نتایج جستجو برای: natural catalysts

تعداد نتایج: 513446  

2010
Shuli Yan Craig DiMaggio Siddharth Mohan Manhoe Kim Steven O. Salley K. Y. Simon Ng

Heterogeneous catalysts are promising for the transesterification reaction of vegetable oils to produce biodiesel and have been studied intensively over the last decade. Unlike the homogeneous catalysts, heterogeneous catalysts can be easily separated from reaction mixture and reused for many times. They are environmentally benign and could be easily operated in continuous processes. This revie...

Journal: :Chemical communications 2016
Shoubhik Das Felix D Bobbink Safak Bulut Mylène Soudani Paul J Dyson

The catalytic N-formylation and N-methylation of amines using CO2 as the carbon source represents a facile and sustainable approach for the synthesis of pharmaceuticals and natural products. Herein, we describe highly effective and inexpensive thiazolium carbene-based catalysts derived from vitamin B1 for the N-formylation and N-methylation of amines, using polymethylhydrosiloxane (PMHS) as a r...

2008
Brian L. Conley Somesh K. Ganesh Jason M. Gonzales Daniel H. Ess Robert J. Nielsen Vadim R. Ziatdinov Jonas Oxgaard William A. Goddard Roy A. Periana

Selective, low-temperature hydroxylation of alkanes catalyzed by transition-metal complexes is an important area of study, given its possible applications to natural-gas conversion as well as to more efficient production of bulk chemicals and energy. Several promising electrophilic catalysts that couple C–H activation to facile oxy-functionalization of the resulting electrophilically activated ...

Journal: :Bioorganic & medicinal chemistry 2014
Megan V Doble Andrew C C Ward Peter J Deuss Amanda G Jarvis Paul C J Kamer

Oxidation reactions are an important part of the synthetic organic chemist's toolkit and continued advancements have, in many cases, resulted in high yields and selectivities. This review aims to give an overview of the current state-of-the-art in oxygenation reactions using both chemical and enzymatic processes, the design principles applied to date and a possible future in the direction of hy...

2013
A. M. Elmaghraby I. A. Mousa A. A. Harb M. Y. Mahgoub

Synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives from aldehydes, 1,3-dicarbonyl derivatives and urea or thiourea using granite and quartz as new, natural and reusable catalysts. Some of the 3,4-dihydropyrimidin-2(1H)-thione derivatives were used to prepare new heterocyclic compounds. The antimicrobial activity of selected examples of the synthesized ...

Journal: :journal of nanostructures 2014
a. badiei m. azmard m. karimi p. zarabadi-poor

carbon nanotubes were synthesized over a series of zn-containing fe/alumina catalysts by chemical vapor deposition method at two reaction temperatures of 850 and 950 °c using methane as a carbon source. catalysts were synthesized by keeping fe concentration constant and varying zn concentration to study the effects of zn. the catalysts were characterized using x – ray powder diffraction and n2 ...

Journal: :international journal of nanoscience and nanotechnology 2014
s. abbasian m. taghizadeh

h-zsm-5 nano-zeolites were synthesized by hydrothermal method using tetrapropylammonium hydroxide (tpaoh) as a template in the presence of various tpabr concentrations. the effect of different tpabr/tpaoh molar ratios was studied on the catalytic performance of dehydration of methanol to dimethyl ether (dme) in a fixed bed reactor under the same operating conditions (t=300°c, p=1 atm, and whsv=...

2010
Zaiku Xie Zhicheng Liu Yangdong Wang Qihua Yang Longya Xu Weiping Ding

Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, hi...

2016
Manju Kurian S. Kavitha

In recent years, Pillared InterLayered Clays (PILCs) have been widely used in several applications; in particular in adsorption and catalysis. The research interest in this family of solids has increased considerably. Clay minerals provide distinct nanometer-scaled layers and interlayers for engineering them as active catalysts. As such, strategic design and preparation has led to a variety of ...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2011
Aram Chang Shanteri Singh Kate E Helmich Randal D Goff Craig A Bingman Jon S Thorson George N Phillips

Glycosyltransferases are useful synthetic catalysts for generating natural products with sugar moieties. Although several natural product glycosyltransferase structures have been reported, design principles of glycosyltransferase engineering for the generation of glycodiversified natural products has fallen short of its promise, partly due to a lack of understanding of the relationship between ...

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