1003-17-4Relevant academic research and scientific papers
Oxygen Transfer by Dialkylperoxonium Ions
Bloodworth, A. J.,Melvin, T.,Mitchell, John C.
, p. 2612 - 2613 (1986)
Oxygen-transfer from dialkylperoxonium ions R2O+OH has been demonstrated for three such species, where R2 is a hydrocarbon chain or ring, by oxidation of several dialkyl sulfoxides, methyl phenyl sulfide, and the succinimide anion, with concurrent formation of the corresponding cyclic or bicyclic ether R2O.
Rule of five cyclizations in 5-hexenyl radicals and photocycloadditions of 1,5-hexadienes: Effect of 4-oxa substitution
Matlin, Albert R.,Brinton, Karen Feit,Nivaggioli, Belinda Tsao
, p. 83 - 87 (2007)
The effect of 4-oxa substitution on the regiochemistry and rate of 5-hexenyl radical cyclizations was investigated, as a potential model for [2 + 2] photocycloadditions of 2-acyl-4-oxa-1,5-hexadienes. Increasing the electron density in the alkene decreases the rate of cyclization in the 4-oxa-hexejiyl radicals, relative to the all carbon analogs, but has little effect on the regioselectivity of the cyclization. The radical model does not reproduce the high degree of 1,6 closure, observed in the [2 + 2] photocycloadditions for 4-oxa-1,5-hexadiene la. However, the radical model does reinforce the interpretation that ground state conformational effects, engendered by substitution remote from the reacting centers have important rate consequences for cyclization reactions. Copyright
Cyclization of 4-Hydroxy-4-methyl-1-pentyl p-Toluenesulfonate as a Model to Evaluate Inherent Medium Effect on SN2 Solvolysis
Shimizu, Nobujiro,Tsutsumi, Toru,Tsuno, Yuho
, p. 2065 - 2068 (1991)
Solvent effect on the cyclization of 4-hydroxy-4-methyl-1-pentyl p-toluenesulfonate, a mechanistic equivalent to the SN2 solvolysis, was successfully analyzed by Taft LSER equation as log k=3.2?*+1.4α+1.9β-8.36, indicating that three independent factors are operative, i.e., solvent polarity and H-bond donor ability which promote ionization, and H-bond acceptor ability which enhances nucleophilicity of the internal OH group.
Catalytic formation of C-O bonds by alkene activation: Lewis acid-cycloisomerisation of olefinic alcohols
Coulombel, Lydie,Favier, Isabelle,Dunach, Elisabet
, p. 2286 - 2288 (2005)
Tin(IV) trifluoromethanesulfonate has been found to be an excellent catalyst for the cycloisomerisation of non-activated and differently substituted olefinic alcohols to cyclic ethers. The Royal Society of Chemistry 2005.
Water opens the door to organolithiums and Grignard reagents: Exploring and comparing the reactivity of highly polar organometallic compounds in unconventional reaction media towards the synthesis of tetrahydrofurans
Cicco, Luciana,Sblendorio, Stefania,Mansueto, Rosmara,Perna, Filippo M.,Salomone, Antonio,Florio, Saverio,Capriati, Vito
, p. 1192 - 1199 (2016/02/09)
It has always been a firm conviction of the scientific community that the employment of both anhydrous conditions and water-free reaction media is required for the successful handling of organometallic compounds with highly polarised metal-carbon bonds. Herein, we describe how, under heterogeneous conditions, Grignard and organolithium reagents can smoothly undergo nucleophilic additions to γ-chloroketones, on the way to 2,2-disubstituted tetrahydrofurans, "on water", competitively with protonolysis, under batch conditions, at room temperature and under air. The reactivity of the above organometallic reagents has also been investigated in conventional anhydrous organic solvents and in bio-based eutectic and low melting mixtures for comparison. The scope and limitations of this kind of reaction are discussed.
METHOD FOR PREPARING TRIOLS AND DIOLS FROM BIOMASS-DERIVED REACTANTS
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Paragraph 0092; 0093, (2014/09/30)
A method to make triols and diols is described. The method includes the steps of performing an aqueous-phase hydrodeoxygenation reaction on a feedstock containing a biomass-derived reactant in aqueous solution. The feedstock is contacted with a heterogeneous metal-containing bifunctional catalyst or a combination of two or more heterogeneous metal-containing catalysts that catalyze cleavage of C—C and C—O bonds, for a time, temperature, pressure, and weight hourly space velocity to yield a product mix comprising triols, diols, or combinations thereof.
