148076-33-9Relevant academic research and scientific papers
Kinetics of MTO-catalyzed oferin epoxidation in ambient temperature ionic liquids: UV/Vis and 2H NMR study
Owens, Gregory S.,Durazo, Armando,Abu-Omar, Mahdi M.
, p. 3053 - 3059 (2002)
The kinetics of oxygen-atom transfer from the peroxo complexes of methyltrioxorhenium (MTO) to alkenes in ionic liquids have been investigated. Noncatalytic conversions of alkenes to epoxide were monitored by UV/Vis at 360 nm, where the monoperoxorhenium
Deuterium NMR spectroscopy is a versatile and economical tool for monitoring reaction kinetics in ionic liquids
Durazo, Armando,Abu-Omar, Mahdi M.
, p. 66 - 67 (2002)
Time-resolved 2H NMR spectroscopy is used to monitor the progress of and gain kinetic information for a variety of reactions in different ionic media.
A putative heme manganese(v)-oxo species in the C-H activation and epoxidation reactions in an aqueous buffer
Harmalkar, Dinesh S.,Santosh,Shetgaonkar, Siddhi B.,Sankaralingam, Muniyandi,Dhuri, Sunder N.
supporting information, p. 12900 - 12906 (2019/08/28)
A water-soluble manganese(v)-oxo species 1 was generated in the reaction of [Mn(iii)(TPPS)Cl] 2 (TPPS = 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine) and iodosylbenzene (PhIO) in a 2:1 aqueous buffer (pH = 10.4):acetonitrile (CH3CN) mixture. The formula of the EPR silent species 1 is proposed as [Mn(v)(O)(TPPS)Cl] based on the Soret band (422 nm) and Q bands (520, 660 nm) in its UV-vis spectrum and its reaction with thioanisole, regenerating 2 and methyl phenyl sulfoxide. The reactivity of 1 was investigated in the C-H activation of alkyl hydrocarbons and epoxidation of cyclohexene. Based on the observation of the linear correlation of the logarithm of the second rate constant (logk2′) and the bond dissociation energy (BDE, kcal mol-1) of alkyl hydrocarbons along with a large kinetic isotope effect (KIE = 8.5) for xanthene vs. xanthene-d2, we propose H-atom abstraction as the rate determining step in the C-H activation reactions. On the other hand, in contrast to the C-H activation reaction, cyclohexene, which has a weak C-H bond (BDE = 82.5 kcal mol-1), undergoes an epoxidation reaction.
Mononuclear Nonheme High-Spin Iron(III)-Acylperoxo Complexes in Olefin Epoxidation and Alkane Hydroxylation Reactions
Wang, Bin,Lee, Yong-Min,Clémancey, Martin,Seo, Mi Sook,Sarangi, Ritimukta,Latour, Jean-Marc,Nam, Wonwoo
supporting information, p. 2426 - 2436 (2016/03/05)
Mononuclear nonheme high-spin iron(III)-acylperoxo complexes bearing an N-methylated cyclam ligand were synthesized, spectroscopically characterized, and investigated in olefin epoxidation and alkane hydroxylation reactions. In the epoxidation of olefins, epoxides were yielded as the major products with high stereo-, chemo-, and enantioselectivities; cis- and trans-stilbenes were oxidized to cis- and trans-stilbene oxides, respectively. In the epoxidation of cyclohexene, cyclohexene oxide was formed as the major product with a kinetic isotope effect (KIE) value of 1.0, indicating that nonheme iron(III)-acylperoxo complexes prefer C? - ?C epoxidation to allylic C-H bond activation. Olefin epoxidation by chiral iron(III)-acylperoxo complexes afforded epoxides with high enantioselectivity, suggesting that iron(III)-acylperoxo species, not high-valent iron-oxo species, are the epoxidizing agent. In alkane hydroxylation reactions, iron(III)-acylperoxo complexes hydroxylated C-H bonds as strong as those in cyclohexane at -40 °C, wherein (a) alcohols were yielded as the major products with high regio- and stereoselectivities, (b) activation of C-H bonds by the iron(III)-acylperoxo species was the rate-determining step with a large KIE value and good correlation between reaction rates and bond dissociation energies of alkanes, and (c) the oxygen atom in the alcohol product was from the iron(III)-acylperoxo species, not from molecular oxygen. In isotopically labeled water (H218O) experiments, incorporation of 18O from H218O into oxygenated products was not observed in the epoxidation and hydroxylation reactions. On the basis of mechanistic studies, we conclude that mononuclear nonheme high-spin iron(III)-acylperoxo complexes are strong oxidants capable of oxygenating hydrocarbons prior to their conversion into iron-oxo species via O-O bond cleavage.
Oxygenation of Styrene by Cytochrome P-450 Model Systems: A Mechanistic Study
Collman, James P.,Kodadek, Thomas,Brauman, John I.
, p. 2588 - 2594 (2007/10/02)
The manganese and iron porphyrin catalyzed oxygenation of styrene results in the production of phenylacetaldehyde as well as the expected epoxide.It is demonstrated that aldehyde is a primary product and dose not result from isomerization of styrene oxide.Isotope labeling studies show that one of the β hydrogen atoms of styrene migrates to the benzylic carbon in the course of aldehyde formation.Experiments using cis and trans deuterated styrenes reveal that there is a stereoelectronic preference for migration of the hydrogen cis to the aromatic ring.Styrene, styrene-d8, and cis-β-deuteriostyrene yield similar ratios of epoxide to aldehyde, indicating that β hydrogen migration occurs after the rate-determining step for formation of phenylacetaldehyde.The mechanism of this rearrangement is discussed.Some new information concerning the mechanism of olefin epoxidation by these catalysts is also presented.These results may have relevance to the mechanism of alkene oxygenation by the cytochrome P-450 monooxygenase enzymes.
