- CYCLO-ELIMINATION OF SILYL AND SULPHOXIDE GROUPS IN COMPETITION WITH THE CONVENTIONAL CYCLO-ELIMINATION OF SULPHOXIDES
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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.
- Fleming, Ian,Perry, David A.
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- Highly Stereoselective Synthesis of α,β-Unsaturated Ketones by CeCl3 Mediated Addition of Grignard Reagents to β-Enamino Ketones
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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.
- Bartoli, Giuseppe,Cimarelli, Cristina,Marcantoni, Enrico,Palmieri, Gianni,Petrini, Marino
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- Fluoride adducts of niobium(V): Activation reactions and alkene polymerizations
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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.
- Hayatifar, Mohammad,Marchetti, Fabio,Pampaloni, Guido,Patil, Yogesh,Raspolli Galletti, Anna Maria
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- Tricyanomethane and Its Ketenimine Tautomer: Generation from Different Precursors and Analysis in Solution, Argon Matrix, and as a Single Crystal
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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.
- Banert, Klaus,Chityala, Madhu,Hagedorn, Manfred,Beckers, Helmut,Stüker, Tony,Riedel, Sebastian,Rüffer, Tobias,Lang, Heinrich
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- INFRARED STUDY OF THE REACTIVITY OF ACETONE AND HEXACHLOROACETONE ADSORBED ON HAEMATITE
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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.
- Busca, Guido,Lorenzelli, Vincenzo
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- Acetone condensation over CaO—SnO2 catalyst
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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.
- Koklin,Hasyanova,Glukhov,Bogdan
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- Facile rearrangement of 3-oxoalkyl radicals is evident in low-temperature gas-phase oxidation of ketones
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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.
- Scheer, Adam M.,Welz, Oliver,Sasaki, Darryl Y.,Osborn, David L.,Taatjes, Craig A.
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- A convenient deoxygenation fo α,β-epoxy ketones to enones
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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.
- Dos Santos, Reginaldo B.,Brocksom, Timothy John,Brocksom, Ursula
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- 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
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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.
- Najmi, Sean,So, Jungseob,Stavitski, Eli,McDermott, William P.,Lyu, Yimeng,Burt, Sam P.,Hermans, Ive,Sholl, David S.,Sievers, Carsten
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- Silica Chloride (SiO2-Cl) and Trimethylsilyl Chloride (TMSCl) Promote Facile and Efficient Dehydration of Tertiary Alcohols
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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.
- Firouzabadi, Habib,Iranpoor, Naser,Hazarkhani, Hassan,Karimi, Babak
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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
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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.
- Wang, Shuai,Goulas, Konstantinos,Iglesia, Enrique
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- Rhodium-catalyzed direct aldol condensation of ketones: A facile synthesis of fused aromatic compounds
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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.
- Terai, Hiroki,Takaya, Hikaru,Naota, Takeshi
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- Acetone condensation reaction on acid catalysts
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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.
- Panov,Fripiat
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- Induction of chromosome aberrations in cultured human lymphocytes treated with ethoxyquin
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The chromosomal aberration test was employed to investigate the effect in vitro of a known antioxidant and food preservative, ethoxyquin (EQ, 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline) on human chromosomes. The studies were undertaken because there are no published in vitro data on genotoxicity of EQ in mammalian cells and there are many reports pointing out that it may be harmful to animals and human beings. Lymphocytes obtained from three healthy donors were incubated with EQ (0.01-0.5mM) both with and without metabolic activation. Stability studies performed by HPLC analysis showed that EQ was stable under the conditions of the lymphocyte cultures. The results of the chromosome aberration assay showed that EQ induces chromosome aberrations: gaps and breaks as well as dicentrics and atypical translocation chromosomes.
- Blaszczyk,Osiecka,Skolimowski
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- ELECTROOXIDATIVE DESULFENYLATION OF MICHAEL-TYPE THIOL ADDUCTS OF α,β-UNSATURATED ESTERS, KETONES, AND NITRILES
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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.
- Kimura, Makoto,Matsubara, Shinichi,Sawaki, Yasuhiko,Iwamura, Hiizu
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- Asymmetric catalysis at the mesoscale: Gold nanoclusters embedded in chiral self-assembled monolayer as heterogeneous catalyst for asymmetric reactions
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Research to develop highly versatile, chiral, heterogeneous catalysts for asymmetric organic transformations, without quenching the catalytic reactivity, has met with limited success. While chiral supramolecular structures, connected by weak bonds, are highly active for homogeneous asymmetric catalysis, their application in heterogeneous catalysis is rare. In this work, asymmetric catalyst was prepared by encapsulating metallic nanoclusters in chiral self-assembled monolayer (SAM), immobilized on mesoporous SiO2 support. Using olefin cyclopropanation as an example, it was demonstrated that by controlling the SAM properties, asymmetric reactions can be catalyzed by Au clusters embedded in chiral SAM. Up to 50% enantioselectivity with high diastereoselectivity were obtained while employing Au nanoclusters coated with SAM peptides as heterogeneous catalyst for the formation of cyclopropane- containing products. Spectroscopic measurements correlated the improved enantioselectivity with the formation of a hydrogen-bonding network in the chiral SAM. These results demonstrate the synergetic effect of the catalytically active metallic sites and the surrounding chiral SAM for the formation of a mesoscale enantioselective catalyst.
- Gross, Elad,Liu, Jack H.,Alayoglu, Selim,Marcus, Matthew A.,Fakra, Sirine C.,Toste, F. Dean,Somorjai, Gabor A.
