نتایج جستجو برای: phase transfer catalyst

تعداد نتایج: 909786  

Soheil Sayyahi Somayeh Shagholi

In this study, a one-pot and efficient method is reported for the synthesis of symmetrical disulfides from alkyl halides in the present of sulfur and 1-butyl-3-methylimidazolium hydroxide as a basic reagent and phase transfer catalyst. The reaction proceeded very fast and afforded the desired products in moderate to excellent isolated yields.  

Journal: :Chemical communications 2011
Seiji Shirakawa Kun Liu Hironobu Ito Keiji Maruoka

Efficient catalytic asymmetric synthesis of 1,1-disubstituted tetrahydro-β-carbolines has been achieved via asymmetric alkylation of 1-cyanotetrahydro-β-carbolines using a binaphthyl-modified N-spiro-type chiral phase-transfer catalyst. This is a valuable example of hitherto difficult highly enantioselective alkylations at α-carbon of the cyano group under phase-transfer conditions.

Journal: :Molecules 2010
Antonio Monopoli Angelo Nacci Vincenzo Calò Francesco Ciminale Pietro Cotugno Annarosa Mangone Lorena Carla Giannossa Pietro Azzone Nicola Cioffi

Palladium nanoparticles have been electrochemically supported on zirconium oxide nanostructured powders and all the nanomaterials have been characterized by several analytical techniques. The Pd/ZrO(2) nanocatalyst is demonstrated to be a very efficient catalyst in Heck, Ullmann, and Suzuki reactions of aryl halides in water. The catalyst efficiency is attributed to the stabilization of Pd nano...

Journal: :Angewandte Chemie 2012
Steven Bloom Cody Ross Pitts David Curtin Miller Nathan Haselton Maxwell Gargiulo Holl Ellen Urheim Thomas Lectka

A group effort: Reported is the title reaction using a polycomponent catalytic system involving commercially available Selectfluor, a putative radical precursor N-hydroxyphthalimide, an anionic phase-transfer catalyst (KB(C(6)F(5))(4)), and a copper(I) bis(imine). The catalyst system formed leads to monofluorinated compounds selectively (see example) without the necessity for an excess of the a...

Journal: :Chemical communications 2013
Wenchao Chen Wenguo Yang Lin Yan Choon-Hong Tan Zhiyong Jiang

Highly enantioselective phase-transfer alkylation of 3-substituted-2-oxindoles with activated bromomethanes is disclosed with a broad substrate scope by using bicyclic guanidinium as a catalyst and a Lewis acid as the co-catalyst. The alkylation adducts are versatile intermediates to accomplish the syntheses of pyrroloindolines and furoindolines.

Journal: :Chemical communications 2012
Zhijun Tai Junying Zhang Aiqin Wang Mingyuan Zheng Tao Zhang

A temperature-controlled phase-transfer catalyst-tungsten acid, which in combination with a robust heterogeneous catalyst Ru/C shows a high activity and exceptional reusability for the one-pot conversion of cellulose to ethylene glycol. This binary system can be reused more than 20 times with ethylene glycol yield over 50%.

Journal: :Angewandte Chemie 2017
Xin Yan Heyong Cheng Richard N Zare

Many important chemical transformations occur in two-phase reactions, which are widely used in chemical, pharmaceutical, and polymer manufacturing. We present an efficient method for performing two-phase reactions in microdroplets sheared by sheath gas without using a phase-transfer catalyst. This avoids disadvantages such as thermal instability, high cost, and, especially, the need to separate...

Journal: :Chemical Engineering Research and Design 2016

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