- 1,1-DICYCLOPENTADIENYL-3,3-DIMETHYLVANADA(IV)CYCLOBUTANE
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The reaction of 1,3-bis(bromomagnesio)-2,2-dimethylpropane (1b) with dichlorodicyclopentadienylvanadium(IV) (5) gave 1,1-dicyclopentadienyl-3,3-dimethylvanada(IV)cyclobutane (4) in 30percent yield, contaminated with dicyclopentadienylneopentylvanadium(III) (12).Attempts to purify 4 were only partially successful due to its limited stability (t1/2 = 4 h at 25 deg C in cyclopentane).Identification of 4 is therefore based on its having sufficient thermal stability for isolation, on its reaction with bromine to give 1,3-dibromo-2,2-dimethylpropane (2b), and especially on its ESR and 1H NMR spectra.The reaction of 4 with cyclohexanone (15) gave 17 and 18 as the main products; 17 is the aldol dimer of 15, while 18 may be derived from either 4 or 12.Because methylenecyclohexane (16) is not one of the reaction products, it is concluded that 4 does not have a pronounced tendency to fragment to give a metallacarbene (20).
- Seetz, J. W. F. L.,Heisteeg, B. J. J. Van De,Schat, G.,Akkerman, O. S.,Bickelhaupt, F.
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- New method for the synthesis of 2-aza-1,3-butadienes
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2-Aza-1,3-butadienes have been synthesized from carbonyl compounds and 1,1,1,3,3,3-hexamethyl-disilazane in the presence of cobalt-containing catalysts. The best yields (up to 95%) were achieved in the case of aldehydes branched in the α-position and 2-methylcyclohexanone. In the case of two α,β-unsaturated ketones, pyridine derivatives were found as the main products. Copyright Taylor & Francis Group, LLC.
- Sisak, Attila
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- Optimization of a cyclohexanone distillation stage in the presence of alkali
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Kinetics of two reactions: hydrolysis of esters and condensation of cyclohexanone in an alkaline environment, was studied in model mixtures. Derived kinetic equations were used to assess optimal parameters of proceeding cyclohexanone distillation in the presence of alkali.
- Glazko,Levanova,Martynenko,Sokolova
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- Baeyer-Villiger oxidation in supercritical CO2 with potassium peroxomonosulfate supported on acidic silica gel
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Supercritical carbon dioxide (scCO2) is an efficient reaction medium to perform the Baeyer-Villiger oxidation with hydrated silica-supported potassium peroxomonosulfate (h-SiO2·KHSO5) under flow-through conditions. Hydration modulates the reactivity of the active surface by softening the acidity of the KHSO4 present in the supported reagent. The reaction in scCO2 is much more efficient than in n-hexane under similar conditions, which is attributed to better transport and solvating properties of the supercritical medium with regard to n-hexane.
- Gonzalez-Nunez, Maria E.,Mello, Rossella,Olmos, Andrea,Asensio, Gregorio
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- Investigation of thermodynamic properties of trans-2-cyclohexylcyclohexanol
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A comprehensive study of thermodynamic properties of trans-2-cyclohexylcyclohexanol (t-2CCOL) was carried out in this work. The subject compound is a by-product from the synthesis of 2-phenylphenol. The standard molar enthalpy of combustion of t-2CCOL, found by the bomb calorimetry method, ΔcHom(cr,298.15 K) = - (7388.05 ± 1.37) kJ·mol-1, and the standard molar enthalpy of formation ΔfHom(cr,298.5 K) = - (478.25 ± 2.13) kJ·mol-1. The molar sublimation and vaporization enthalpies of t-2CCOL were measured with a heat-conduction differential microcalorimeter: ΔgcrHom(319.5 K) = (98.56 ± 0.52) kJ·mol-1; ΔgJHom(345.8 K) = (80.31 ± 0.34) kJ·mol-1. Vapour pressure of t-2CCOL was measured by the integral effusion Knudsen method in the temperature range 293 K to 325 K for crystal: ln(p/Pa) = (37.30 ± 0.22) - (11616 ± 69)·T-1, and in the temperature range 328 K to 364 K for liquid: ln(p/Pa) = (34.41 ± 0.44) - (10013 + 150)·T-1. The heat capacity of t-2CCOL was measured by the vacuum adiabatic calorimetry (T = 5 K to T = 338 K). The fusion temperature of t-2CCOL is 325.8 K, and the molar enthalpy of fusion is ΔfusHom = (14.515 ± 0.029) kJ·mol-1. Standard molar thermodynamic functions of t-2CCOL in the crystalline state at T = 298.15 K were obtained on the basis of these measurements: Cop,m = (248.68 ± 0.99); ΔT0Som = (263.85 ± 1.18); ΔT0Hom/T = (130.52 ± 0.51); Φom = (133.33 ± 1.29) J·K-1·mol-1.