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- Synthesis of Pyranocyclopentaindolines Representing the Western Sections of Janthitrem B, JBIR-137, and Shearinine G
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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.
- Fresia, Marvin,Lindel, Thomas
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supporting information
(2022/02/05)
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- Cassis and Green Tea: Spontaneous Release of Natural Aroma Compounds from β-Alkylthioalkanones
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In depth headspace analysis of the slow degradation of β-alkylthioalkanones in ambient air led to the discovery of a novel δ-cleavage pathway, by which β-mercaptoketones are released. Since β-mercaptoketones are potent natural aroma compounds occurring in many fruits, herbs and flowers, the discovery of an enzyme-independent molecular precursor for this class of high-impact molecules is of practical importance. Moreover, the formation of β-diketones and aldehydes by concomitant oxidation at the α-sulfur-position enhances the versatility of this class of aroma precursors. A mechanistic model is proposed which suggests that the oxidative degradation occurs through a novel Pummerer-type rearrangement of initially formed persulfoxides.
- B?ttig, Sarah,Bochet, Christian G.,Egger, Timothy,Flachsmann, Felix,Gey, Olga
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- An active and stable multifunctional catalyst with defective UiO-66 as a support for Pd over the continuous catalytic conversion of acetone and hydrogen
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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.
- Hu, Yingjie,Mei, Yuxin,Lin, Baining,Du, Xuhong,Xu, Fan,Xie, Huasheng,Wang, Kang,Zhou, Yonghua
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- Method for preparing triacetone amine
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An improved method is used for preparing triacetone amine while recycling the by-products. This involves treating the crude product from triacetone amine preparation, which leads to an increase in the content of compounds which react readily with ammonia. This method enables efficient recycling of the by-products formed in the synthesis of triacetone amine.
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Paragraph 0133-0144
(2020/07/05)
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- Ketalization of ketones to 1,3-dioxolanes and concurring self-aldolization catalyzed by an amorphous, hydrophilic SiO2-SO3H catalyst under microwave irradiation
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The amorphous, mesoporous SiO2-SO3H catalyst with a surface area of 115 m2 g-1 and 1.32 mmol H+ per g was very efficient for the protonation of ketones on a 10percent (m/m) basis, and the catalyst-bound intermediates can be trapped by polyalcohols to produce ketals in high yields or suffer aldol condensations within minutes under low-power microwave irradiation. The same catalyst can easily reverse the ketalization reaction. Printed in Brazil-
- Barbosa, Sandro L.,Ottone, Myrlene,De Almeida, Mainara T.,Lage, Guilherme L.C.,Almeida, Melina A.R.,Nelson, David Lee,Dos Santos, Wallans T.P.,Clososki, Giuliano C.,Lopes, Norberto P.,Klein, Stanlei I.,Zanatta, Lucas D.
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p. 1663 - 1671
(2018/06/29)
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- Fabrication of Pd-based metal-acid-alkali multifunctional catalysts for one-pot synthesis of MIBK
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The one-pot synthesis of methyl isobutyl ketone (MIBK) from acetone using multifunctional catalysts is an important sustainable organic synthesis method with high atom and energy efficiency. Herein. we report a series of Pd supported on mixed metal oxide (MMO) catalysts with controllable acidic/basic/metallic sites on the surface. We study the relationship between the nature, synergy, and proximity of active sites and the catalytic performance of the multifunctional catalyst in the tandem reaction, in detail. In the existence of Lewis acid and base sites, the catalysts with medium-strength acidic/basic sites show preferred activity and/or MIBK selectivity. For multifunctional catalysts, the catalytic properties are more than just a collection of active sites, and the Pd/Mg3Al-MMO catalyst possessing 0.1% Pd loading and ~0.4 acid/base molar ratio exhibits the optimal 42.1% acetone conversion and 37.2% MIBK yield, which is among the best reported so far for this tandem reaction under similar conditions. Moreover, the proximity test indicates that the intimate distance between acidic/basic/metallic sites can greatly shorten the diffusion time of the intermediate species from each active site, leading to an enhancement in the catalytic performance.
- Ma, Rui,Li, Yunpeng,Wu, Guandong,He, Yufei,Feng, Junting,Zhao, Yingying,Li, Dianqing
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p. 1384 - 1394
(2018/07/14)
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- Preparation method of mesityl oxide
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The present invention discloses a preparation method of mesityl oxide. The method comprises the steps of adopting acetone as a raw material, putting a solid catalyst in a fixed bed catalytic condensation reactor, and subjecting acetone to condensation-dehydration reaction in the bed layer of the catalytic condensation reactor to generate mesityl oxide and water; subjecting the above products to distillation; adopting the magnesium-aluminum hydrotalcite as a precursor of the solid catalyst and the modified nano-zeolite powder as a carrier of the solid catalyst, wherein the mass ratio of the precursor to the carrier is 25-45%; uniformly mixing up the precursor and the carrier, and calcinating the obtained mixture at 500-700 DEG C for 2-4 hours. The molar ratio of magnesium element to aluminum element in the magnesium-aluminum hydrotalcite is 2-3:1. The preparation method of the magnesium-aluminum hydrotalcite comprises the steps of mixing up the magnesium salt and the aluminum salt, and dissolving the magnesium salt and the aluminum salt in deionized water to prepare a mixed salt solution; dissolving a precipitating agent in deionized water to obtain an alkali solution; adding the resulted mixed salt solution and the alkaline solution into a reaction container in the parallel flow manner, subjecting the obtained product to reaction at 40-80 DEG C for 30-60 minutes at the pH value of 9-11, standing the obtained product for 8-16 hours, washing the obtained precipitate to be neutral, and drying the product to obtain the magnesium-aluminum hydrotalcite.
