Phosphirenium Ions as Masked Phosphenium Catalysts: Mechanistic Evaluation and Application in Synthesis
作者:Danila Gasperini、Samuel E. Neale、Mary F. Mahon、Stuart A. Macgregor、Ruth L. Webster
DOI:10.1021/acscatal.1c01133
日期:2021.5.7
catalytic cycle. A competing off-cycle process leading to vinyl phosphine formation is detailed for the hydrosilylation of benzophenone for which an inverse order in [silane] is observed. Experimentally, the formation of side products, including off-cycle vinyl phosphine, is favored by electron-donating substituents on the phosphirenium cation, while catalytic hydrosilylation is promoted by electron-withdrawing
Nickel nanoparticles supported on graphene as catalysts for aldehyde hydrosilylation
作者:Juan F. Blandez、Iván Esteve-Adell、Ana Primo、Mercedes Alvaro、Hermenegildo García
DOI:10.1016/j.molcata.2015.11.011
日期:2016.2
Nickel nanoparticles (NPs) supported on different undoped or doped with N or B graphenes (Gs) have been tested as catalyst for the hydrosilylation of aldehydes to obtain the corresponding siloxanes with high conversion and good selectivity in short reaction time. The different Gs employed were obtained by pyrolysis under inert atmosphere of alginate or chitosan, modified or not with boric acid. Then the metal NPs obtained by polyol reduction method using ethylene glycol were adsorbed on Gs. The Ni-containing G catalysts were characterized by electron microscopy, XPS and Raman spectroscopy. The scope of the Ni/G catalyst includes aliphatic and aromatic aldehydes as well as a variety of hydrosilanes. (C) 2015 Elsevier B.V. All rights reserved.
Enhanced nucleophilic fluorination and radiofluorination of organosilanes appended with potassium-chelating leaving groups
作者:Mohammed H. Al-huniti、Shuiyu Lu、Victor W. Pike、Salvatore D. Lepore
DOI:10.1016/j.jfluchem.2013.12.005
日期:2014.2
the feasibility of enhancing the fluorination of organosilanes by appending potassium-chelating groups to the substrates. For this purpose, eight organosilanes were prepared in which a linear or cyclic leaving group, with putative potassium-chelating ability, was attached covalently to a congested silicon atom via an ether linkage to serve as a potential nucleophilic assisting leaving group (NALG).
在这里,我们旨在探索通过将钾螯合基团附加到基材上来增强有机硅烷氟化的可行性。为此,制备了八种有机硅烷,其中具有假定的钾螯合能力的线性或环状离去基团通过醚键共价连接到拥挤的硅原子上,作为潜在的亲核辅助离去基团 (NALG)。具有预期强钾螯合能力的有机硅-NALG 增强了与乙腈中氟化钾的反应,以生产有机氟硅烷,无需单独添加相转移试剂。使用回旋加速器产生的 [ 18 F] 氟离子也观察到类似的速率增强( t 1/2 = 109.7 min, β + = 97%) 在 MeCN-0.5% H 2 O 中存在碳酸钾。该研究发现金属螯合 NALG 单元可以加速空间拥挤的硅原子处的氟化和放射性氟化反应。