نتایج جستجو برای: heterocyclic phenols

تعداد نتایج: 20669  

Journal: :Chemical communications 2013
Wei Zeng Wanqing Wu Huanfeng Jiang Liangbin Huang Yadong Sun Zhengwang Chen Xianwei Li

Regioselective synthesis of polysubstituted benzofurans using a copper catalyst and molecular oxygen from phenols and alkynes in a one-pot procedure has been reported. The transformation consists of a sequential nucleophilic addition of phenols to alkynes and oxidative cyclization. A wide variety of phenols and alkynes can be used in the same manner.

2017
Yajun Liu Shasha Liu Yan Xiao

Phenols and aryl thiols are fundamental building blocks in organic synthesis and final products with interesting biological activities. Over the past decades, substantial progress has been made in transition-metal-catalyzed coupling reactions, which resulted in the emergence of new methods for the synthesis of phenols and aryl thiols. Aryl halides have been extensively studied as substrates for...

Journal: :Journal of colloid and interface science 2003
Walton J Cabrera Marcela Urzúa Hernán E Ríos

The effect of phenols containing different electron-withdrawing substituents on the potentiometric responses of several liquid PVC membranes containing the complex trioctylmethylammonium-nitrate, TOMA(+)NO(3)(-), is analyzed. The results make it possible to separate these phenols into two groups; those phenols containing electron-releasing groups, which produce almost Nernstian slopes, and thos...

Journal: :The Journal of biological chemistry 1992
Y Hsuanyu H B Dunford

A series of p- and m-substituted phenols were examined for their effect on the cyclooxygenase activity of prostaglandin H synthase in 0.1 M phosphate buffer at pH 8.0 and 25.0 +/- 0.1 degrees C. A biphasic response was observed. At low concentrations phenols stimulate, but at higher concentrations inhibit, cyclooxygenase activity. Both enhancement and inhibition are increased by phenolic substi...

Journal: :Environmental science & technology 2007
Xiuping Zhu Shaoyuan Shi Junjun Wei Fanxiu Lv Huazhang Zhao Jiangtao Kong Qi He Jinren Ni

Electrochemical oxidation of some p-substituted phenols (p-nitrophenol, p-hydroxybenzaldehyde, phenol, p-cresol, and p-methoxyphenol) with electron-donating and -withdrawing substituents was studied to reveal the relationship between the structure and the electrochemical reactivity of p-substituted phenols using a boron-doped diamond electrode by voltammetry and bulk electrolysis. Voltammetric ...

Journal: :journal of the iranian chemical research 0
yeshwant b. vibhute p.g. department of chemistry, yeshwant mahavidyalaya, nanded-431 602, india. sandeep v. khansole p.g. department of chemistry, yeshwant mahavidyalaya, nanded-431 602, india.

the kinetics of iodination of the phenol and substituted phenols using pyridiniumiodochloride in methanol has been studied under varying conditions. the rates show first orderkinetics each in pyridinium iodochloride and phenols. the rates of reactions are measured atdifferent temperature and activation parameters for all phenols computed. hammett plot is foundto be valid and the corrletion betw...

Journal: :Postepy higieny i medycyny doswiadczalnej 2013
Izabela Biskup Iwona Golonka Andrzej Gamian Zbigniew Sroka

INTRODUCTION Phenols are the most abundant compounds in nature. They are strong antioxidants. Too high level of free radicals leads to cell and tissue damage, which may cause asthma, Alzheimer disease, cancers, etc. Taking phenolics with the diet as supplements or natural medicines is important for homeostasis of the organism. MATERIALS AND METHODS The ten most popular water soluble phenols w...

Journal: :Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 2010
Huijuan Zhang Jiping Zhu Yong-Lai Feng

A rapid and sensitive method using pressure-assisted electrokinetic injection (PAEKI) as the on-line sample enrichment technique and electrospray-tandem mass spectrometry as the monitor has been developed for the determination of four halogenated phenols, 2,4,6-trichlorophenol, 2,4-dichlorophenol, 2,3,4,6-tetrachlorophenol and tetrabromobisphenol A, in water samples. In 8-min of injection, the ...

2007
J. Michałowicz W. Duda

Phenols and their derivatives commonly exist in the environment. These compounds are used as the components of dyes, polymers, drugs and other organic substances. The presence of phenols in the ecosystems is also related with production and degradation of numerous pesticides and the generation of industrial and municipal sewages. Some phenols are also formed during natural processes. These comp...

2017
Zihang Qiu Jiang-Sheng Li Chao-Jun Li

We herein describe a palladium-catalyzed formal aromaticity transfer coupling reaction between phenols and pyrrolidines or indolines to generate the corresponding N-cyclohexyl pyrroles or indoles. In this transformation, the aromaticity of phenols is formally passed on to the pyrrolidine or indoline units. Substituted phenols thus can serve as latent cyclohexyl equivalents for the fast construc...

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