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Paragraph 0016; 0017; 0018; 0019
(2017/02/24)
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- SYNTHESIS OF DIACETONE ALCOHOL AND MESITYL OXIDE
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Processes for synthesizing diacetone alcohol from acetone are provided. An exemplary process includes contacting acetone with a heterogeneous catalyst at a temperature of less than 100 °C, to provide diacetone alcohol. The heterogeneous catalyst can include molecular sieves. Processes for synthesizing mesityl oxide from acetone are also provided.
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Paragraph 0046
(2016/02/26)
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- A method of preparation of ethoxy quinoline (by machine translation)
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The invention relates to a method for preparing ethoxy quinoline and belongs to the field of fodder and food. The preparation of the ethoxy quinoline is divided into two steps, namely the preparation of midbody 4-methyl-3-penten-2-ketone and the preparation of a finished product ethoxy quinoline. The method comprises the steps that firstly acetone is transformed into the midbody 4-methyl-3-penten-2-ketone, the potential safety hazards to an operator due to the fact that in the reaction process, the acetone is not reacted completely and volatilized under heating are prevented, and in the transformation process of the 4-methyl-3-penten-2-ketone, by using a catalyst, namely 4%-6% of Mg2+mesoporous molecular sieve, the high-purity 4-methyl-3-penten-2-ketone midbody can be obtained; methylbenzene serves as solvent as well as a water-carrying agent, 'azeotropy' is conducted through the methylbenzene and water generated in reaction, water can be separated, so that the reaction is conducted toward the positive reaction direction, meanwhile, by adding the methylbenzene solvent, an 'inert' solvent gas environment is formed inside a reaction tank, and oxidation of materials is avoided; by means of the combined action of the methylbenzene and toluenesulfonic acid, the produced ethoxy quinoline can reach the standards of feed grade ethoxy quinoline.
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Paragraph 0024-0026
(2017/05/12)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
- Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
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p. 420 - 430
(2015/12/31)
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- An acelylenically of a diene compound and/or method of manufacturing
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Provided is a novel method for producing a compound having acetylene bonds and/or a diene. The method for producing a compound having acetylene bonds and/or a diene is characterized in that at least one selected from the group consisting of ketone compound (I), ketone compound (II), aldehyde compound (III), aldehyde compound (IV), and aldehyde compound (V) is dehydrated in the presence of a catalyst wherein a carrier containing silica supports at least one selected from the group consisting of compounds containing group 1 metal elements, compounds containing group 2 metal elements, group 1 metal elements, and group 2 metal elements.
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Paragraph 0412-0418
(2017/03/28)
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- L-Proline and thiourea co-catalyzed condensation of acetone
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Amino acid and primary amine/amide co-catalyzed acetone condensation was investigated. It was found that L-proline had overwhelming catalytic activity over other amino acids as well as the analogues with similar structures. Surprisingly, thiourea, a very cheap and stable chemical, was found to be the favorable co-catalyst. Co-catalyzed by the recyclable L-proline and thiourea, condensation of acetone led to the useful products mesityl oxide (MO), diacetone alcohol (DAA) and isophorone (IP) in the excellent 96.3% total selectivity.
- Xu, Lin,Wang, Fang,Huang, Jiejun,Yang, Chenggen,Yu, Lei,Fan, Yining
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p. 4076 - 4080
(2016/07/06)
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- Towards understanding the hydrodeoxygenation pathways of furfural-acetone aldol condensation products over supported Pt catalysts
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Aiming at the valorisation of furfural-derived compounds, the hydrodeoxygenation of furfural-acetone condensation products has been studied using supported platinum catalysts. The influence of the catalytic properties of different supports, such as SiO2, Al2O3, TiO2, hydrotalcite (HTC), Beta zeolite, Al-SBA-15 and WO3-ZrO2, was evaluated in a batch reactor for 480 min at 200 °C and 50 bar of H2. The used feed consisted of a mixture of furfural-acetone adducts (C8-C19), obtained in previous experiments using a continuous flow reactor and hydrotalcite as a catalyst. Except for Pt/SiO2, all catalysts showed high conversion of the reactants, especially due to the hydrogenation of all the aliphatic CC bonds. However, the extent of further hydrogenation (furan CC and ketone CO bonds) was limited, particularly when HTC and Al2O3 were used as supports. The higher accessibility of Pt/TiO2 and the smaller Pt particle size shown by Pt/Al-SBA-15, Pt/WO3-ZrO2 and Pt/Beta in comparison with the other catalysts led to an improvement in the hydrogenation of furanic and ketonic groups, likely due to lower adsorption constraints. The higher acid character of the latter group of catalysts promotes dehydration and ring opening steps, thus enhancing the selectivity towards linear alcohols. Likewise, a significant increase in the extent of aldol condensation reactions was also observed with these catalysts, yielding longer carbon chain compounds. Based on this study, a reaction scheme for the transformation of 4-(2-furyl)-3-buten-2-one (C8) into octane has been proposed in order to establish a valuable correlation between the main conversion pathways and the catalytic properties of the employed heterogeneous catalyst, thus contributing to further development of efficient deoxygenation catalysts.
