Quantitative Determination of Silicon in Organosilicon Compounds Using Low-Temperature RF-Discharge Oxygen Plasma

Abstract

The paper describes a technique for quantitative determination of silicon in organic monomer and polymer materials based on low-temperature decomposition of samples in rf-discharge oxygen plasmas. The final step of analysis involves gravimetric determination of silicon in the form of silicon dioxide. The presence of fluorine (up to 50%) does not interfere with the determination of silicon.     

A Sensitive Spectrophotometric Method for the Determination of Some Imidazoline Derivatives by 2,6-Dichlorophenol-Indophenol

Abstract

A new and highly sensitive method is presented for the spectrophotometric determination of four imidazoline derivatives: antazoline hydrochloride, tolazoline hydrochloride, xylometazoline hydrochloride and naphazoline nitrate. The method is based on the reaction of the corresponding drug base with 2,6 - dichlorophenol -indophenol (DGPIP) in chloroform to give a blue chromogen exhibiting a maximum at 588 - 603nm. The method could be applied for the quantitative determination of the above drugs either pure or in their pharmaceutical preparations (tablets and nasal drops). The results obtained are accurate and have good reproducibility.     

Zinc-catalyzed benzylic C-H bond oxidation

A zinc-catalyzed oxidation of benzylic substrates has been developed. The corresponding carbonyl containing compounds have been produced in moderate to excellent yields. Both arenes and heteroarenes can be applied as substrates by using H₂O₂ as the oxidant.     

Liquid Chromatograph Detector for Trace Analysis of Non-Volatile N-Nitroso Compounds

Abstract

A Thermal Energy Analyzer has been interfaced to a high performance liquid chromatograph. The hplc-TEA system can be used for analysis of nanogram amounts of N-nitroso compounds.     

An Efficient Four‐component Synthesis of Spiro[indoline‐pyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyrimidine]triones

A four‐component reaction in the presence of Alum [KAl(SO₄)₂·12H₂O] as an inexpensive and reusable catalyst using the ionic liquid as an effective green reaction media is reported.     

Co-crystallizing coordination compounds

Crystallization of an equimolar mixture of 1,10-dimethylphenanthroline (DMP) and manganese(II) chloride from N,N-dimethylformamide (DMF) has been studied. Rather than a useful route to a well-defined product, it was found that identical solutions could deposit crystals of three different compounds. The most common outcome was the formation of crystals of [MnCl₂(dmp)(dmf)], 1, or co-crystallization of [MnCl₂(dmp)(dmf)] and [{MnCl₂(dmp)}₂]. The co-crystals, 2, were always found to dissolve as crystals of 1 started to grow. Crystals of a third compound, [MnCl₂(dmp)₂], 3, were also isolated once.     

Biological evaluation of novel selenazole‐based compounds as potential thioredoxin reductase inhibitors

Recently, thioredoxin reductase as a target for treatment of tumors has attracted the attention of scientists. 1,2‐[Bis(1,2‐benzisoselenazolone‐3(2 H)‐ketone)]ethane (ethaselen, BBSKE, PCT: CN02/00412), designed and synthesized previously, is an effective thioredoxin reductase inhibitor; presently it is in phase II clinical trials, targeting gastric cancer, lung cancer and colon cancer. To seek more novel and effective anticancer drugs, we have developed many selenazole‐based compounds. Evaluation of the thioredoxin reductase inhibitory effect and investigation of the mechanism of anticancer drugs require abundant thioredoxin reductase, but since commercial thioredoxin reductase is expensive its use is often limited. Therefore, the preparation of thioredoxin reductase is necessary. Base on the above investigation, in this work we have prepared thioredoxin reductase and evaluated selenazole‐based compounds, and found that 44 compounds have high inhibitory effect on thioredoxin reductase with IC₅₀ < 10 µ m , of which 16 compounds have IC₅₀ values below 1 µ m . This is helpful in investigating and elucidating the mechanism of this kind of compound. Copyright © 2012 John Wiley & Sons, Ltd.     

某些含氮有机物光催化氧化产生的自由基中间体

本文用自旋捕捉技术与ESR相结合的方法研究了某些含氮有机物TiO₂光催化降解的过程中形成的活泼中间体.选择的化合物中有丁胺、戊胺、庚胺、六氢吡啶、吡啶、2-甲基吡啶、2,6-二甲基吡啶,这些分子中的氮原子分别作为初级脂肪胺、饱和环中的二级胺以及芳环中的三级胺出现,实验中观察到N-中心自由基及C-中心自由基与自旋捕捉剂加合物的ESR信号,表明这些自由基参与这些化合物光降解的初始过程,对深入了解其光降机理是有意义的.