- Maksimuk,Kabo,Kozyro,Simirsky,Krasulin,Sevruk
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- The introduction of a double bond on the steroid skeleton - The preparation of enol silyl ether derivatives from vicinal diols
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The ways of converting steroid vicinal diol into an unsaturated derivative were studied with the intention of preparing suitable precursors for the introduction of deuterium or tritium into the molecules of brassinosteroids. The model vicinal diol compound, 2α,3α-dihydroxy-5α-pregnane-6, 20-dione (3), was converted with high regioselectivity to the α-hydroxy ketone derivative, 2α-hydroxy-5α-pregnane-3,6,20-trione (8), in a 75% yield. The attempts to convert α-hydroxy ketone 8 to the dioxolene derivative, 2α,3α-(isopropylidenedioxy)-5α-pregn-2-ene-6,20- dione (6), failed. The conditions for the conversion of ketone to the corresponding enol trialkylsilyl ether were optimized using cyclohexanone as a model compound. The best and reproducible results were obtained by using tert-butyldimethylsilyl trifluoromethansulfonate (TBDMSiOTf) as the silylating reagent and triethylamine as the base. Under these conditions, the 3,6,20-trione (8) was converted to 2,3-bis(tert-butyldimethylsilyloxy)-5α-pregn-2-ene- 6,20-dione (14) with a 66% yield.
- Marek, Ales,Klepetarova, Blanka,Elbert, Tomas
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- Equilibrium Reactions in Supercritical Difluoromethane
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A dielectometry technique is used to follow the extent of two equilibrium reactions in supercritical difluoromethane (se HFC32), and the validity of the technique is demonstrated in the liquid state and compared to results obtained using gas chromatography-mass spectroscopy (GC-MS). The apparent equilibrium constant for the acid-catalyzed esterification of benzoic acid with 1-butanol decreased as the pressure increased, and this was proposed to be due to clustering at lower solvent density. In supercritical carbon dioxide (sc CO 2), the equilibrium constant was similar to that in se HFC32, despite the large difference in the dielectric constant of the fluids. The solute had a significant effect on the solution dielectric constant, such that the two solutions were similar. An acid-catalyzed aldol condensation reaction was also studied, and the apparent equilibrium constant was observed to change in a manner similar to that observed for the esterification reaction. The overall change in equilibrium constant was less than that observed for the esterification reaction and this was rationalized, in terms of the different dipole moments of the reagents in the two reactions.
- Abbott, Andrew P.,Corr, Stuart,Durling, Nicola E.,Hope, Eric G.
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- Alkylenation with Geminal Dialuminoalkane Reagents: The Synthesis of Olefins from Ketones
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Bis(dichloroalumino)methane (BDAM, 1) has been synthesized in high yield from aluminum powder and methylene chloride by a published procedure carefully modified for safety.By the screening away of aluminum metal fine particles and the gradual addition of methylene bromide promoter over the course of reaction, a safe procedure was attained.Although 1 itself was a poor methylenating agent for ketones, its dietherate complex was distinctly more reactive.By exchanging half the halogens of 1 with Me3Al, MeMgBr, or Et3Al, two very effective methylenating agents for ketones, namely CH2(AlClMe)2 (2) and CH2(AlClEt)2 (3), were obtained.As diether ates with Et2O or THF, 2 and 3 smoothly converted a broad variety of ketones (aliphatic, alicyclic, and aromatic) into their corresponding methylene derivatives, with little or no competitive alkylation or reduction.A titanium-modified reagent, Cl2AlCH2TiCl3 (4), was also effective toward ketones, but gave only low conversions of esters to vinyl ethers.Finally, as an example of a multicarbon, alkylenating agent, the reagents 5-7 ((R2Al)2CH(CH2)4CH3, 5, R = Et; 6, R = Cl; and 7, R = Cl or Et) were examined.Good to fair yields of alkylenation were obtained with aromatic ketones, but aliphatic ketones underwent alkylation, hydride reduction, and/or aldol condension.The great influence of alkyl groups and donor solvent on the reactivity of 1-3 is briefly discussed.