- Ramos,Ti?ler,Kikhtyanin,Kubi?ka
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p. 1829 - 1841
(2016/04/05)
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- Novel Benzo[a]quinolizidine Analogs Induce Cancer Cell Death through Paraptosis and Apoptosis
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Paraptosis is nonapoptotic cell death characterized by massive endoplasmic reticulum (ER)- or mitochondria-derived vacuoles. Induction of paraptosis offers significant advantages for the treatment of chemotherapy-resistant tumors compared with anticancer drugs that rely on apoptosis. Because some natural alkaloids induce paraptotic cell death, a novel series of benzo[a]quinolizidine derivatives were synthesized, and their antiproliferative activity and ability to induce cytoplasmic vacuolation were analyzed. Structural optimization led to the identification of the potent compound 22b, which inhibited cancer cell proliferation in vitro and in vivo and profoundly facilitated paraptosis-like cell death and induced caspase-dependent apoptosis. Further investigation revealed that 22b-mediated vacuolation originated from persistent ER stress and upregulation of LC3B. Paraptosis induced by benzo[a]quinolizidine derivatives thus represents an alternative strategy for cancer chemotherapy.
- Zheng, Hongbo,Dong, Yiwen,Li, Lin,Sun, Bin,Liu, Lei,Yuan, Huiqing,Lou, Hongxiang
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supporting information
p. 5063 - 5076
(2016/06/13)
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- A 2-heptanone synthetic method
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The invention discloses a chemical synthetic method, specifically a method for synthesizing 2-heptanone by using acetone and butyraldehyde as raw materials. According to the invention, acetone and butyraldehyde which used as raw materials undergo a cross aldol condensation reaction under catalysis of solid base, and reaction products further undergo dehydration and catalytic hydrogenation so as to prepare 2-heptanone. The invention has advantages as follows: technological process is shortened by the technology; generation of an acid-containing waste liquid is avoided; generation of by-products is minimized; investment in equipment is reduced; and production costs of the product are decreased.
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Paragraph 0048-0051
(2017/01/26)
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- Studies on the low-temp oxidation of coal containing organic sulfur and the corresponding model compounds
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This paper selects two typical compounds containing organic sulfur as model compounds. Then, by analyzing the chromatograms of gaseous low-temp oxidation products and GC/MS of the extractable matter of the oxidation residue, we summarizing the mechanism of low-temp sulfur model compound oxidation. The results show that between 30 °C to 80 °C, the interaction between diphenyl sulfide and oxygen is mainly one of physical adsorption. After 80 °C, chemical adsorption and chemical reactions begin. The main reaction mechanism in the low-temp oxidation of the model compound diphenyl sulfide is diphenyl sulfide generates diphenyl sulfoxide, and then this sulfoxide is further oxidized to diphenyl sulphone. A small amount of free radicals is generated in the process. The model compound cysteine behaves differently from diphenyl sulfide. The main reaction low-temp oxidation mechanism involves the thiol being oxidized into a disulphide and finally evolving to sulfonic acid, along with SO2 being released at 130 °C and also a small amount of free radicals. We also conducted an experiment on coal from Xingcheng using X-ray photoelectron spectroscopy (XPS). The results show that the major forms of organic sulfur in the original coal sample are thiophene and sulfone. Therefore, it can be inferred that there is none or little mercaptan and thiophenol in the original coal. After low-temp oxidation, the form of organic sulfur changes. The sulfide sulfur is oxidized to the sulfoxide, and then the sulfoxide is further oxidized to a sulfone, and these steps can be easily carried out under experimental conditions. What's more, the results illustrate that oxidation promotes sulfur element enrichment on the surface of coal.
- Zhang, Lanjun,Li, Zenghua,Li, Jinhu,Zhou, Yinbo,Yang, Yongliang,Tang, Yibo,McPhee, Derek J.
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p. 22241 - 22256
(2016/01/25)
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- Bismuth-substituted "sandwich" type polyoxometalate catalyst for activation of peroxide: Umpolung of the peroxo intermediate and change of chemoselectivity
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The epoxidation of alkenes with peroxides by WVI, MoVI, VV, and TiIV compounds is well established, and it is well accepted that the active intermediate peroxo species are electrophilic toward nucleophilic substrates. Polyoxotungstates, for example, those of the "sandwich" structure, [WZn(TM-L)2(ZnW9O34)2]q- in which TM = transition metal and L = H2O, have in the past been found to be excellent epoxidation catalysts. It has now been found that substituting the Lewis basic BiIII into the terminal position of the "sandwich" polyoxometalate structure to yield [Zn2BiIII2(ZnW9O34)2]14- leads to an apparent umpolung of the peroxo species and formation of a nucleophilic peroxo intermediate. There are two lines of evidence that support the formation of a reactive nucleophilic peroxo intermediate: (1) More electrophilic sulfoxides are more reactive than more nucleophilic sulfides, and (2) nonfunctionalized aliphatic alkenes and dienes showed ene type reactivity rather than epoxidation pointing toward "dark" formation of singlet oxygen from the nucleophilic intermediate peroxo species. Allylic alcohols reacted much faster than alkenes but showed chemoselectivity toward C-H bond activation of the alcohol and formation of aldehydes or ketones rather than epoxidation. This explained via alkoxide formation at the BiIII center followed by oxidative β-elimination.
- Amanchi, Srinivasa Rao,Khenkin, Alexander M.,Diskin-Posner, Yael,Neumann, Ronny
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p. 3336 - 3341
(2015/06/16)
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- Catalyst for aldol condensation
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In one embodiment, the invention is to a catalyst composition comprising lime and cement. Preferably, the catalyst composition comprises the lime and the cement in a weight ratio of at least 3.5:1 respectively.