Experimental investigation of the low temperature oxidation of the five isomers of hexane
Wang, Zhandong,Herbinet, Olivier,Cheng, Zhanjun,Husson, Benoit,Fournet, Rene,Qi, Fei,Battin-Leclerc, Frederique
, p. 5573 - 5594 (2014/08/18)
The low-temperature oxidation of the five hexane isomers (n-hexane, 2-methyl-pentane, 3-methyl-pentane, 2,2-dimethylbutane, and 2,3-dimethylbutane) was studied in a jet-stirred reactor (JSR) at atmospheric pressure under stoichiometric conditions between 550 and 1000 K. The evolution of reactant and product mole fraction profiles were recorded as a function of the temperature using two analytical methods: gas chromatography and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Experimental data obtained with both methods were in good agreement for the five fuels. These data were used to compare the reactivity and the nature of the reaction products and their distribution. At low temperature (below 800 K), n-hexane was the most reactive isomer. The two methyl-pentane isomers have about the same reactivity, which was lower than that of n-hexane. 2,2-Dimethylbutane was less reactive than the two methyl-pentane isomers, and 2,3-dimethylbutane was the least reactive isomer. These observations are in good agreement with research octane numbers given in the literature. Cyclic ethers with rings including 3, 4, 5, and 6 atoms have been identified and quantified for the five fuels. While the cyclic ether distribution was notably more detailed than in other literature of JSR studies of branched alkane oxidation, some oxiranes were missing among the cyclic ethers expected from methyl-pentanes. Using SVUV-PIMS, the formation of C 2-C3 monocarboxylic acids, ketohydroperoxides, and species with two carbonyl groups have also been observed, supporting their possible formation from branched reactants. This is in line with what was previously experimentally demonstrated from linear fuels. Possible structures and ways of decomposition of the most probable ketohydroperoxides were discussed. Above 800 K, all five isomers have about the same reactivity, with a larger formation from branched alkanes of some unsaturated species, such as allene and propyne, which are known to be soot precursors.
Calcium catalyzed hydroalkoxylation
Kena Diba, Anastasie,Begouin, Jeanne-Marie,Niggemann, Meike
supporting information, p. 6629 - 6632,4 (2012/12/13)
A calcium catalyzed intramolecular hydroalkoxylation reaction is presented, as a transition metal free, inexpensive, and very mild process for the highly atom economic formation of cyclic ethers from γ,δ-unsaturated alcohols. In contrast to most of the previously reported procedures, room temperature conditions are fully sufficient in most cases for a high yielding cycloisomerization in the presence of a combination of 5 mol-% Ca(NTf 2)2 and 5 mol-% Bu4NPF6. Full regioselectivity is observed in all transformations.
Calcium catalyzed hydroalkoxylation
Kena Diba, Anastasie,Begouin, Jeanne-Marie,Niggemann, Meike
supporting information, p. 6629 - 6632 (2013/01/15)
A calcium catalyzed intramolecular hydroalkoxylation reaction is presented, as a transition metal free, inexpensive, and very mild process for the highly atom economic formation of cyclic ethers from γ,δ-unsaturated alcohols. In contrast to most of the previously reported procedures, room temperature conditions are fully sufficient in most cases for a high yielding cycloisomerization in the presence of a combination of 5 mol-% Ca(NTf 2)2 and 5 mol-% Bu4NPF6. Full regioselectivity is observed in all transformations.
Efficient intramolecular hydroalkoxylation of unactivated alkenols mediated by recyclable lanthanide lriflate ionic liquids: Scope and mechanism
Dzudza, Alma,Marks, Tobin J.
supporting information; experimental part, p. 3403 - 3422 (2010/06/21)
Lanthanide triflate complexes of the type [Ln(OTf)3] (Ln = La, Sm, Nd, Yb, Lu) serve as effective, recyclable catalysts for the rapid intramolecular hydroalkoxylation (HO)/cyclization of primary/secondary and aliphatic/aromatic hydroxyalkenes in imidazolium-based room-temperature ionic liquids (RTILs) to yield the corresponding furan, pyran, spirobicyclic furan, spirobicyclic furan/pyran, benzofuran, and isochroman derivatives. Products are straightforwardly isolated from the catalytic solution, conversions exhibit Markovnikov regioselectivity, and turnover frequencies are as high as 47 h -1 at 120°C. The ring-size rate dependence of the primary alkenol cyclizations is 5>6, consistent with a sterically controlled transition state. The hydroalkoxylation/cyclization rates of terminal alkenols are slightly more rapid than those of internal alkenols, which suggests modest steric demands in the cyclic transition state. Cyclization rates of aryl-functionalized hydroxyalkenes are more rapid than those of the linear alkenols, whereas five- and five/six-membered spirobicyclic skeletons are also regioselectively closed. In cyclization of primary, sterically encumbered alkenols, turnoverfrequency dependence on metal-ionic radius decreases by approximately 80fold on going from La3+ (1.160 A) to Lu3+ (0.977 A), presumably reflecting steric impediments along the reaction coordinate. The overall rate law for alkenol hydroalkoxylation/cyclization is v≈[catalys] 1[alkenol]1. An observed ROH/ROD kinetic isotope effect of 2.48 (9) is suggestive of a catalytic pathway that involves kinetically significant intramolecular proton transfer. The present activation parameters-enthalpy (ΔH≠) = 18.2 (9) Kcal mol-1, entropy (ΔS≠) = -17.0 (1.4) eu, and energy (E,) = 18.2 (8) kcal mol-1-suggest a highly organized transition state. Proton scavenging and coordinative probing results suggest that the lanthanide inflates are not simply precursors of free triflic acid. Based on the kinetic and mechanistic evidence, the proposed catalytic pathway invokes hydroxyl and olefin activation by the electron-deficient Ln3+ center, and intramolecular H+ transfer, followed by alkoxide nucleophilic attack with ring closure.