- Piotrowski, Andrzej M.,Malpass, Dennis B.,Boleslawski, Marek P.,Eisch, John J.
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- Conducting moisture sensitive reactions under mechanochemical conditions
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Dry organic solvents are used for various organic reactions that employ moisture sensitive reagents. The processes to dry these solvents are hazardous and costly. Setting up reactions in an open atmosphere while using moisture sensitive reagents has little to no effect on the rate or yield of the reaction under mechanochemical conditions. We believe this is partly due to the gaseous nature of the water vapor in the air compared to the dissolved water and oxygen in solution.
- Waddell, Daniel C.,Clark, Tammara D.,MacK, James
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- Thermal decomposition of quaternary oxazolidinium bases
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Thermal decomposition of the quaternary oxazolidinium bases is accompanied by the nucleophilic attack of the hydroxyl group at the C(2) carbon atom of the cycle to afford carbonyl compounds and aminoalcohols.
- Kukharev
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- Catalysis by Multimetallics. Catalyzed Homogeneous Oxidation of Alcohols and Ketones with Molecular Oxygen in the Presence of Hexarhodium Hexadecacarbonyl and Dirhenium Decacarbonyl
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The compounds Rh6(CO)16 and Re2(CO)10 are effective catalysts for the conversion of ketones and cyclic alcohols to carboxylic acids.Cyclohexanol is converted to adipic acid via cyclohexanone as intermediate.Temperature, solvent, and pressure effects are reported and discussed.Increased acid yield with Rh6(CO)16 under conditions of increased CO and decreased oxygen pressure are interpreted on the basis of a lower nuclearity rhodium carbonyl being the reactive intermediate.The catalytic effect of the metal carbonyl is a consequence of the accelerated decomposition of the preformed peroxide intermediates.The side product ε-caprolactone is formed in the oxidation of cyclohexanone, but the yield is decreased in the presence of Rh6(CO)16 because of the catalyzed decomposition of its precursor peracid.The metal carbonyls catalyze the decomposition of hydrogen peroxide, but unlike ferrous ion (Fenton's reagent) do not enhance its function as an organic oxidant.
- Roundhill, D. Max,Dickson, Mark K.,Dixit, Nagaraj S.,Sudha-Dixit, B. P.
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- ZUR HERSTELLUNG UND REAKTIVITAET VON BIS(TRIMETHYLSILYL)DILITHIOMETHAN
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At -90 deg C in THF or similar media bis(trimethylsilyl)dichloromethane 2 reacts with lithium-4,4'-di-tert-butylbiphenyl (LiDBB) or suspensions of freshly sublimed lithium to give the title compound 1 that can bind two equivalents of various electrophiles. 1 has a great propensity for proton abstraction and it is markedly less reactive towards ethyl iodide than (Me3Si)2EtCLi 6.
- Eikema Hommes, N. J. R. van,Bickelhaupt, F.,Klumpp, G. W.
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- Condensation of ketones in the presence of titanium alkoxides
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Titanium alkoxides promote successful condensation of aromatic and aliphatic ketones provided that the liberated alcohol is selectively removed from the reaction mixture.
- Yatluk,Sosnovskikh,Suvorov
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- Mg-Al layered double hydroxides: Synthesis, structure, and catalytic potential in condensation of cyclohexanone with acetonitrile
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Basic properties of synthetic Mg-Al layered double hydroxides were studied. It was shown that these properties strongly depend on the chemical composition and calcination temperature and are of key importance for determining the activity of catalysts based on these compounds. A relationship was found between the basic properties of these materials and the selectivity of conversion of the starting reagents to N-cyclohexylideneacetonitrile in condensation of cyclohexanone with acetonitrile.
- Belov,Markov,Sova,Stolyarova,Prikhod'Ko
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- Acid-catalyzed decomposition of cyclohexanespiro-2-oxazolidine
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Heating cyclohexanespiro-2-oxazolidine at 160-200°C in the presence of protic acids results in its decomposition to give N-(2-hydroxyethyl)cyclohexylamine, N-(2-hydroxyethyl)-4,5,6,7-tetrahydroindole, and 2-cyclohexylidenecyclohexanone. The possible pathways leading to these compounds are discussed.
