Melamine trisulfonic acid-catalyzed N-formylation of amines under solvent-free conditions

A highly convenient method for N-formylation of amines via treatment by formic acid in the presence of melamine trisulfonic acid as a catalyst has been developed. This method showed improvements over previous reports in terms of yield, reaction time and chemoselectivity.     

Poly(4-vinylpyridine) catalyzed hydrolysis of methyl bromide to methanol and dimethyl ether

The hydrolysis of methyl bromide with neutral water is performed in the presence and absence of various amines in a batch reactor at different temperatures (50–125 °C). Screening of poly(4-vinylpyridine) as a potential reusable solid amine catalyst showed maximum efficiency. This significant enhancement in efficiency is due to the capture of HBr by solid PVP and remains phase-separated driving the reaction forward. The major advantage of this process is that the polymer can be easily regenerated and reused without loss of activity making it a very effective catalyst for the conversion of methyl halides to methanol and dimethyl ether.     

Discrimination between ω-amino acids with chromogenic acyclic tripodal receptors functionalized with stilbazolium dyes

A tripodal receptor functionalized with a stilbazolium dye derivative has been designed, synthesized and has been used for the colorimetric discrimination between certain ω-amino acids in mixed DMSO-water 90:10 v/v solutions.     

Schiff碱N,N’-双水杨醛缩-1,6-己二胺的光致变色光谱研究

用稳态和时间相关荧光光谱、紫外 -可见吸收光谱和傅立叶变换红外光谱等方法研究了 Schiff碱N ,N -双水杨醛缩 -1 ,6-己二胺 ( BSH)的光致变色行为 .确定了光致变色的产物为双质子转移的酮式结构 .     

线性自治NDDE与CDDE解空间为有限维的充要条件

本文把文［２］中关于 Ｒ Ｄ Ｄ Ｅ 解空间为有限维的结果完整地推广到 Ｎ Ｄ Ｄ Ｅ 和 Ｃ Ｄ Ｄ Ｅ 上去，给出了相应的充要条件     

Determination of sub‐ppb epichlorohydrin levels in water by on‐line solid‐phase extraction liquid chromatography/tandem mass spectrometry

A new sensitive and selective method based on on‐line solid‐phase extraction (SPE) coupled to liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) using a triple quadrupole mass spectrometer has been developed for the determination of epichlorohydrin (ECH) in different types of water samples. ECH is not easily determined directly by ESI‐MS as it is not readily ionized, and it has a low molecular mass and high polarity. Thus, prior derivatization of ECH was necessary, employing 3,5‐difluorobenzylamine as a derivatizing agent with Fe(III) as a catalyst. In order to achieve accurate quantification, correcting for matrix effects, losses in the derivatization process and instrumental deviations, isotope labelled ECH (ECH‐d₅) was added as an internal standard (IS) to the water samples. The method was validated based on European SANCO guidelines using drinking and other types of treated water spiked at two concentration levels (0.1 and 1.0 µg/L), the lower level having been established as the limit of quantification (LOQ) of the method. Satisfactory accuracy (recoveries between 70 and 103%), precision (RSD <20%) and linearity (from 0.05 to 50 µg/L, r >0.99) were obtained. The limit of detection (LOD) was set up at 0.03 µg/L. The method was applied to different water samples (drinking water and water samples collected from a municipal treatment water plant). In order to enhance confidence, five selected reaction monitoring (SRM) transitions were acquired, thus obtaining a simultaneous reliable quantification and identification of ECH in water, even at sub‐ppb levels. Copyright © 2009 John Wiley & Sons, Ltd.