74877-18-2Relevant articles and documents
Synthesis of Molybdenum Chelate-Bonded Fe3O4 Nanoparticles and Their Efficient Catalytic Activity in Epoxidation of Alkenes
Gorjizadeh, M.,Menati, S.,Mohseni, E.,Sayyahi, S.
, p. 1789 - 1793 (2021/11/01)
Abstract: Immobilization of Mo(VI) ions on magnetic nanoparticles has been performed using surface modification of Fe3O4 with 2-hydroxy-5-(2-nitrophenyldiazenyl)benzaldehyde (HNPABA). The new nanomagnetic-supported organocatalyst (Fe3O4@SiO2?HNPABA?Mo(VI)) has been applied in epoxidation of olefins with tert-butyl hydroperoxide. The results indicate that Fe3O4@SiO2?HNPABA?Mo(VI) magnetic nanoparticles demonstrate excellent activity and high stability. The effect of several parameters such as a solvent, catalyst, oxidant content, and temperature has been studied. In addition, the catalyst could be repeatedly applied up to five times without loss of activity in epoxidation of alkenes.
Synthesis and characterization of a new poly α-amino acid Co(II)-complex supported on magnetite graphene oxide as an efficient heterogeneous magnetically recyclable catalyst for efficient free-coreductant gram-scale epoxidation of olefins with molecular oxygen
Kazemnejadi, Milad,Mahmoudi, Boshra,Sharafi, Zeinab,Nasseri, Mohammad Ali,Allahresani, Ali,Esmaeilpour, Mohsen
, p. 59 - 69 (2019/06/13)
A novel magnetic nanocomposite was prepared by immobilization of a cobalt complex of a synthetic poly α-amino acid on Fe3O4-doped graphene oxide (GO/Fe3O4@PAA Co(II)) and was demonstrated to be a highly efficient catalyst for the epoxidation of olefins in mild conditions. PAA was synthesized through a multi-step synthesis, first by a poly condensation reaction of salicylaldehyde followed by the Strecker synthesis. The synthesized nanocomposite was characterized by various analytical and spectroscopic methods including FTIR, ICP, XRD, EDX, XPS, FE-SEM, TEM, TGA, VSM and DLS analyses. A wide variety of olefins could be tolerated toward epoxidation in the presence of molecular oxygen without the need for any co-reductant. The magnetic nanocomposite could be readily separated by a magnet from the mixture and reused for several times without any significant reactivity loss, which represents its potential for practical and industrial application. Also, the scalability of the process was investigated in this work.
Co(II) Schiff base complex decorated on polysalicylaldehyde as an efficient, selective, heterogeneous and reusable catalyst for epoxidation of olefins in mild and self-coreductant conditions
Kazemnejadi, Milad,Shakeri, Alireza,Nikookar, Mahsa,Mohammadi, Mohammad,Esmaeilpour, Mohsen
, p. 6889 - 6910 (2017/10/05)
Abstract: A new Co(II)-Schiff base complex was decorated on a polysalicylaldehyde (PSA) framework and used as a selective and efficient catalyst for the epoxidation of alkenes in the presence of O2 as a green source of oxygen without aco-reductant. The catalyst was characterized step by step by FTIR, UV–Vis, 1H NMR, TGA, CHN, XPS and EDX analyses. Loading an amount of Co ions in the catalyst as well as its leaching amount were studied by an ICP-OES instrument. The catalyst demonstrated excellent activity for the of a variety of alkenes in a mild, inexpensive and efficient protocol. Also, the catalyst can be simply recovered from the reaction mixture and reused for several times without any noteiceable loss in its activity. Reaction parameters including temperature, oxygen flow volume, catalyst amount and solvent were screened by reaction time. Catalytic studies including XPS spectroscopy and some blank experiments were performed to obtain an initial insight into the reaction mechanism. Also, the reactivity of the novel catalyst was evaluated as the turnover frequency. Graphical Abstract: A new and efficient protocol have been developed for the selective epoxidation of olefins using a heterogeneous recyclable Co(II)-Schiff base complex of polysalicylaldehyde in mild and self-coreductant conditions by molecular oxygen.