- Kukharev
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- Aldol-type condensation reactions of cyclic ketones by the W(CO)6/CCl4/UV system
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The cyclic ketones can be converted to their aldol-type condensation products by the W(CO)6/CCl4/UV system. The reaction was monitored by recording the IR and GC-MS spectra of the reaction mixture. The results support a mechanism that includes an intermediate carbene complex of tungsten.
- Bozkurt
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- The influence of the preparation method on the physico-chemical properties and catalytic activities of ce-modified ldh structures used as catalysts in condensation reactions
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Mechanical activation and mechanochemical reactions are the subjects of mechanochem-istry, a special branch of chemistry studied intensively since the 19th century. Herein, we comparably describe two synthesis methods used to obtain the following layered double hydroxide doped with cerium, Mg3 Al0.75 Ce0.25 (OH)8 (CO3)0.5·2H2 O: the mechanochemical route and the co-precipitation method, respectively. The influence of the preparation method on the physico-chemical properties as determined by multiple techniques such as XRD, SEM, EDS, XPS, DRIFT, RAMAN, DR-UV-VIS, ba-sicity, acidity, real/bulk densities, and BET measurements was also analyzed. The obtained samples, abbreviated HTCe-PP (prepared by co-precipitation) and HTCe-MC (prepared by mechanochemical method), and their corresponding mixed oxides, Ce-PP (resulting from HTCe-PP) and Ce-MC (result-ing from HTCe-MC), were used as base catalysts in the self-condensation reaction of cyclohexanone and two Claisen–Schmidt condensations, which involve the reaction between an aromatic aldehyde and a ketone, at different molar ratios to synthesize compounds with significant biologic activity from the flavonoid family, namely chalcone (1,3-diphenyl-2-propen-1-one) and flavone (2-phenyl-4H-1benzoxiran-4-one). The mechanochemical route was shown to have indisputable advantages over the co-precipitation method for both the catalytic activity of the solids and the costs.
- Birjega, Ruxandra,Breze?tean, Ioana,Dumitru, Marius,Marcu, Ioan-Cezar,Matei, Andreea,Osiac, Mariana,Pavel, Octavian Dumitru,Stamate, Alexandra-Elisabeta,Z?voianu, Rodica
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- Beyond Takai's Olefination Reagent: Persistent Dehalogenation Emerges in a Chromium(III)-μ3-Methylidyne Complex
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Reaction of CHI3 with six equivalents of CrCl2 in THF at low temperatures affords [Cr3Cl3(μ2-Cl)3(μ3-CH)(thf)6] as the first isolable high-yield CrIII μ3-methylidyne complex. Substitution of the terminal chlorido ligands via salt metathesis with alkali-metal cyclopentadienides generates isostructural half-sandwich chromium(III)-μ3-methylidynes [CpR3Cr3(μ2-Cl)3(μ3-CH)] (CpR=C5H5, C5Me5, C5H4SiMe3). Side and decomposition products of the Cl/CpR exchange reactions were identified and structurally characterized for [Cr4(μ2-Cl)4(μ2-I)2(μ4-O)(thf)4] and [(η5-C5H4SiMe3)CrCl(μ2-Cl)2Li(thf)2]. The Cl/CpR exchange drastically changed the ambient-temperature effective magnetic moment μeff from 9.30/9.11 μB (solution/solid) to 3.63/4.32 μB (CpR=C5Me5). Reactions of [Cr3Cl3(μ2-Cl)3(μ3-CH)(thf)6] with aldehydes and ketones produce intricate mixtures of species through oxy/methylidyne exchange, which were partially identified as radical recombination products through GC/MS analysis and 1H NMR spectroscopy.
- Anwander, Reiner,Langmann, Jan,Maichle-M?ssmer, C?cilia,Scherer, Wolfgang,Trzmiel, Simon,Werner, Daniel
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supporting information
p. 20049 - 20054
(2021/08/06)
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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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- An unexpected reaction of camphor with sodium metal
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Reaction of camphor with sodium metal at elevated temperature in refluxing THF or toluene, furnishes an unexpected product. The product has been identified by spectral analysis and its structure confirmed by single crystal X-ray diffraction study. A preliminary mechanistic explanation has been suggested to explain this reaction.