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Page/Page column 9-10
(2015/12/25)
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- TWO-STEP SYSTEM AND METHOD FOR THE PRODUCTION OF METHYL ISOBUTYL KETONE
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Embodiments of the present invention describe systems and methods for production of methyl isobutyl ketone (MIBK) from acetone and hydrogen in a two-step process. The composition of the product stream from the first reaction step is adjusted so that the resulting stream can undergo a favorable liquid-liquid separation in a decanter, and an MO rich product stream can be recovered. The composition of the feed to the decanter is controlled by choosing the number of reactor stages for the first reaction step and their operating temperatures, and/or by recycling some MIBK to the decanter feed. The method does not require a substantially complete conversion of acetone in the first reaction step, nor does it require a removal of DAA from the product of the first reaction step by separation.
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Paragraph 0045
(2015/02/02)
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- HYDROLYSIS OF THE RESIDUES OBTAINED IN THE PRODUCTION OF ISOPHORONE TO RECOVER ISOPHORONE AND ACETONE
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A process for preparing isophorone (3,5,5-trimethyl-2-cyclohexen-1-one) is provided wherein distillation vapors from the work-up of product fractions are recycled to earlier stages of operation of the process.
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Paragraph 0033
(2015/02/25)
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- An efficient bifunctional catalyst of TiO2 coating and supported Pd on cordierite for one-pot synthesis of MIBK from acetone
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We report here an efficient bifunctional catalyst of TiO2 coating and supported Pd on cordierite (T500/Cor&Pd/Cor) for one-pot synthesis of MIBK from acetone. The obtained 75% MIBK selectivity at 60% acetone conversion was the best performance ever reported for metal oxide based catalyst, without obvious deactivation for at least 12 h on stream. The superior performance of T500/Cor&Pd/Cor could be attributed to the dominant base sites and moderate acid sites on TiO2 coating caused by the nanoscale anatase crystallite, and its combination style of being physically mixed with Pd.
- Zhang, Shoude,Wu, Pengcheng,Yang, Lequn,Zhou, Yonghua,Zhong, Hong
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-
- Effect of Alkali Treatment of HY Zeolite on Continuous Synthesis of Triacetonamine
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The continuous synthesis of triacetonamine from acetone and ammonia over HY was realized. Meanwhile, alkali-treated HY with different structure and acidities were prepared and examined. The results indicated that the acid sites, especially Br?nsted acid sites, played a vital role on the selectivity of triacetonamine and the conversion of acetone. It was further confirmed by X-ray diffraction (XRD), N2 adsorption and desorption experiments, IR spectra of adsorbed pyridine, and NH3 temperature-programmed desorption. Meanwhile, the generation mechanisms of triacetonamine and impurities were speculated.
- Tian, Jun,Chen, Ligong,Zhang, Chao,Yan, Xilong,Li, Yang
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p. 1377 - 1381
(2015/02/19)
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- Design and application of the recyclable poly(l-proline-co-piperidine) catalyst for the synthesis of mesityl oxide from acetone
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Unexpectedly, l-proline/piperidine was found to be a better recyclable catalyst system than l-proline or piperidine alone in the condensation of acetone to prepare mesityl oxide (MO), an important intermediate in the chemical industry. Binding the catalyst system onto polymer resin enhanced the MO selectivity and reduced the catalyst loss. The mechanism of the bi-component catalyst system was also studied through control reactions, as well as by dynamic calculations. The MO selectivity could reach 74.4% and its isolated yield could reach 73.9%, based on the consumed acetone. Although the result does not immediately meet the requirement of industrial production, this study provides a novel organocatalyst system, which might offer a potential alternative to traditional inorganic catalysts that can be used under mild and neutral conditions.
- Xu, Lin,Huang, Jiejun,Liu, Yubing,Wang, Yining,Xu, Bolian,Ding, Kehong,Ding, Yuanhua,Xu, Qing,Yu, Lei,Fan, Yining
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p. 42178 - 42185
(2015/05/27)
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- IMPROVEMENTS IN OR RELATING TO ORGANIC COMPOUNDS
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A process of converting a carbon-carbon multiple bond to a cyclopropane ring, comprising the addition of a N-alkyl-N-nitroso compound to a mixture of alkene precursor, aqueous base and Pd(II)-catalyst, with the N-alkyl-N-nitroso compound obtained directly from an alkyl amine derivative, NaNO2 and an acid via phase separation of the N-alkyl-N-nitroso compound from the aqueous phase.
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Page/Page column 21
(2015/05/06)
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- Cascade reactions for the continuous and selective production of isobutene from bioderived acetic acid over zinc-zirconia catalysts
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Bio-oil (obtained from biomass fast pyrolysis) contains a high concentration of acetic acid, which causes problems related to its storage and handling. Acetic acid was upgraded directly to isobutene over a ZnxZryOz binary metal oxide. The reaction proceeds via a three-step cascade involving ketonization, aldol condensation, and C-C hydrolytic bond cleavage reactions, which was corroborated by isotopic labeling studies. Separately, ZnO and ZrO2 are incapable of producing isobutene from either acetic acid or acetone. In contrast, under optimal conditions, a Zn2Zr8Oz catalyst generates a ca. 50% isobutene yield, which corresponds to 75% of the theoretical maximum. Spectroscopic investigations revealed that a balanced concentration of acid and base sites is required to maximize isobutene yields.
