286-62-4Relevant academic research and scientific papers
Reaction of cyclooctenes with singlet oxygen. Trapping of a perepoxide intermediate
Poon, Thomas H. W.,Pringle, Kenneth,Foote, Christopher S.
, p. 7611 - 7618 (1995)
The products and rate constants for total physical and chemical quenching (kq + kr) of singlet oxygen (1O2) by cis- and trans-cyclooctene were determined in two solvents of different polarity. Small amounts of cis-cyclooctene are produced during the reaction of the trans-isomer. In CDCl3 and acetone-d6, kq + kr for cis-cyclooctene was 1.3 × 104 M-1 s-1 while the rate constants (kr) for the reaction of trans-cyclooctene were 2.3 × 104 and 3.4 × 104 M-1 s-1, respectively. Competition experiments with 2-methyl-2-pentene (2M2P) suggest a substantial contribution of physical quenching for the trans-alkene while the cis-alkene removes 1O2 mostly by chemical reaction. The physical quenching of 1O2 by trans-cyclooctene is explained by a perepoxide intermediate which can open to a zwitterion that can abstract an allylic hydrogen to give the 3-hydroperoxycyclooctene ene product or isomerize and lose O2 to form cis-cyclooctene. A perepoxide intermediate can be trapped using triphenyl phosphite with trans-but not cis-cyclooctene. trans-Cyclooctene quenches 3C70 with a rate constant of 3.4 × 105 M-1 s-1.
Alkene epoxidation catalyzed by manganese complexes with electronically modified 1,10-phenanthroline ligands
Goldsmith, Christian R.,Jiang, Wenchan
, p. 340 - 344 (2012)
The syntheses and alkene epoxidation activities of four manganese(II) complexes with electronically modified 1,10-phenanthroline ligands are reported. Each phenanthroline has a different substituent in the 5-position; the placement ensures that the modifications influence the reactivity through largely electronic effects. All four manganese complexes catalyze the conversion of alkenes to epoxides by commercially available peracetic acid. With each of the four alkenes investigated, the yield of the epoxide product is greater when the 5-substituent on the catalyst is strongly electron-donating, contrary to what has been observed with reactions catalyzed by manganese-salen complexes.
Synthesis of carbon quantum dots/SiO2 porous nanocomposites and their catalytic ability for photo-enhanced hydrocarbon selective oxidation
Han, Xiao,Han, Yuzhi,Huang, Hui,Zhang, Hengchao,Zhang, Xing,Liu, Ruihua,Liu, Yang,Kang, Zhenhui
, p. 10380 - 10383 (2013)
We report a facile hydrolytic process for the preparation of CQDs/SiO 2 porous nanocomposites, which show high catalytic activity and stability for the selective oxidation of cis-cyclooctene under visible light irradiation, with TBHP as a radical initiator and oxygen (in the air) as an oxidant at 80 °C.
A nitrate bridged one-dimensional copper(II) coordination polymer with a tridentate (NNO) Schiff base: synthesis, X-ray structure and catalytic efficacy
Chowdhury, Habibar,Bera, Rajesh,Rizzoli, Corrado,Adhikary, Chandan
, p. 605 - 612 (2020)
A one-dimensional Cu(II) coordination polymer of [Cu(L)(μ-ONO2)]n (1) (HL = 4-methoxy-2-[1-(methylaminoethylimino)methyl]-phenol) with bidentate bridging nitrate has been isolated and characterized by X-ray diffraction analysis and spectroscopic studies. Single crystal?X-ray analysis revealed that each copper(II) center in the asymmetric unit of complex 1 adopts a distorted square pyramidal geometry with a CuN2O3 chromophore ligated through a tridentate Schiff base (L) with (NNO) donor sets and two O atoms of bridging nitrate ion. The adjacent copper atoms are connected by bridging nitrate (μ-ONO2) in bidentate fashion affording a 1D coordination polymeric chain structure along the?crystallographic b-axis. In the polymeric framework, the Cu…Cu separation is 4.3749(4) ?. The catalytic efficacy of complex 1 was studied in a series of solvents for the epoxidation of cyclooctene using tert-butyl-hydroperoxide (TBHP) as an efficient oxidant under mild conditions. The catalytic reaction mixture was analyzed by gas chromatography and the data indicated that the yield of the epoxidation?reaction and its selectivity is maximum in acetonitrile medium.
