5076-19-7Relevant academic research and scientific papers
Study of the addition of monoalkylphosphonic acids onto trialkyl-substituted epoxides
Derouet,Cauret,Brosse
, p. 3767 - 3774 (2001)
The addition of 2-chloroethylphosphonic acid (or ethephon), a well-known stimulating molecule for the production of latex by Hevea brasiliensis, onto 2,3-epoxy-2-methylbutane was investigated to enhance the understandings on the addition mechanisms of reagents of alkylphosphonic acid type onto trialkyl-substituted epoxides. It was demonstrated that the addition occurs according to a three-step mechanism including a rapid nucleophilic attack of the phosphorated anion on the most alkyl-substituted carbon of the oxirane, followed by formation of a dioxaphospholane structure with release of water, and finally a hydrolytic cleavage of the dioxaphospholane cycle to generate the regioisomer 1:1 adduct where the phosphorated group is on the less alkyl-substituted carbon of the initial oxirane.
Kinetics of 2-methylbutene-2 epoxidation with 2-methylbutane hydroperoxide
Petukhova,Sapunov,Kharlampidi,Petukhov
, p. 381 - 387 (2010)
The kinetics of 2-methylbutene-2 epoxidation with 2-methylbutane hydroperoxide was studied in the presence of a molybdenum catalyst. The mathematical description of the hydroperoxide consumption and 2-methyl-butene-2 oxide formation was derived, and the most probable scheme of the process was suggested. The main kinetic constants were calculated.
ESR Evudence for Localized Forms of C - C Ring-Opened Oxirane Radical Cations
Qin, Xue-Zhi,Snow, Larry D.,Williams, Ffrancon
, p. 3602 - 3606 (1985)
Localized forms of the C...C ring-opened oxirane and methyl-substituted oxirane radical cations have been detected by ESR spectroscopy following γ-irradiation of solid solutions of the parent compounds in the CFCl2CF2Cl matrix.For oxirane, 1,2-dimethyloxirane, and tetramethyloxirane, he localized forms possess the RCH2., RCHMe., and the RCMe2. radical centers, respectively.In the unsymmetrically substituted methyloxiranes, the radical center is localized at the oxirane carbon with the least number of methyl groups.The temperature needed to bring about the formation of of the localized species increases with methyl substitution at the localized radical center, the oxirane and methoxirane species being formed during irradiation at 77 K while the tetramethyloxirane species is produced subsequently from the delocalized planar form of the of ring-opened cation at 105-110 K.In contrast, only the delocalized forms of the oxirane cations have been observed in CFCl3, CF3CCl3, and CCl4, even at much higher temperatures (145-215 K) close to the softening points of these matrices.The possible structures of the localized forms of the oxirane radical cations are discussed, the two most reasonable models being either an orthogonal structure with noninteracting radical and carbocation centers or a similar species in which the carbocation center is complexed with the solvent or combined with a chloride ion.Despite the lack of ESR and other evidence for some type of solvent haloen participation in the localized structure, the latter model cannot be ruled out at present.
Catalytic Radical-Polar Crossover Reactions of Allylic Alcohols
Touney, Eric E.,Foy, Nicholas J.,Pronin, Sergey V.
supporting information, p. 16982 - 16987 (2018/12/14)
Radical-polar crossover hydrofunctionalizations of tertiary allylic alcohols are described. Depending on the structure of the catalyst, corresponding epoxides or semipinacol rearrangement products are selectively obtained in good yields. Experimental evidence points to the participation of alkylcobalt complexes as electrophilic intermediates.
Regioselective Organocatalytic Formation of Carbamates from Substituted Cyclic Carbonates
Sope?a, Sergio,Laserna, Victor,Guo, Wusheng,Martin, Eddy,Escudero-Adán, Eduardo C.,Kleij, Arjan W.
supporting information, p. 2172 - 2178 (2016/07/16)
A highly regioselective catalytic approach has been developed towards carbamates derived from cyclic organic carbonates by reaction of the latter with amine reagents under organocatalytic control. For various combinations of carbonate and amine substrates, an organocatalyst (TBD: 1,5,7-triazabicyclo[4.4.0]dec-5-ene) was used to increase the reaction kinetics while exerting excellent regioselective control. The current method is the first general approach towards the control over the regioselectivity of this reaction using a wide variety of easily accessed substituted organic carbonates. (Figure presented.) .
