 1.0 pmol injected depending on the compound. The calibration graphs were linear for derivatized amounts in the range of 0.5–40 nmol for N-nitrosodimethylamine and N-nitrosopyrrolidine, 0.4–2- nmol for N-nitrosoproline and 1.0–40 nmol for N-nitrosodiethanolamine. The repeatability (RSD less than 3.5%, n=6) and reproducibility (RSD less than 4.8%, n-6) were satisfactory. 相似文献
36.
S. V. Kurbatova E. E. Finkelshtein E. A. Kolosova A. V. Kartashev S. N. Yashkin 《Journal of Structural Chemistry》2004,45(1):144-150
The potential of the structural analogy method in the topological studies of adamantane derivatives and analogs is demonstrated. The topological and structural characteristics of these compounds are calculated. Chromatographic retention indices were determined experimentally. Correlations between the topological indices and the physicochemical and chromatographic characteristics are investigated. 相似文献
37.
38.
Successive alkylation of 5-(3-phenylthioureido)-3H-imidazole-4-carboxamides with alkyl halides and chloroacetone gave (N-oxopropylimidazolyl)isothioureas, which were easily converted into derivatives of purine and imidazopyrazinone. In the case of ethyl 5-(3-phenylthioureido)-3H-imidazole-4-carboxylate, primary alkylation occurs at the N atom of the imidazole ring. Reactions of 5-(3-phenylthioureido)-3H-imidazole-4-carboxamides with haloketones afforded a number of 4-hydroxy-2-imidazolyliminothiazolidines and 2-imidazolylimino-Δ4-thiazolines.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2196–2204, October, 2004. 相似文献
39.
Qiang Li Pingfan Wu Yongge Wei Hongyou Guo 《Journal of organometallic chemistry》2006,691(6):1223-1228
An organic-inorganic hybrid compound, (Bu4N)2[Mo6O18(NAr)] (Ar = p-BrC6H4) has been synthesized via the DCC dehydrating protocol of the reaction of [α-Mo8O26]4− with 4-bromoaniline hydrochloride in anhydrous acetonitrile, which has been characterized by UV-Vis spectra, 1H NMR and single crystal X-ray diffraction study. By comparing the UV-Vis spectra, which were used to monitor the reaction, the optimum preparative condition for this compound was also determined. This compound crystallizes in the monoclinic space group P21/n, which is featured in a terminal para-bromophenylimido group linked to an Mo atom of a hexamolybdate cluster by a Mo-N triply bond. In addition, there are π-π dimerization of the neighboring cluster anions though the parallel aromatic rings in their crystals. 相似文献
40.