A novel platform for modeling oxidative catalysis in non-heme iron oxygenases with unprecedented efficiency
Company, Anna,Goì?mez, Laura,Fontrodona, Xavier,Ribas, Xavi,Costas, Miquel
, p. 5727 - 5731 (2008)
A study was conducted to demonstrate a number of non-heme iron complexes, based on the methylpyridine derivatized triazacyclononane (TACN) backbone. It was found that these iron complexes show significant efficiency in the stereospecific oxidation of alkanes with H2O2, bypassing the latest oxidations catalyzed by TPA and BPMEN complexes. It was also demonstrated that the type of substitution on the N atoms of the triazamacrocyle and on the pyridine ring are key tools, to control the selectivity of the iron complexes in catalytic alkane and alkene oxidation reactions. It was also shown that this structural control of the catalytic selectivity in bioinspired oxidation reactions makes the iron complexes an efficient platform, to mimic iron dependent oxygenase reactivity.
Amphiphilic Mesoporous Poly(Ionic Liquid) Immobilized Heteropolyanions Towards the Efficient Heterogeneous Epoxidation of Alkenes with Stoichiometric Hydrogen Peroxide
Shi, Yuming,Guo, Zengjing,Wang, Qian,Zhang, Lingyu,Li, Jing,Zhou, Yu,Wang, Jun
, p. 4426 - 4436 (2017)
New mesoporous poly(ionic liquid)s (MPILs) that feature a pure polycationic framework and tunable hydrophobicity were synthesized through the free-radical polymerization of alkyl-functionalized ionic liquids (ILs) and bisvinylimidazolium salt. Phosphotung
Tantalum-Polyhedral Oligosilsesquioxane Complexes as Structural Models and Functional Catalysts for Epoxidation
Guillo, Pascal,Lipschutz, Michael I.,Fasulo, Meg E.,Tilley, T. Don
, p. 2303 - 2312 (2017)
Tantalum-based supported catalysts have been shown to be very selective for epoxidations with aqueous hydrogen peroxide. To gain information relative to the active site on the surface, access to molecular complexes that mimic the active site of the catalyst on the surface is of great interest. In this contribution, several new Ta-polyhedral oligosilsesquioxane (POSS) complexes with POSS ligands are used to model silica-bound Ta sites and are shown to be active as epoxidation catalysts. Notably, a Ta-POSS complex modified by germanoxy ligands and possessing a dinuclear Ta(μ-O)(μ-OH)Ta core is observed to be very efficient for the epoxidation of cyclooctene using aqueous hydrogen peroxide.
Microwave assisted one pot synthesis and characterization of Cesium salt of di-copper substituted phosphotungstate and its application in the selective epoxidation of cis-cyclooctene with tert-butyl hydroperoxide
Patel, Anjali,Sadasivan, Rajesh
, p. 101 - 108 (2017)
In the present work, we have isolated di-copper substituted phosphotungstate, Cs7[PW10Cu2(H2O)2O38]·9H2O, as a single isomer using novel microwave technique from the commercially
Fluorinated solvents in methyltrioxorhenium-catalyzed olefin epoxidations
Altmann, Philipp,Cokoja, Mirza,Kuehn, Fritz E.
, p. 3235 - 3239 (2012)
Epoxidations with methyltrioxorhenium(VII) (MTO) as catalyst precursor and additives are examined in fluorinated solvents under various conditions. These fluorinated solvents have a strong influence on the 1H NMR, 13C NMR, and 17O NMR spectroscopic data of the catalyst precursor, apparently contributing significantly to the catalytic activity of such systems. Accordingly, the highest turnover frequencies (TOF) obtained with MTO-containing systems have been determined, reaching up to 39000 h -1. Despite the high initial activity, such systems show a pronounced sensitivity to water leading also to faster catalyst decomposition. The high activity as well as the high sensitivity of the catalyst may be due to its solvent-enhanced higher Lewis acidity, leading to quantitative epoxide yields only when quite stable epoxides are the end products and very high amounts of Lewis base additives are applied.
Alkene epoxidation catalysed by ligand-bound supported metalloporphyrins
Cooke, Paul R.,Lindsay Smith, John R.
, p. 2737 - 2740 (1992)
Iron(III) and manganese(III) tetra(2,6-dichlorophenyl)porphyrin bound to surface imidazole and pyridine groups on solid supports are efficient catalysts for the expoxidation of cyclooctene by iodosylbenzene.