- Khanvilkar, Aditya N.,Gupta, Riddhi,Bedekar, Ashutosh V.
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p. 1327 - 1331
(2015/11/10)
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- Synthesis and catalytic properties of ZSM-5 zeolite with hierarchical pores prepared in the presence of n-hexyltrimethylammonium bromide
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ZSM-5 samples with hierarchical pores (macropores, mesopores and micropores) were synthesized in the presence of n-hexyltrimethylammonium bromide (HTAB) and tetrapropylammonium hydroxide (TPAOH). The effect of synthesis conditions including the Si/Al ratio, crystallization temperature and time, and the amount of HTAB added to the synthesis system on the final products was examined. The catalytic properties of the hierarchical zeolite were investigated in reactions of Claisen-Schmidt condensation of benzaldehyde and acetophenone, self-condensation of cyclohexanone and methanol conversion. The hierarchical zeolite exhibits superior catalytic performance in Claisen-Schmidt condensation of benzaldehyde and acetophenone and self-condensation of cyclohexanone and has a remarkably high selectivity for dimethyl ether in the methanol conversion reaction at relatively low temperatures, which was attributed to the fast mass transport in the three-dimensional hierarchical pore network. A cooperative assembly mechanism accounting for the formation of the hierarchical zeolite was proposed based on experimental results.
- Bai, Peng,Wu, Pingping,Xing, Wei,Liu, Daolan,Zhao, Lianming,Wang, Youhe,Xu, Benjing,Yan, Zifeng,Zhao, Xiu Song
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p. 18586 - 18597
(2015/09/15)
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- Mass spectrometric studies of self-condensation products of cyclohexanone under alkaline conditions and synthesis of dodecahydrotriphenylene and triphenylene from easily available reactants
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LC-MS was used to study products of cyclohexanone self-condensation under alkaline conditions. Improved methods (as compared to those described in the literature) for the preparation of dodecahydrotriphenylene and highly pure sublimed triphenylene were suggested based on the easily available and cheap reactants. Possible reasons of the low yield of the target dodecahydrotriphenylene in the step of oligomerization of cyclohexanone were identified.
- Kovalev,Kopchuk,Zyryanov,Khasanov,Rusinov,Chupakhin
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p. 1539 - 1542
(2015/03/14)
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- The reductive amination of cyclohexanone with 1,6-diaminohexane over alumina B modified Cu-Cr-La/γ-Al2O3
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The reductive amination of cyclohexanone with 1,6-diaminohexane over alumina B modified Cu-Cr-La/γ-Al2O3 was investigated. The experimental results indicated that the doped alumina B remarkably increased the selectivity of N, N′-dicy
- Sun, Meng,Du, Xiaobao,Kong, Xiangjin,Lu, Liang,Li, Yang,Chen, Ligong
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experimental part
p. 58 - 62
(2012/06/16)
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- Comparative dehydrogenation of cyclohexanol to cyclohexanone with commercial copper catalysts: Catalytic activity and impurities formed
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Catalytic dehydrogenation of cyclohexanol to cyclohexanone has been carried out on phase gas in a continuous fixed bed reactor under atmospheric pressure. Copper chromite and copper zinc oxide catalysts have been checked. Effect of temperature (in the range 250-290 °C) and spatial time in reactor have been studied. The catalytic activity has been evaluated in terms of cyclohexanone yields and impurities from secondary reactions of dehydration and dehydrogenation of cyclohexanol have also been identified and quantified by GC/MS. Catalysts have been characterized by X-ray diffraction, temperature programmed desorption of ammonia and BET surface area measurement. High activity was confirmed by copper-based catalysts under the operating conditions, concerning the size and dispersion of the copper specie. It was also found that catalysts with alumina and chromium exhibit higher dehydration capacity, being cyclohexene the main impurity obtained. For a given cyclohexanone yield the impurities from dehydrogenation reactions showed similar trends for the three catalysts tested. Phenol was the main impurity obtained by dehydrogenation.