- Crisci, Anthony J.,Dou, Herui,Prasomsri, Teerawit,Romn-Leshkov, Yuriy
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p. 4196 - 4200
(2015/02/19)
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- A new peroxo-route for the synthesis of Mg-Zr mixed oxides catalysts: Application in the gas phase acetone self-condensation
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We propose in this manuscript a new peroxo-mediated procedure for preparing magnesia-zirconia mixed oxides, with Mg/Zr molar ratio between 1 and 3, with enhanced distribution of basic sites. The mixed magnesia-zirconia oxides have been prepared from the gelled complex by Pechini-type method. The MgO-ZrO 2 materials have been characterized and used as catalysts for acetone aldol condensation. The proposed preparation method provides a high degree of molecular homogeneity and favours the formation of magnesia-stabilized zirconia phase. Acetone gas-phase self-condensation was carried out over these catalysts as model reaction requiring the presence of basic sites. The condensation yields diacetone alcohol and mesityl oxide as mean C6 products, and phorones, isophorones and mesitylene as C9 products. In comparison to Mg-Zr oxide prepared by co-precipitation, these new materials present better conversions and higher selectivity to linear dimers and trimers (as mesitylene), whereas the selectivity for isophorones is significantly lower.
- Krivtsov, Igor,Faba, Laura,Díaz, Eva,Ordó?ez, Salvador,Avdin, Viacheslav,Khainakov, Sergei,Garcia, Jose R.
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- Continuous synthesis of triacetonamine over sulfonic acid-functionalized mesoporous silicas
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The continuous synthesis of triacetonamine from acetone and ammonia was realized over sulfonic acid-functionalized mesoporous silicas. These catalysts were characterized by TG, XPS, BET, elemental analysis and acid-base titration. The results indicated th
- Tian, Jun,Chen, Ligong,Zhang, Chao,Yan, Xilong,Li, Yang
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p. 17860 - 17865
(2014/05/06)
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- Ru-C-ZnO composite catalysts for the synthesis of methyl isobutyl ketone via single step gas phase acetone self-condensation
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Ruthenium/activated charcoal (Ru-C) was modified by a solid-solid interaction method with synthesized nano-zinc oxide (n-ZnO). Three different ratios of Ru-C:n-ZnO (1:2, 1:1 and 3:2) were used to prepare Ru-C-ZnO composite catalysts. These were used in the gas-phase, one-step self-condensation of acetone to methyl isobutyl ketone (MIBK). The composite catalyst (1:1 ratio) contained 2.5 wt% Ru showed superior conversion of acetone and selectivity for MIBK. Furthermore, this catalyst showed good consistency for MIBK formation for 100 h without any deactivation. Characterization of the catalysts revealed that balanced hydrogenation and acid-base functional character is crucial to obtain high catalytic performance.
- Bagabas, Abdulaziz A.,Mokhtar, Mohamed,Akhmedov, Vagif M.,Narasimharao, Katabathini,Basahel, Sulaiman N.,Al-Rabiah, Abdulrahman
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p. 1278 - 1288
(2014/07/21)
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- A METHOD FOR THE PREPARATION OF DIAZOALKANES
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The present invention relates to a method of forming diazoalkanes. One aspect of the present invention provides a method for the production of a N-alkyl-N-nitroso compound from a starting material, comprising the use of a tribasic acid to acidify an amine. A second aspect of the present invention provides a method for the production of a diazoalkane, comprising reacting a N-alkyl-N-nitroso compound with a base and a phase transfer catalyst, wherein no organic solvent is used,
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Page/Page column 16
(2013/08/15)
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- Synthesis of β-sulfanyl ketones via a tandem rearrangement-conjugate addition reaction catalyzed by a Re(V)-oxo complex
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A method for synthesizing β-sulfanyl ketones via a tandem rearrangement and conjugate addition reaction has been developed. This methodology provides access to a range of β-sulfanyl ketones through the rearrangement of propargyl alcohols to the corresponding enones followed by the conjugate addition of unactivated thiols. The one-pot, tandem transformation is catalyzed by ReOCl3(OPPh3)(S(CH3)2) affording aryl and alkyl β-sulfanyl ketones in good to excellent yield.
- Garst, Alyson E.,Badiceanu, Alexandra D.,Nolin, Kristine A.
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supporting information
p. 459 - 461
(2013/02/23)
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- Acetone condensation over sulfated zirconia catalysts
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The aldol condensation reaction over sulfated zirconia led to the production of diacetone alcohol, which was further dehydrated forming mesityl oxide. The sulfated zirconia was obtained from zirconium acetate ethane sulfonate as a single source precursor. Oxides were obtained by calcinations of the precursors at 550-650 C, while the self-condensation reaction of acetone was carried out at 150 C. The precursor and the produced oxides were characterized using various characterization techniques. The precursors were synthesized with different acetate to ethane sulfonate ratio, ranging from 1 to 3. The major products obtained from the condensation reaction over the resulted oxide were mesityl oxide, mesitylene isophorone, naphthalene, and pentamers. The selectivity of mesityl oxide was approximately 100 % at the initial time-on-stream.
- Al-Hazmi, Mohammed H.,Choi, Yongman,Apblett, Allen W.
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p. 705 - 716
(2013/07/26)
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- Synthesis of 10-amino-9-aryl-2,3,4,5,6,7,9,10-octahydroacridine- 1,8-dione derivatives
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A series of novel 10-amino-9-aryl-2,3,4,5,6,7,9,10-octahydroacridine-1,8- dione derivatives 4 were synthesized by hydrazine or phenylhydrazine and 9-aryl-1,8-dioxo-2,3,4,5,6,7,9-heptahydroxanthene derivatives 3, which were prepared by 5-substituted-1,3-cyclohexanedione 1 and aromatic aldehydes 2 in the presence of concentrated H2SO4 as a catalyst in water. The structures of all compounds were characterized by IR, MS, 1H-NMR, and elemental analysis, and the title compounds possess good fluorescence properties..
