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141-79-7Relevant articles and documents
CYCLO-ELIMINATION OF SILYL AND SULPHOXIDE GROUPS IN COMPETITION WITH THE CONVENTIONAL CYCLO-ELIMINATION OF SULPHOXIDES
Fleming, Ian,Perry, David A.
, p. 5095 - 5096 (1981)
The β-silylsulphoxides (2 and 4) undergo a fast syn-elimination to give the alkene (3) and the alkyne (6), respectively; however, when there is a hydrogen α to the silyl group, only hydrogen is lost, and the products are β-silylenones.
Highly Stereoselective Synthesis of α,β-Unsaturated Ketones by CeCl3 Mediated Addition of Grignard Reagents to β-Enamino Ketones
Bartoli, Giuseppe,Cimarelli, Cristina,Marcantoni, Enrico,Palmieri, Gianni,Petrini, Marino
, p. 715 - 716 (1994)
A stereoselective synthesis of α,β-unsaturated ketones by direct addition of Grignard reagents to β-enamino ketones, mediated by dry cerium(III) chloride, is described and a trans relationship between the introduced framework and the carbonyl group is predominantly observed.
Fluoride adducts of niobium(V): Activation reactions and alkene polymerizations
Hayatifar, Mohammad,Marchetti, Fabio,Pampaloni, Guido,Patil, Yogesh,Raspolli Galletti, Anna Maria
, p. 214 - 218 (2013)
Fluoride coordination derivatives of niobium(V) were tested for their activation capabilities with respect to acetone and to olefins. Activation of acetone (formation of mesityloxide) was observed with NbF4(OMe). Several fluoride coordination derivatives of niobium(V) of different nature (neutral or ionic) and nuclearity, i.e. NbF5L [L = Et2O, 4, thf, 5 (thf is tetrahydrofuran), MeOH, 6, EtOH, 7], (NbF4L 2)(NbF6) [L = dmf, 8 (dmf is dimethylformamide), dme, 9 (dme is dimethoxyethane)], (NbF4L4)(NbF6) [L = thf, 10, Et2O, 11, MeCN, 12], [S(NMe)3][NbF6], 13, NbF4OMe, 1, NbF4OPh, 3), NbF3(OPh) 2, 14, NbF2(OPh)3, 15 and NbF 2(OEt)3, 16, promoted the polymerization of ethylene using AlMe3-depleted methylaluminoxane as cocatalyst. Highly linear polyethylene was obtained. Compound 3, upon activation with methylaluminoxane, promoted ring-opening metathesis polymerization (ROMP) of norbornene, affording polymers with a slight excess of trans content.
Tricyanomethane and Its Ketenimine Tautomer: Generation from Different Precursors and Analysis in Solution, Argon Matrix, and as a Single Crystal
Banert, Klaus,Chityala, Madhu,Hagedorn, Manfred,Beckers, Helmut,Stüker, Tony,Riedel, Sebastian,Rüffer, Tobias,Lang, Heinrich
, p. 9582 - 9586 (2017)
Solutions of azidomethylidenemalononitrile were photolyzed at low temperatures to produce the corresponding 2H-azirine and tricyanomethane, which were analyzed by low-temperature NMR spectroscopy. The latter product was also observed after short thermolysis of the azide precursor in solution whereas irradiation of the azide isolated in an argon matrix did not lead to tricyanomethane, but to unequivocal detection of the tautomeric ketenimine by IR spectroscopy for the first time. When the long-known “aquoethereal” greenish phase generated from potassium tricyanomethanide, dilute sulfuric acid, and diethyl ether was rapidly evaporated and sublimed, a mixture of hydronium tricyanomethanide and tricyanomethane was formed instead of the previously claimed ketenimine tautomer. Under special conditions of sublimation, single crystals of tricyanomethane could be isolated, which enabled the analysis of the molecular structure by X-ray diffraction.
INFRARED STUDY OF THE REACTIVITY OF ACETONE AND HEXACHLOROACETONE ADSORBED ON HAEMATITE
Busca, Guido,Lorenzelli, Vincenzo
, p. 2911 - 2920 (1982)
Infrared spectra of acetone adsorbed at beam temperature on α-Fe2O3 show that acetone can chemisorb on Lewis-acid sites and gives, at least partially, enolate anions; these, by aldolic condensation with molecules from the gas phase, produce a chemisorbed form of mesityl oxide.At 523 K acetate ions are formed.Two different forms of trichloroacetate ions are formed on the surface at beam temperature by the adsorption of hexachloroacetone and trichloroacetic acid.This behaviour indicates the presence of pairs of acid-base sites on the surface of haematite, and also shows that its surface hydroxy groups have a lower degree of nucleophilic character with respect to those of other oxides such as aluminas, SnO2 and alkaline-earth oxides.
Acetone condensation over CaO—SnO2 catalyst
Koklin,Hasyanova,Glukhov,Bogdan
, p. 488 - 490 (2017)
Aldol condensation of acetone was studied over solid base CaO—SnO2 catalyst in the 300—450 °C temperature range and at 15—75 atm pressure in a fixed-bed reactor. The main products are mesityl oxide and isophorone. The high stability of CaO—SnO2 catalyst performance was observed at pressure of 75 atm giving the acetone conversion of 36—41%. Increase in the temperature and pressure led to a simultaneous raise in acetone conversion. The maximum conversion of 41% was achieved at 400 °C, 75 atm and a flow rate of acetone of 8.1 g h–1 (g catalyst)–1.
Facile rearrangement of 3-oxoalkyl radicals is evident in low-temperature gas-phase oxidation of ketones
Scheer, Adam M.,Welz, Oliver,Sasaki, Darryl Y.,Osborn, David L.,Taatjes, Craig A.
, p. 14256 - 14265 (2013)
The pulsed photolytic chlorine-initiated oxidation of methyl-tert-butyl ketone (MTbuK), di-tert-butyl ketone (DTbuK), and a series of partially deuterated diethyl ketones (DEK) is studied in the gas phase at 8 Torr and 550-650 K. Products are monitored as a function of reaction time, mass, and photoionization energy using multiplexed photoionization mass spectrometry with tunable synchrotron ionizing radiation. The results establish that the primary 3-oxoalkyl radicals of those ketones, formed by abstraction of a hydrogen atom from the carbon atom in γ-position relative to the carbonyl oxygen, undergo a rapid rearrangement resulting in an effective 1,2-acyl group migration, similar to that in a Dowd-Beckwith ring expansion. Without this rearrangement, peroxy radicals derived from MTbuK and DTbuK cannot undergo HO2 elimination to yield a closed-shell unsaturated hydrocarbon coproduct. However, not only are these coproducts observed, but they represent the dominant oxidation channels of these ketones under the conditions of this study. For MTbuK and DTbuK, the rearrangement yields a more stable tertiary radical, which provides the thermodynamic driving force for this reaction. Even in the absence of such a driving force in the oxidation of partially deuterated DEK, the 1,2-acyl group migration is observed. Quantum chemical (CBS-QB3) calculations show the barrier for gas-phase rearrangement to be on the order of 10 kcal mol-1. The MTbuK oxidation experiments also show several minor channels, including β-scission of the initial radicals and cyclic ether formation.
A convenient deoxygenation fo α,β-epoxy ketones to enones
Dos Santos, Reginaldo B.,Brocksom, Timothy John,Brocksom, Ursula
, p. 745 - 748 (1997)
A new and efficient methodology for the deoxigenation of α,β-epoxy ketones to enones has been developed, using aminoiminomethanesulfinic acid (thioulea dioxide) as the reducing agent under phase transfer conditions. The epoxides of mesityl oxide, isophorane (-)-carvone, (+)-6-methyl-carvone, (+)-6-ethyl-carvone and (-)-myrtenal, were converted into their respectives enones in good to excellent yields.
In-situ IR Spectroscopy Study of Reactions of C3 Oxygenates on Heteroatom (Sn, Mo, and W) doped BEA Zeolites and the Effect of Co-adsorbed Water
Najmi, Sean,So, Jungseob,Stavitski, Eli,McDermott, William P.,Lyu, Yimeng,Burt, Sam P.,Hermans, Ive,Sholl, David S.,Sievers, Carsten
, p. 445 - 458 (2021)
The reactions of acetone and hydroxyacetone over heteroatom doped BEA zeolites (Sn, Mo, and W) in the presence and absence of H2O vapor are investigated using infrared spectroscopy. Acetone is converted to mesityl oxide over Sn-BEA exclusively. At higher temperatures, larger oxygenates such as phorones, aromatics, and coke form. The presence of co-adsorbed water in Sn-BEA suppresses tautomerization. H2O vapor is also beneficial for minimizing coke formation at high temperatures. Hydroxyacetone is converted into 2-hydroxypropanal over Sn-BEA, exhibiting high affinity to Sn sites up to 400 °C. Sn-BEA catalyzes conversion of hydroxyacetone into the enol in the absence of H2O, but exposure to H2O induces the formation of 2-hydroxypropanal and subsequent conversion to acrolein. The Lewis acid descriptors are used to rationalize the reaction pathways. For the isomerization of hydroxyacetone into 2-hydroxypropanal, the hardness of acid sites influences the reaction and correlates with the overall Lewis acidity of the catalysts, respectively. However, the size of the exchanged metal significantly affects aldol condensation, where keto and enol forms of acetone adsorb to active sites simultaneously.
Silica Chloride (SiO2-Cl) and Trimethylsilyl Chloride (TMSCl) Promote Facile and Efficient Dehydration of Tertiary Alcohols
Firouzabadi, Habib,Iranpoor, Naser,Hazarkhani, Hassan,Karimi, Babak
, p. 3653 - 3660 (2003)
Silica chloride (SiO2-Cl), as a heterogeneous reagent, has been used for the efficient dehydration of tertiary alcohols under mild reaction conditions. For comparison, we have also used trimethylsilyl chloride (TMSCl) as a homogeneous reagent for this purpose. We have found that silica chloride is a more efficient reagnet than trimethylsilyl chloride for this purpose. Handling of SiO2-Cl is much safer and easier than TMSCl, especially for large-scale operation. The selectivity of the method is also demonstrated by several competitive reactions. Ether formation, rearranged products, and polymerization have not been observed in the reactions.