Epoxidation of olefins by β-bromoalkoxydimethylsulfonium ylides
Majetich, George,Shimkus, Joel,Li, Yang
supporting information; experimental part, p. 6830 - 6834 (2011/03/18)
Olefins can be converted to their respective epoxides in a one-pot procedure by dissolving the olefin in anhydrous DMSO, adding NBS to the reaction mixture to generate a β-bromoalkoxydimethylsulfonium ylide, and then adding DBU to the reaction mixture. A large variety of alkenes were successfully epoxi-dized with yields largely dependent on the structure of the alkene. Most importantly, the facial selectivity of this one-pot process is the opposite of that observed when using traditional epoxidizing reagents. Electron-poor alkenes are not epoxidized under these conditions.
Ring expansion by in situ tethering of hydroxy azides to ketones: The boyer reaction
Gracias, Vijaya,Frank, Kristine E.,Milligan, Gregory L.,Aube, Jeffrey
, p. 16241 - 16252 (2007/10/03)
Although alkyl azides can react with ketones to form ring- expanded lactams, the reaction suffers from poor generality and the need to use powerful Lewis acid promotion. The reactions of 1,2- and 1,3-hydroxyalkyl azides with ketones yield N-hydroxyalkyl lactams in high yields under the action of protic or Lewis acids such as BF3·OEt2. The reaction appears to succeed due to the initial formation of a hemiketal, which then renders the attack of azide on an oxonium ion intramolecular. The scope of this reaction vis a vis ketone and hydroxyalkyl azide structure is discussed.
Kinetics and mechanism of the epoxidation of alkyl-substituted alkenes by hydrogen peroxide, catalyzed by methylrhenium trioxide
Al-Ajlouni, Ahmad M.,Espenson, James H.
, p. 3969 - 3976 (2007/10/03)
Epoxidations of alkyl-substituted alkenes, with hydrogen peroxide as the oxygen source, are catalyzed by CH3ReO3 (MTO). The kinetics of 28 such reactions were studied in 1:1 CH3CN-H2O at pH 1 and in methanol. To accommodate the different requirements of these reactions, 1H-NMR, spectrophotometric, and thermometric techniques were used to acquire kinetic data. High concentrations of hydrogen peroxide were used, so that diperoxorhenium complex CH3Re(O)(η2-O2)2(H 2O), B, was the only predominant and reactive form of the catalyst. The reactions between B and the alkenes are about 1 order of magnitude more rapid in the semiaqueous solvent than in methanol. The various trends in reactivity are medium-independent. The rate constants for B with the aliphatic alkenes correlate closely with the number of alkyl groups on the olefinic carbons. The reactions become markedly slower when electron-attracting groups, such as halo, hydroxy, cyano, and carbonyl, are present. The rate constants for catalytic epoxidations with B and those reported for the stoichiometric reactions of dimethyldioxirane show very similar trends in reactivity. These findings suggest a concerted mechanism in which the electron-rich double bond of the alkene attacks a peroxidic oxygen of B. These data, combined with those reported for the epoxidation of styrene (a term intended to include related molecules with ring and/or aliphatic substituents) by B and by the monoperoxo derivative of MTO, suggest that all of the rhenium-catalyzed epoxidations occur by a common mechanism. The geometry of the system at the transition state can be inferred from these data, which suggest a spiro arrangement.
A simple one-pot preparation of (Z)-cyclopropanes from γ,δ-ketoalkenes using KOH/DMSO intramolecular alkylation conditions
Dechoux, Luc,Ebel, Maurice,Jung, Louis,Stambach, Jean Francois
, p. 7405 - 7408 (2007/10/02)
Sequential treatment of λ,δ-ketoalkenes with aqueous NBS in DMSO and KOH as solid provides (Z)-cyclopropanes in good overall yields with a diastereoselective excess>;99%.