- Han, Guang-Fan,Cui, Bin,Chen, Li-Zhuang,Hu, Xiao-Lei
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scheme or table
p. 195 - 199
(2012/04/17)
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- Synthesizing and utilizing novel nano crystalline zinc chromate supported nano palladium catalyst
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Several metal-supported catalyst compositions based on nano-crystalline zinc oxide were synthesized and characterized by X-ray powder diffraction (XRD), Carbon dioxide temperature programmed desorption (CO2 TPD), and nitrogen adsorption at ?196° C. The Pd-supported nano-ZnO mixed with different oxides such as Cr2O3, CrO3, MgO, and γ-Al2O3 showed high catalytic activity in acetone condensation in gas-phase process under hydrogen flow. This reaction involves the base-acid coupling of acetone to form mesityl oxide, followed by its hydrogenation to methyl isobutyl ketone (MIBK). The novel catalyst 1% wt. n-Pd/n-ZnCr2O4 was utilized during gas-phase reaction during production of MIBK. MIBK selectivity was 70-72% at 66-77% acetone conversion at 300-350° C. Diisobutyl ketone (DIBK) was the main by-product, with a total MIBK+DIBK selectivity up to 88%. The prepared catalysts showed stable activity and may be used repeatedly and for a longer period of time.
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Page/Page column 6-7
(2011/06/23)
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- LOW PRESSURE ONE-STEP GAS-PHASE PROCESS FOR PRODUCTION OF METHYL ISOBUTYL KETONE
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A low-pressure one-step gas-phase process for the production and recovery of methyl isobutyl ketone (MIBK) is disclosed. One-step gas-phase synthesis of MIBK from acetone and hydrogen over nano-Pd/nano-ZnCr2O4 catalyst at atmospheric pressure is used as an example. The said process is designed to recover the additional heat associated with the reactor effluent via heating acetone feed and recycle (mixed acetone) before entering the reactor. A compressor is introduced to the gas-phase process to increase slightly the reactor effluent pressure before this effluent is cooled and fed to a flash drum. The compressed reactor effluent is used to preheat hydrogen feed and recycle (mixed hydrogen) before entering the reactor. The separation scheme of low-pressure one-step gas-phase process comprises of several distillation columns used for MIBK separation and purification.
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Page/Page column 6
(2011/10/12)
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- Multifunctional catalysis by Pd@MIL-101: One-step synthesis of methyl isobutyl ketone over palladium nanoparticles deposited on a metal-organic framework
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Palladium nanoparticles deposited on a chromium terephthalate MIL-101 is a highly efficient multifunctional catalyst for the one-step synthesis of methyl isobutyl ketone, with significantly higher activity than palladium on traditional materials, such as metal oxides and zeolites.
- Pan, Yingyi,Yuan, Bizhen,Li, Yingwei,He, Dehua
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supporting information; experimental part
p. 2280 - 2282
(2010/07/09)
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- Green synthesis of 1,8-dioxo-octahydroxanthene derivatives using catalytic amount of H2SO4 in water
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An green and convenient approach to the synthesis of 3,6,9-aryl-1,8-dioxo- 1,2,3,4,5,6,7,8-octahydroxanthene derivatives from appropriate aromatic aldehydes and 5-aryl-1,3-cyclo-hexanedione in the presence of two drops of concentrated H2SO4 as a catalyst in water is described. This method provides several advantages such as environmental friendliness, low cost, excellent yields, and simple workup procedure. Copyright
- Wang, Rui-Hua,Cui, Bin,Zhang, Wen-Tao,Han, Guang-Fan
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scheme or table
p. 1867 - 1872
(2010/07/02)
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- Cr, Zr-incorporated hydrotalcites and their application in the synthesis of isophorone
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Cr3+ and Zr4+ cation-incorporated hydrotalcites (HTs) were prepared by coprecipitation method. Corresponding mixed oxide were obtained by the thermal decomposition of HTs at 773 K for 8 h and applied in the synthesis of isophorone (IP) from acetone. From the characteristic results, both Cr3+ and Zr4+ were introduced into the lattice of hydrotalcite producing the more disordered HT structures. Compared with Mg-Al mixed oxide, Cr and Zr modified mixed oxide demonstrated more amount of basic sites and stronger base strength, which were responsible for the improvement of catalytic activity. As a result, both of the modified mixed oxide exhibited IP selectivity of more than 70% under atmospheric pressure.
