4203-50-3Relevant articles and documents
Silicon diimide gel as an efficient stationary phase in thin layer chromatography for acid-sensitive organic compounds
Kitney, Stuart P.,Sajedin, Seyed M.,Rocher, Vincent,Cheng, Fei,Kelly, Stephen M.
, p. 11080 - 11082 (2017)
We report the use of mesoporous silicon diimide gel as a basic stationary phase in thin layer chromatography for the characterisation and purification of acid-sensitive compounds. The gel is prepared by a simple sol-gel process and exhibits a large specific surface area, almost monodisperse pores and basic properties due to free-hanging amine groups.
Elaborate Tuning in Ligand Makes a Big Difference in Catalytic Performance: Bulky Nickel Catalysts for (Co)polymerization of Ethylene with Promising Vinyl Polar Monomers
Zhang, Yanping,Mu, Hongliang,Wang, Xuling,Pan, Li,Li, Yuesheng
, p. 2329 - 2340 (2019/04/25)
To reveal effect of electronic or steric modification of phosphino-phenolate nickel complex for preparing optimized catalysts, we take elaborated studies on structure-performance relationship by finely modifying substituents on ortho-phenoxy position or phosphorus moiety of this catalyst. It reveals that these newly synthesized complexes are thermally robust, and exhibits very high activity (up to 107 g molNi?1 h?1) in ethylene polymerization even at 120 °C. Associated with stoichiometric experiments, experimental results prove that nickel complexes bearing electron-withdrawing substituents on ortho-phenoxy position or electron-donating substituents on phosphorus atom show higher activity than contrastive catalysts toward ethylene polymerization and ethylene–methyl acrylate (MA) copolymerization. Among these catalysts, 3 g bearing a strong electron-withdrawing substituent on ortho-phenoxy position exhibits the highest activity, and produces copolymers with the highest molecular weight and analogous MA incorporation. Various challenging polar vinyl monomers, like polyethylene glycol monomethyl ether acrylate, can be efficiently copolymerized with ethylene.
Cyclopropenium Enhanced Thiourea Catalysis
Smajlagic, Ivor,Durán, Rocio,Pilkington, Melanie,Dudding, Travis
supporting information, p. 13973 - 13980 (2018/11/21)
An integral part of modern organocatalysis is the development and application of thiourea catalysts. Here, as part of our program aimed at developing cyclopropenium catalysts, the synthesis of a thiourea-cyclopropenium organocatalyst with both cationic hydrogen-bond donor and electrostatic character is reported. The utility of the this thiourea organocatalyst is showcased in pyranylation reactions employing phenols, primary, secondary, and tertiary alcohols under operationally simple and mild reaction conditions for a broad substrate scope. The addition of benzoic acid as a co-catalyst facilitating cooperative Br?nsted acid catalysis was found to be valuable for reactions involving phenols and higher substituted alcohols. Mechanistic investigations, including kinetic and 1H NMR binding studies in conjunction with density function theory calculations, are described that collectively support a Br?nsted acid mode of catalysis.
