نتایج جستجو برای: solvent selectivity

تعداد نتایج: 99687  

Journal: :Chemistry: A European Journal 2021

Chemodivergent cross-couplings are those in which either one of two (or more) potentially reactive functional groups can be made to react based on choice conditions. In particular, this review focuses involving different (pseudo)halides that compete for the role electrophilic coupling partner. The discussion is primarily organized by pairs electrophiles including chloride vs. triflate, bromide ...

Journal: :Molecules 2016
David Georgiev Bartholomeus W H Saes Heather J Johnston Sarah K Boys Alan Healy Alison N Hulme

The mono ortho-bromination of phenolic building blocks by NBS has been achieved in short reaction times (15-20 min) using ACS-grade methanol as a solvent. The reactions can be conducted on phenol, naphthol and biphenol substrates, giving yields of >86% on gram scale. Excellent selectivity for the desired mono ortho-brominated products is achieved in the presence of 10 mol % para-TsOH, and the r...

Journal: :Organic letters 2006
Petra Feiertag Martin Albert Ulrike Nettekoven Felix Spindler

A homogeneous catalyst system for the asymmetric cis-hydrogenation of 2,5-disubstituted furans leading to 2',3'-dideoxynucleoside analogues is described. Best enantioselectivities (ee values of up to 72%) were obtained with cationic rhodium complexes ligated by diphospholanes of the butiphane family. The selectivity of the hydrogenation was reversed by the addition of a base or a polar protic s...

Journal: :Sustainability 2023

In this work, we present the catalytic application of naturally occurring zeolite, clinoptilolite, in oxidation α-pinene, a natural terpene compound. Clinoptilolites with different average particle sizes, designated as (in μm) clin_1 (20), clin_2 (50), clin_3 (200), and clin_4 (500–1000), were used green catalysts solvent-free α-pinene oxygen. Prior to their tests, characterized by following me...

Journal: :Journal of Chromatography A 2021

Plant extraction has existed for a long time and is still of interest. Due to technological improvements, it now possible obtain extracts with higher yields. While global yield major parameter because assesses the performance, can be interest focus on particular compounds (specific metabolites) enrich sample avoid unwanted ones, instance primary metabolites (carbohydrates, triacylglycerols). Th...

2005
SATU OJALA Riitta L. Keiski Leonid Kustov

This thesis describes efforts made on the development of an existing catalytic incinerator. The development work, called process characterization, consists of four general parts. These are the development of measurement methodology, the studying of construction materials, the selection of suitable catalysts and the testing of the effects of process operation conditions. The two application area...

Journal: :Angewandte Chemie 2014
Jie Wu Xiaoqing Yang Zhi He Xianwen Mao T Alan Hatton Timothy F Jamison

We describe an efficient continuous flow synthesis of ketones from CO2 and organolithium or Grignard reagents that exhibits significant advantages over conventional batch conditions in suppressing undesired symmetric ketone and tertiary alcohol byproducts. We observed an unprecedented solvent-dependence of the organolithium reactivity, the key factor in governing selectivity during the flow pro...

2011
Naoki HIRAYAMA

In the solvent extraction of metal cations into ionic liquids, use of Brønsted acid-type chelate extractants has some advantages including simplicity in controlling extraction selectivity by selecting suitable aqueous phase pH values and simple back-extraction recovery of the extracted metals using acid solutions. In this review, various fundamental and applied research on metal extraction usin...

Journal: :Journal of Zhejiang University. Science 2004
Yue-Zhong Wen Zhao-Hua Fang Wei-Ping Liu

Environmental concerns have highlighted the need of cleaner technologies. A cleaner, convenient and selective technology has been developed for the preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol (DPMP) from 2-methyl-benzene-1,3-diol in water as solvent. The isolated yield of DPMP is up to 86% in good selectivity. The product structure was characterized by conventional method...

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