- Liu, Yanxia,Sun, Kunpeng,Ma, Haowen,Xu, Xianlun,Wang, Xiaolai
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experimental part
p. 880 - 883
(2010/11/04)
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- A systematic study on the activation of simple polyethers by MoCl 5 and WCl6
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MoCl5, 1a, and WCl6, 1b, activate 1,3-dioxolane at room temperature in chlorinated solvents: the compound [MoOCl 3{OC(H)OCH2CH2Cl}]2, 2, has been isolated from MoCl5/dioxolane. The mixed oxo-chloro species WOCl 4, 1c, reacts with 1,3-dioxolane, selectively giving the coordination adduct WOCl4(κ1-C3H6O 2), 3. Dimethoxymethane, CH2(OMe)2, undergoes activation including C-H bond cleavage when reacted with 1a to give the molybdenum complexes [MoOCl3{OC(H)OMe}]2, 4, and Mo 2Cl5(OMe)5, 5. The reactions of 1b with CH 2(OR)2 (R = Me, Et) proceed via O-abstraction with formation of the oxo-derivatives WOCl4[O(R)CH2Cl] (R = Me, 6a; R = Et, 6b) in admixture with equimolar amounts of RCl. The reactions of 1a,b with CMe2(OMe)2 lead to mesityl oxide, MeC(O)CHC(Me)2. A series of simple diethers of general formula ROCH2(CHR′)OR′′ are activated by 1a,b in CDCl 3, usually via cleavage of C-O bonds at high temperature. The complex WCl5(OCH2CH2OMe), 7, has been detected in solution as an intermediate species in the course of the degradation of 1,2-dimethoxyethane (dme) by 1b. The activation of CH(OMe)3 by 1 is limited to C-O bonds and selectively gives methyl chloride and methylformate, which has been found coordinated in WOCl4[OC(H)OMe], 8. The organic fragments produced in the reactions have been detected by GC-MS and NMR analyses, upon hydrolysis of the reaction mixtures. Compounds 2 and 5, which have had their molecular structures ascertained by X-ray diffraction, represent rare examples of crystallographically-characterized dinuclear Mo(v) species containing both halides and oxygen ligands.
- Dolci, Sara,Marchetti, Fabio,Pampaloni, Guido,Zacchini, Stefano
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experimental part
p. 5367 - 5376
(2010/08/04)
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- Synthesis of methyl acetoacetate from acetone and dimethyl carbonate with alkali-promoted MgO catalysts
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The synthesis of methyl acetoacetate (MAA) by methoxycarbonylation of acetone with dimethyl carbonate (DMC) was carried out in the presence of MgO and alkali-promoted MgO catalysts. From among Li, Na, K, and Cs, potassium was found to be the most effective promoter to improve the activity of MgO. The effect of K/MgO with variable content of K was also investigated, and the individual catalysts were characterised by the XRD, BET, SEM, CO2-TPD, and in situ CO2 IR techniques. The results showed that the addition of a small amount of K (1.97 mass %) could promote MAA formation, but a higher K loading caused a decrease in the yield of MAA, which might result from particle agglomeration and the presence of stable potassium carbonates. In situ FTIR experiments of co-adsorbed reactants indicated that the reaction probably proceeded via abstraction of Hα from acetone by base sites.
- Wu, Dudu,Chen, Zhi
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experimental part
p. 758 - 766
(2011/11/29)
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- NOVEL CATALYST FOR ALDOL CONDENSATION REACTIONS
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The present invention presents catalytic systems for aldol condensation reactions, comprising the step of reacting at least one aldehyde or one ketone starting material in the presence of an inorganic ammonium salt, or an aqueous or organic solution prepared from such salt. The efficiency of the catalytic system of the present invention is comparable to those of the classical strong acid and strong base catalysts.
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Page/Page column 9-11
(2009/05/29)
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- Effect of additives on chemoselectivity and diastereoselectivity in the catalytic epoxidation of chiral allylic alcohols with hydrogen peroxide and binuclear manganese complexes
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The catalytic oxidations of chiral allylic alcohols 2 by manganese complexes of the cyclic triamine 1,4,7-trimethyl-1,4,7-triazacyclononane (tmtacn) 1 and hydrogen peroxide as oxygen donor in the presence of co-catalyst are investigated to understand the
- Kilic, Hamdullah,Adam, Waldemar,Alsters, Paul L.
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experimental part
p. 1135 - 1140
(2009/07/04)
-
- A facile procedure for acetalization of aldehydes and ketones catalyzed by cerium(III) trifluoromethanesulfonate
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Aldehydes and ketones are readily protected in the presence of trialkyl orthoformate and a catalytic amount of cerium(III) trifluoromethanesulfonate under mild conditions to give the corresponding acetals in good to excellent yields. Due to the mild reaction conditions, this method is compatible with acid-sensitive substrates. Copyright
- Ono, Fumiaki,Inatomi, Yoshiko,Tada, Yuusuke,Mori, Masaki,Sato, Tsuneo
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scheme or table
p. 96 - 97
(2009/11/30)
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- Pd supported on ZnII-CrIII mixed oxide as a catalyst for one-step synthesis of methyl isobutyl ketone
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Pd metal supported on ZnII-CrIII mixed oxide is an efficient bifunctional catalyst for the one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and H2 in the gas and liquid phases. The reaction involves acid-catalysed condensation of acetone to mesityl oxide, followed by its hydrogenation to MIBK. Diisobutyl ketone (DIBK) is a useful byproduct in this process. Zn-Cr oxides (Zn/Cr = 20:1-1:30) are prepared by coprecipitation of ZnII and CrIII hydroxides. The texture and acid properties (i.e., the nature, density, and strength of acid sites) of Zn-Cr oxides, as well as the Pd dispersion in the catalysts, are thoroughly characterised. For both the continuous gas-phase process and the batch liquid-phase process, the preferred catalyst formulation is 0.3 wt% Pd on the amorphous Zn-Cr (1:1) oxide (SBET = 132 m2 / g) having Lewis acid sites (1.2 mmol/g density) with an enthalpy of NH3 adsorption of - 155 kJ / mol. Both processes produce MIBK with a selectivity of 70-78% and 90% MIBK + DIBK total selectivity at 38-40% acetone conversion. Evidence is provided that hydrogenation of mesityl oxide to MIBK is the rate-limiting step in the gas-phase process.
- Al-Wadaani, Fahd,Kozhevnikova, Elena F.,Kozhevnikov, Ivan V.
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scheme or table
p. 199 - 205
(2009/02/07)
-