- Romero, Arturo,Santos, Aurora,Escrig, Daniel,Simón, Ernesto
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experimental part
p. 19 - 27
(2011/11/07)
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- METHOD FOR THE PRODUCTION OF 4,4'-[1-TRIFLUOROMETHYL)ALKYLIDENE]-BIS-(2,6-DIPHENYLPHENOLS)
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The present invention relates to a process for preparing 4,4′-[1-(trifluoromethyl)alkylidene]bis(2,6-diphenylphenols), in particular for preparing 4,4′-[1-(trifluoromethyl)ethylidene]bis(2,6-diphenylphenol), which comprises the self-condensation of cyclohexanone in the presence of a basic catalyst to form tricyclic condensation products, dehydrogenation of the resulting tricyclic condensation products in the presence of a supported transition metal catalyst in the condensed phase to form 2,6-diphenylphenol and reaction of the 2,6-diphenylphenol with a trifluoromethyl ketone. The invention further provides an improved process for preparing 2,6-diphenylphenol by aldol self-condensation of cyclohexanone.
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Page/Page column 9
(2010/12/29)
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- Selective hydrogenation of nitrocyclohexane to cyclohexanone oxime with H2 on decorated Pt nanoparticles
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A Pt catalyst has been designed to convert nitrocyclohexane into cyclohexanone oxime under mild hydrogenation conditions (4 bar of H2, 383 K, and solvent-free media). It has been found that the partial reduction of the nitro group to the oxime
- Serna, Pedro,Lopez-Haro,Calvino,Corma, Avelino
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scheme or table
p. 328 - 334
(2009/07/10)
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- Catalytic transfer hydrogenation of cycloalkanones on MgO. Vapour and liquid phase modes of reaction
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The reactivity of a series of cycloalkanones of the general formula (CH2)nCO, where n = 4, 5, 6, 7, 11 and 14 in the transfer hydrogenation reaction over magnesium oxide as the catalyst, either in vapour or liquid phase (VP or LP) has been studied. In the VP mode of reaction the activity of MgO treated with triethylamine, water, phenol or benzoic acid in the reduction of cyclopentanone by propan-2-ol has been determined. A strongly diminished or residual activity of MgO has been observed after the catalyst's treatment with phenol or benzoic acid, respectively. The occurrence of side reactions of cyclopentanone in the LP mode of reaction resulted in high conversions of the ketone (up to 91%), very low yields of cyclopentanol (I) (below 6%) and very high yields of 2-cyclopentyli- dene-cyclopentanone (II) (>80%).
- Glinski
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experimental part
p. 187 - 194
(2009/10/23)
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- Mechanistic studies on reaction of [ReH4(η2- H2)(Cyttp)]+ with ketones to give the hydrido-oxo complex [ReH2(O)(Cyttp)]+ (Cyttp = PhP(CH2CH 2CH2PCy2)2)
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Mechanistic studies were conducted on reaction of [ReH4(η 2-H2)(Cyttp)]OTf (1(OTf); Cyttp = PhP(CH 2CH2CH2PCy2)2, OTf = O3SCF3) with ketones, both neat and in solution. Treatment of 1(OTf) with excess acetone at 60-65°C affords [ReH2(O)(Cyttp) ]OTf (2(OTf)) in high yield, nearly 1 equiv. of H2, 2 equiv. of 2-propanol, 1 equiv. of each of 4-hydroxy-4-methyl-2-pentanone (B) and 4-methylpent-3-en-2-one (C), and smaller amounts of other organic products derived by condensation or related reactions of acetone. The presence of C, apparently arising by dehydration of B, points to the formation of 1 equiv. of H2O in the reaction system. Use of acetone-d6 in conjunction with 1(OTf) gives 2(OTf) containing no deuterium, as well as 1 equiv. of each of (CD3)2CHOH/OD and (CD3) 2CDOD/OH. Reactions of 1(OTf) with cyclohexanone, including cyclohexanone-2,2,6,6-d4, under comparable conditions, give analogous results. The ketones cyclopentanone, 2-butanone, and 3-pentanone also convert 1(OTf) to 2(OTf) upon heating, as does isobutyraldehyde, but only in the presence of the stabilizer BHT. In contrast, the more robust ketones 2,4-dimethyl-3-pentanone, 2,6-dimethylcyclohexanone, and 2-adamantanone, which do not undergo condensation, failed to effect this transformation. Other organooxygen compounds, i.e., methanol, cyclohexanol, 1,2-butene oxide, cyclohexene oxide, DMSO, and Me3NO, also are ineffective. A mechanism is proposed which begins with loss of H2 by 2 to give a 16-electron [ReH4(Cyttp)]+ which, depending on the experimental conditions, binds a solvent or ligand molecule. A [ReH 4(R2CO)(Cyttp)]+ intermediate generated in this manner reacts spontaneously by elimination of R2CHOH (containing methine hydrogen even when deuteriated ketone is used), which results from transfer of two hydride ligands to coordinated ketone. Continued reaction leads to the formation of 2 and another molecule of R2CHOH (containing methine deuterium when deuteriated ketone is employed), with the added hydrogens coming from H2O, which derives from solvent/reactant ketone.