EFFICIENT PROCESS FOR PRODUCING EPOXIDES BY OXIDATION OF OLEFINS IN THE HOMOGENEOUS GAS PHASE
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Page/Page column 2, (2011/06/26)
An economical one-step process is provided for the preparation of epoxides by oxidation of olefins in a homogeneous gas phase reaction, wherein the olefin is reacted in a flow reactor with a gas mixture of ozone and NO2 and/or NO as oxidants without use of a catalyst, and wherein ozone and NO2 and/or NO are mixed in a mixing chamber connected upstream to the flow reactor. The process is characterized in that the olefin in the reaction zone of the flow reactor is reacted at a reaction temperature of approximately 150° C. to approximately 450° C. and a pressure of 250 mbar to 10 bar with the gas mixture of the oxidant, that the carrier gas flow containing the olefin is heated in a preheating zone of the flow reactor to a temperature of 250° C. to 650° C., and that the gas mixture of the oxidant from the mixing chamber, having ambient temperature, is turbulently mixed with the olefin in the reaction zone of the flow reactor, so that the reaction temperature is reached during the mixing and the ratio of olefin-gas flow and gas flow of the oxidant is 5:1 to 1:1.
(4 S,5 S)-2,2,4-Triethyl-5-methyl-1,3-dioxolane: A new volatile released by a triatomine bug
Unelius,Bohman,Lorenzo,Troeger,Franke,Francke
supporting information; experimental part, p. 5601 - 5603 (2011/03/20)
Adults of the triatomine bug Triatoma brasiliensis release 2,2,4-triethyl-5-methyl-1,3-dioxolane (1) as a mixture of the (4S,5S)- and (4R,5R)-enantiomers in a ratio of 4:1. Among the volatile acetals identified from insects so far, this is the first example resulting from an intermolecular condensation of a carbonyl moiety and a diol substructure.
Transition-state geometry measurements from13C isotope effects. the experimental transition state for the epoxidation of alkenes withoxaziridines
Hirschi, Jennifer S.,Takeya, Tetsuya,Hang, Chao,Singleton, Daniel A.
experimental part, p. 2397 - 2403 (2009/07/30)
We here suggest and evaluate a methodology for the measurement of specific interatomic distances from a combination of theoretical calculations and experimentally measured 13C kinetic isotope effects. This process takes advantage of a broad diversity of transition structures available for the epoxidation of 2-methyl-2-butene with oxaziridines. From the isotope effects calculated for these transition structures, a theory-independent relationship between the C-O bond distances of the newly forming bonds and the isotope effects is established. Within the precision of the measurement, this relationship in combination with the experimental isotope effects provides a highly accurate picture of the C-O bonds forming at the transition state. The diversity of transition structures also allows an evaluation of the Schramm process for defining transition-state geometries on the basis of calculations at nonstationary points, and the methodology is found to be reasonably accurate.
WO3 Nanoparticles on MCM-48 as a Highly Selective and Versatile Heterogeneous Catalyst for the Oxidation of Olefins, Sulfides, and Cyclic Ketones
Koo, Dong Hyun,Kim, Min,Chang, Sukbok
, p. 5015 - 5018 (2007/10/03)
It is shown that nanosized WO3 particles supported on MCM-48 work as a highly efficient and selective heterogeneous catalyst for the oxidation of olefins, sulfides, and cyclic ketones using hydrogen peroxide or peracetic acid. The catalytic activity of the supported tungstate was dependent on the nature of the supporting materials and particle size. The catalyst system employs environmentally benign oxidants in halide-free solvents, and it does not require phase-transfer agents and pH control.
Kinetics and mechanism of the liquid-phase rearrangement of 2-Methyl-2,3-epoxybutane in the presence of a magnesium bromide complex
Mel'nik,Khvatova,Moskvichev,Srednev
, p. 275 - 278 (2007/10/03)
The mechanism of intramolecular rearrangement of epoxides in the presence of the MgBr2 · 2H2O · 4DMF catalytic complex was proposed on the basis of a kinetic study of the liquid-phase isomerization of 2-methyl-2,3-epoxybutane and data on the influence of the ligand environment of the catalyst, solvent nature, and the epoxide structure. Copyright
