1855-09-0Relevant articles and documents
Methyltrioxorhenium catalysed epoxidations: A comparative study of different N-donor ligands
Altmann, Philipp,Kühn, Fritz E.
, p. 4032 - 4035 (2009)
This report presents a comparative study on the influence of various N-donor ligands coordinated to methyltrioxorhenium (MTO) on the catalytic activity of olefin epoxidation. A monodentate (4-tert-butylpyridine), a bidentate (4,4′-dimethyl-2,2′-bipyridine) and a Schiff-base ligand were chosen for the coordination to MTO. This report is supposed to act as a benchmark for past and future results in this type of catalysis. Until now, unfortunately, the results are often difficult to compare due to varying sets of reaction conditions. In the present examination, identical reaction conditions were applied to find the optimum in performance. Accordingly, (i) ligand concentration, (ii) reaction temperature, (iii) catalyst concentration, (iv) olefin and (v) the solvent were varied. For labile olefins such as trans-β-methylstyrene, both the monodentate and the bidentate pyridine derivates show very good selectivities and activities with a MTO/ligand ratio of 1:5 at 25 °C. The Schiff-base is only a useful additive for the epoxidation of cyclooctene. Due to phase transfer effects it is difficult to compare two-phase systems (solvent dichloromethane (DCM)) to one-phase systems (solvent tert-butanol). A correlation between rotation speed of the stirrer and the turnover frequency was observed.
A Mechanistic Insight Leads to a Greatly Improved Osmium-Catalyzed Asymmetric Dihydroxylation Process
Wai, John S. M.,Marko, Istvan,Svendsen, John, S.,Finn, M. G.,Jacobsen, Eric N.,Sharpless, K. Barry
, p. 1123 - 1125 (1989)
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Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
supporting information, p. 9140 - 9146 (2021/11/23)
The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
Nitrogen Dioxide Catalyzed Aerobic Oxidative Cleavage of C(OH)–C Bonds of Secondary Alcohols to Produce Acids
Liu, Mingyang,Zhang, Zhanrong,Song, Jinliang,Liu, Shuaishuai,Liu, Huizhen,Han, Buxing
supporting information, p. 17393 - 17398 (2019/11/11)
Stable organic nitroxyl radicals are an important class of catalysts for oxidation reactions, but their wide applications are hindered by their steric hinderance, high cost, complex operation, and separation procedures. Herein, NO2 in DMSO is shown to effectively catalyze the aerobic oxidative cleavage of C(OH)?C bonds to form a carboxylic group, and NO2 was generated in situ by decomposition of nitrates. A diverse range of secondary alcohols were selectively converted into acids in excellent yields in this transition-metal-free system without any additives. Preliminary results also indicate its applicability to depolymerize recalcitrant macromolecular lignin. Detail studies revealed that NO2 from nitrates promoted the reaction, and NO2 served as hydrogen acceptor and radical initiator for the tandem oxidative reaction.
Visible light-promoted dihydroxylation of styrenes with water and dioxygen
Yang, Bo,Lu, Zhan
supporting information, p. 12634 - 12637 (2017/12/02)
An efficient visible light promoted metal-free dihydroxylation of styrenes with water and dioxygen has been developed for the construction of vicinal alcohols. The protocol was operationally simple with a broad substrate scope. The mechanistic studies demonstrated that one of the hydroxyl groups came from water and the other one came from molecular oxygen. Additionally, the β-alkyoxy alcohols could also be obtained using a similar strategy.