- Rende, Dean E.,Wojcicki, Andrew
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p. 862 - 873
(2007/10/03)
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- Process for reducing the aldehyde concentration in a mixture comprising cyclohexanone and one or more aldehydes
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The invention relates to a process for reducing the aldehyde concentration in a mixture comprising cyclohexanone and one or more aldehydes, said process comprising distilling said mixture in a distillation column in the presence of an alkaline compound, wherein in the bottom of the distillation column substantially no water is present.
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- Base-catalyzed autocondensation of cyclohexanone
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Autocondensation of cyclohexanone in air at 119-137°C, catalyzed with a solid alkali, was studied.
- Trakhanov,Kruk,Maksimuk
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p. 1955 - 1957
(2007/10/03)
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- Synthesis of aryl-substituted piperidines by superacid activation of piperidones
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Diarylpiperidines (8-12) may be prepared in good to excellent yields (80-99%) by the reaction of piperidones (3d-h) with benzene and the Bronsted superacid, trifluoromethanesulfonic acid (CF3-SO3H, TfOH). Tropinone (6) and quinuclidone (7) also react in good yields with benzene in TfOH to give the condensation products (13 and 14). Ketal and acetal derivatives also give condensation products (8 and 24) upon reaction with C6H6 in TfOH. The conversion of 3g to 11 is sensitive to both acid quantity and acid strength; a mechanism is proposed for the conversion that invokes dicationic intermediates.
- Klumpp, Douglas A.,Garza, Manuel,Jones, Andre,Mendoza, Saray
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p. 6702 - 6705
(2007/10/03)
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- Organozinc reagents in synthesis: The facile generation of 2-(trialkylsilyl)prop-2-enylzinc from 2-bromo-1-trimethylsilylprop-2-ene
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A range of electrophiles react with 2-(trimethylsilyl)prop-2-enylzinc chloride, which is prepared by sequentially treating 2-bromo-1-trimethylsilylprop-2-ene with ButLi and then zinc chloride. The addition of transition metal catalysts can alter the reactivity of the organometallic compound from prop-2-enylation to prop-1-en-2-ylation.
- Eshelby, James J.,Parsons, Philip J.,Crowley, Patrick J.
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p. 191 - 199
(2007/10/03)
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- STEREOSELECTIVE SYNTHESIS OF THE TRICYCLIC CONDENSED DERIVATIVES OF THIAZOLIDINE
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The perhydro derivatives of thiazoloquinoline, thiazolocyclopentapyridine, thiazoloindole, and cyclopentapyrrolothiazole and also their 2-methyl derivatives were synthesized by the addition of thiirane and methylthiirane at the C=N bond in bicyclic imines of the 2,3,4,4a,5,6,7,8-octahydroquinoline type.An alternative method involves reaction of the thiiranes with amino ketones of the 2,2-ethylenedioxycyclohexylpropylamine type, protected at the carbomyl group, followed by acid deblocking and cyclization by treatment with alkali.The last method is the only method for the production of perhydrocyclopentapyrrolothiazoles, since 2,3,3a,4,5,6-hexahydrocyclopentapyrrole is not a stable imine.Some of the compounds were obtained in the form of single diastereomers, the configurations of which for the two subjects were determined by NMR.In other cases mixtures of the stereoisomers are formed with a srtong preponderance of one of them; arguments concerning their configurations are presented.It is shown that both methods of synthesis lead to an identical stereochemical result.
- Sokolov, V. V.,Potekhin, A. A.,Ovchinnikova, I. V.,Gindin, V. A.,Smirnov, S. N.
