نتایج جستجو برای: base catalyst

تعداد نتایج: 299630  

2017
Shunsuke Kanai Ippei Nagahara Yusuke Kita Keigo Kamata Michikazu Hara

Acid-base solid catalysts synthesized with structurally controlled uniform active sites can lead to unique catalysis. In this study, a CePO4 catalyst was synthesized using a hydrothermal method and found to exhibit high catalytic performance for the chemoselective acetalization of 5-hydroxymethylfurfural with alcohols, in sharp contrast to other homogeneous and heterogeneous acid and/or base ca...

Journal: :Organic & biomolecular chemistry 2011
Thomas C Nugent Mohammad Shoaib Amna Shoaib

A three component catalyst system entailing an amino acid (O(t)Bu-L-threonine), a hydrogen bond donor (sulfamide), and an amine base (DMAP) allows α-branched aldehyde addition to nitroalkenes in good to high yield and excellent ee. Importantly, the lowest reported catalyst loading (5.0 mol%) and aldehyde stoichiometry (1.2-2.0 equiv) is demonstrated and in most instances the best current produc...

2016
Christopher J. A. Warner Andrew T. Reeder Simon Jones

Twelve P-chiral phosphine oxides were screened for their ability to act as a chiral Lewis base catalyst for the asymmetric hydrosilylation of ketimines, providing chiral amines in good conversion and yield, but relatively poor enantioselectivity (ee <30%). Mechanistic studies paralleling work on chiral sulfinamides have shown a non-linear relationship of catalyst enantioselectivity and the chir...

Journal: :Organic & biomolecular chemistry 2015
Yury N Kotovshchikov Gennadij V Latyshev Nikolay V Lukashev Irina P Beletskaya

Cu-catalyzed Pd-free Sonogashira coupling has been proposed as a straightforward and convenient route to valuable steroidal enynes. A biligand catalyst system based on Ph3P and TMEDA has been designed. The protocol was utilized for the efficient coupling of iodosteroids with diverse terminal alkynes and 1-trimethylsilylalkynes. A possible role of an auxiliary ligand as a phase-transfer catalyst...

Journal: :Chemical communications 2011
Magnus Rueping Carlos Vila René M Koenigs Konstantin Poscharny David C Fabry

A dual catalytic system combining photoredox and Lewis base catalysis has been developed. By the appropriate choice of light source and catalyst, the photoredox cycle can be optimally modulated to match the base catalyzed reaction cycle to provide the corresponding products under mild reaction conditions.

Journal: :Chemical communications 2006
H V Rasika Dias Xiaoyu Wang R M Gamini Rajapakse Ronald L Elsenbaumer

The aniline dimer, N-(4-aminophenyl)aniline has been polymerized cleanly under mild conditions to obtain an emeraldine base form of polyaniline using [MeB(3-(Mes)Pz)3]CuCl as the catalyst and H2O2 as the oxidant, while the subsequent acidification of the emeraldine base gives the conducting emeraldine salt form of polyaniline.

Journal: :Chemical communications 2011
Antonín Trojánek Jan Langmaier Jakub Šebera Stanislav Záliš Jean-Michel Barbe Hubert H Girault Zdeněk Samec

The catalytic effect of tetraphenylporphyrin on the oxygen reduction with ferrocene in 1,2-dichloroethane can be finely tuned by varying the molar ratio of the acid to the catalyst present in the solution. The mechanism involves binding of molecular oxygen to the protonated free porphyrin base, in competition with ion pairing between the protonated base and the acid anion present.

1997
Richard Bond

Explains that the Canadian federal government has recently cut $800 million in transfer payments for education to the provinces, with further cuts planned for the next two years. Consequently, there is growing concern among administrators and professional educators as to the likely impact of these developments in Ontario. Examines the impact of incremental resource reductions on an Ontario boar...

Journal: :Molecules 2014
Manuela Oliverio Paola Costanzo Anastasia Macario Giuseppina De Luca Monica Nardi Antonio Procopio

Heterogeneous bifuctional catalysts are multifunctional synthetic catalysts enabling efficient organic transformations by exploiting two opposite functionalities without mutual destruction. In this paper we report the first Er(III)-based metallorganic heterogeneous catalyst, synthesized by post-calcination MW-assisted grafting and modification of the natural aminoacid L-cysteine. The natural ac...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید