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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.
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.
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Huston,Ungnade
, p. 2885 (1940)
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Adkins,Connor
, p. 1095 (1931)
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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.
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Kremann,Hoenel
, p. 1469 (1913)
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France,Maitland,Tucker
, p. 1739,1741 (1937)
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Condensation and esterification reactions of alkanals, alkanones, and alkanols on TiO2: Elementary steps, site requirements, and synergistic effects of bifunctional strategies
Wang, Shuai,Goulas, Konstantinos,Iglesia, Enrique
, p. 302 - 320 (2016)
Rates and selectivity of TiO2-catalyzed condensation of C3 oxygenates (propanal, acetone) are limited by ubiquitous effects of side reactions, deactivation, and thermodynamic bottlenecks. H2 together with a Cu function, present as physical mixtures with TiO2, circumvents such hurdles by scavenging unsaturated intermediates. They also render alkanols and alkanals/alkanones equivalent as reactants through rapid interconversion, while allowing esterification turnovers by dehydrogenating unstable hemiacetals. Oxygenates form molecules with new C-C and C-O bonds and fewer O-atoms at nearly complete conversions with stable rates and selectivities. Kinetic, isotopic, and theoretical methods showed that rates are limited by α-C-H cleavage from carbonyl reactants to form enolate intermediates, which undergo C-C coupling with another carbonyl species to form α,β-unsaturated oxygenates or with alkanols to form hemiacetals with new C-O bonds, via an intervening H-shift that forms alkoxide-alkanal pairs. Titrations with 2,6-di-tert-butylpyridine, pyridine, CO2, and propanoic acid during catalysis showed that Lewis acid-base site pairs of moderate strength mediate enolate formation steps via concerted interactions with the α-H atom and the enolate moiety at transition states. The resulting site-counts allow rigorous comparisons between theory and experiments and among catalysts on the basis of turnover rates and activation free energies. Theoretical treatments give barriers, kinetic isotope effects, and esterification/condensation ratios in excellent agreement with experiments and confirm the strong effects of reactant substituents at the α-C-atom and of surface structure on reactivity. Surfaces with Ti-O-Ti sites exhibiting intermediate acid-base strength and Ti-O distances, prevalent on anatase but not rutile TiO2, are required for facile α-C-H activation in reactants and reprotonation of the adsorbed intermediates that mediate condensation and esterification turnovers.
Rhodium-catalyzed direct aldol condensation of ketones: A facile synthesis of fused aromatic compounds
Terai, Hiroki,Takaya, Hikaru,Naota, Takeshi
, p. 1705 - 1708 (2006)
Cationic rhodium complex [Cp*Rh(η6-C6H 6)](BF4)2 (1) acts as an efficient catalyst for direct aldol condensation of ketones. The method can be applied to one-pot synthesis of fused aromatic compounds from cyclic ketones via sequential C-C bond formations.
Acetone condensation reaction on acid catalysts
Panov,Fripiat
, p. 188 - 197 (1998)
The condensation reaction of acetone on alumina and acid zeolites has been followed by FTIR. Under identical conditions, the reaction rate is faster on alumina, and the condensation goes beyond the formation of mesityl oxide. Zeolites without nonframework aluminum are poor catalysts. On HZSM-5 the reaction is about two orders of magnitude slower than on USY at 105°C. From these data, it appears that Lewis sites, even if they bound acetone less energetically than Bronsted sites, are responsible for the activation of the molecule. On alumina, the reaction would take place between gas phase acetone and acetone adsorbed on Lewis sites. On zeolites with nonframework aluminum and, thus, with Lewis sites, the reaction would involve acetone molecules adsorbed on Bronsted and Lewis sites, the activation occurring on the Lewis site.
ELECTROOXIDATIVE DESULFENYLATION OF MICHAEL-TYPE THIOL ADDUCTS OF α,β-UNSATURATED ESTERS, KETONES, AND NITRILES
Kimura, Makoto,Matsubara, Shinichi,Sawaki, Yasuhiko,Iwamura, Hiizu
, p. 4177 - 4178 (1986)
Michael adducts of ethanethiol with α,β-unsaturated esters ketones,and nitriles are conveniently desulfenylated under neutral conditions by an electrooxidation involving bromonium ion mediation.
Synthesis of Pyranocyclopentaindolines Representing the Western Sections of Janthitrem B, JBIR-137, and Shearinine G
Fresia, Marvin,Lindel, Thomas
supporting information, (2022/02/05)
The synthesis of the ABCD tetracyclic partial structures of the fungal indole diterpenes janthitrem B, JBIR-137, and shearinine G is reported. The route starts from 5-formylated indoline that is coupled to a dihydropyran moiety, followed by Prins cyclization. A diene was obtained that was oxygenated in a divergent manner. The hydroxylated tetracyclic western half of janthitrem B was obtained in eight steps and 10 % overall yield. We also share our experience with alternative approaches passing via alkynylated precursors. This includes the gold-catalyzed cycloisomerization of a 6-ethynyl-5-prenylindoline.
An active and stable multifunctional catalyst with defective UiO-66 as a support for Pd over the continuous catalytic conversion of acetone and hydrogen
Hu, Yingjie,Mei, Yuxin,Lin, Baining,Du, Xuhong,Xu, Fan,Xie, Huasheng,Wang, Kang,Zhou, Yonghua
, p. 48 - 56 (2021/02/09)
The one-pot synthesis of methyl isobutyl ketone (MIBK) and methyl isobutyl methanol (MIBC) from acetone and hydrogen is a typical cascade reaction comprised of aldol condensation-dehydration-hydrogenation. Pd loss and aggregation during long term operation are typical problems in industrial application. In this paper, an active and stable catalyst was achieved with defective UiO-66 as a support for Pd, which was synthesized with the ratio 15?:?1 of ZrOCl2·8H2O to ZrCl4as Zr-precursors. The resultant Pd catalyst remained active for at least 1000 h with a MIBK + MIBC selectivity of 84.87-93.09% and acetone conversion of 45.26-53.22% in a continuous trickle-bed reactor. Besides the increased Br?nsted acid amount generated by the defect sites was favorable for the activity, the cavity confinement in the UiO-66 (R= 15?:?1) structure also efficiently prevented Pd loss and aggregation during the long term run. The contrast of the characterization of the fresh and used Pd/UiO-66 (R= 15?:?1) indicated that the deactivation of the catalyst was attributed to carbonaceous accumulation on the catalyst surface, which could be easily regenerated by calcination. This work supplied a new alternative for the design and utilization of industrial catalysts for MIBK and MIBC synthesis.
