A Prolific Catalyst for Selective Conversion of Neat Glycerol to Lactic Acid
作者:Zhiyao Lu、Ivan Demianets、Rasha Hamze、Nicholas J. Terrile、Travis J. Williams
DOI:10.1021/acscatal.5b02732
日期:2016.3.4
We report the synthesis and reactivity of a very robust iridium catalyst for glycerol to lactate conversion. The high reactivity and selectivity of this catalyst enable a sequence for the conversion of biodiesel waste stream to lactide monomers for the preparation of poly(lacticacid). Furthermore, experimental data collected with this system provide a general understanding of its reactive mechanism
Cuprophilic interactions can greatly enhance the radiative rate constants via either exceptionally fast phosphorescence or TADF, and thus present a design motif for highly efficient CuI-based emitters.
Tunable iridium catalyst designs with bidentate N-heterocyclic carbene ligands for SABRE hyperpolarization of sterically hindered substrates
作者:Pierce Pham、Christian Hilty
DOI:10.1039/d0cc06840c
日期:——
A series of bidentate N-heterocycliccarbene (NHC) iridium catalysts, [Ir(κC,N-NHC)H2L2]BPh4, are proposed for SABRE hyperpolarization. The steric and electronic properties of the NHCs are used to tune substrate affinity and thereby SABRE efficiency. The sterically hindered substrates 2,4-diaminopyrimidine and trimethoprim yielded maximum proton NMR signal enhancements of ∼300-fold and ∼150-fold, respectively
提出了一系列双齿N-杂环卡宾(NHC)铱催化剂[Ir(κC,N-NHC)H 2 L 2 ] BPh 4,用于SABER超极化。NHC的空间和电子性质用于调整底物亲和力,从而调整SABRE效率。位阻的底物2,4-二氨基嘧啶和甲氧苄啶产生的最大质子NMR信号增强分别为约300倍和约150倍。
Simplified Preparation of Copper(I) NHCs Using Aqueous Ammonia
The use of aqueous ammonia as a coordinating and basic reagent for the metalation of imidazol(in)ium salts derived from (S)IPr and (S)IMes with simple inorganic copper precursors is reported. The synthesis of copper carbene complexes was performed using aqueous/alcoholic media in mild conditions (room temperature to 60 °C) with short reaction times. Heteroleptic bromide and iodide complexes could be
报道了使用氨水作为配位和碱性试剂,用于将(S)IPr和(S)IMes衍生的咪唑(in)盐与简单的无机铜前体金属化。卡宾铜配合物的合成是在温和的条件下(室温至60°C),反应时间短,使用水/醇介质进行的。可以高效地制备(S)IPr的异杀菌溴化物和碘化物配合物,而SIMes和(S)IPr则易于获得氯化物配合物。氨还允许通过变体方法在乙醇中高效合成均相的[Cu(NHC)2 ](Y)(NHC =(S)IMes; Y = PF 6,BF 4)。
Cationic Gold Catalysis with Pyridine-Tethered Au(III) NHC-Carbenes: An Experimental and DFT Computational Study
作者:Mikko Muuronen、Jesus E. Perea-Buceta、Martin Nieger、Michael Patzschke、Juho Helaja
DOI:10.1021/om3003027
日期:2012.6.11
A novel strategy is developed to produce catalytically active cationic Au(III) species by pyridine-tethered NHC complexes. The catalytic properties of two NHC complexes, equipped with distinct pyridine moieties, were studied for two catalytic benchmark reactions, the cycloisomerization of alkynylfurans to isobenzofuranoles and o-alkynylanilines to indoles. Optimal catalytic results were obtained employing a complex tethered with an electron-rich, p-methoxy-substituted pyridine. The catalysis showed high selectivity, yielding clean product conversions, while the catalytic TONs achieved in the studied reactions are well comparable with the ones reported in the literature for silver salt-activated Au(I) NHC carbene catalysts. Computational results at the DFT level support the hypothesis that equilibrating ionic complexes are the plausible catalytically active species. Computational inspection of the energetics and molecular orbital involved in the reaction reveals that the ionic state is more favored in the AuCl3NHC complex equipped with the electron-rich pyridine.