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p. 582 - 589
(2007/10/02)
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- REACTION OF 9-DIAZO-4-AZAFLUORENE WITH UNSATURATED COMPOUNDS AND CYCLIC KETONES
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Spiro were obtained by the reaction of 9-diazo-4-azafluorene with various alkenes in the form of a mixture of geometrical isomers differentiated according to the position of the substituents in the cyclopropane ring and also according to position relative to the pyridine ring.In the reaction of 9-diazo-4-azafluorene with cyclopentanone, di(4-azafluorene-9-yl) oxide is formed, while from its reaction with cyclohexanone, 2'-oxo-spiro is obtained.
- Prostakov, N. S.,Varlamov, A. V.,Hussein, A.,Fomichev, A. A.,Ryabova, N. A.,Stashenko, E. E.
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p. 424 - 430
(2007/10/02)
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- Reactivity of Dimethyl N-(Ethoxycarbonylmethyl)iminodithiocarbonate with Carbonyl Compounds in Basic Medium
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The reactivity of dimethyl N-(ethoxycarbonylmethyl)iminodithiocarbonate with aromatic aldehydes and reactive ketones has been studied.Ethyl 3-aryl-2-(methylcarbonylamino)acrylates (1) are obtained with aromatic aldehydes by ring-opening isomerization of the intermediate 5-aryl-4-ethoxycarbonyl-2-methylthio-4,5-dihydro-1,3-oxazoles (2).With ketones it has been shown that the cycloalkanones give rise to the corresponding alkylidene derivatives by a reaction path identical with that of aromatic aldehydes, whereas hexafluoropropanone and 1,1,1-trifluoropropanone display duality in acting as both acylating reagents and carbonyl compounds.
- Alvarez-Ibarra, Carlos,Lopez-Ranz, Maria M.,Lopez-Sanchez, Maria I.,Orellana, Guillermo,Ortiz, Paloma,Quiroga, Maria L.
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p. 1577 - 1584
(2007/10/02)
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- Interannular Diastereoselectivity in the Hydroboration of Functionalized 1-Cyclohexylcyclohexenes
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The reactions of thexylborane with 2-(1-cyclohexen-1-yl)cyclohexanone, cis-2,6-di(1-cyclohexen-1-yl)cyclohexanone, and related alcohols and ketals were investigated.All reactions are selective for products with erythro linkages between cyclohexyl rings, diastereoselectivities ranging from 66 to 97percent.Greatest erythro selectivities were observed for equatorial homoallylic alcohols and ethylene ketals.The configurations of all products were unambiguously assigned by correlation with -2,2'-diones and an erythro, erythro triketone (25), the configuration of which was determined by X-ray crystallography.The diastereoselectivities of these hydroborations and related examples from the literature can be qualitatively rationalized by the Houk transition structure model.
- Bell, Thomas W.,Vargas, J. Ramon,Crispino, Gerard A.
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p. 1978 - 1987
(2007/10/02)
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- AUTOCONDENSATION OF CYCLOHEXANONE
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Depending on the selected temperature and reaction conditions, the autocondensation of cyclohexanone can either be limited by the aldol condensation stage or can lead to the formation of a mixture of 2-(1-hydroxycyclohexyl)cyclohexanol, 2-cyclohexenylcyclohexanone, and 2-cyclohexylidenecyclohexanone.The aldol condensation takes place at a high rate and is reversible.The nature of the solvent does not affect the 2-cyclohexanone = 2-(1-hydroxycyclohexyl)cyclohexanone equilibrium.The addition of water to the reaction system inhibits the crotonization of 2-(1-hydroxycyclohexyl)cyclohexanone but does not affect the aldol condensation stage.
- Efimova, G. A.,Shutova, I. V.,Shapiro, Yu. E.,Efimov, V. A.,Turov, B. S.,Makarov, V. M.
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p. 1081 - 1084
(2007/10/02)
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- THERMAL SELF-CONDENSATION OF CYCLOHEXANONE
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The thermal self-condensation of cyclohexanone, resulting in a mixture of isomeric 2-cyclohexylidenecyclohexanone (I) and 2-cyclohex-1'-enylcyclohexanone (II), with predominance of the latter, was studied.The conversion of cyclohexanone into these two product was followed in time by gas chromatography.The transient radical intermediates were trapped with 2-methyl-2-nitrosopropane and detected by EPR in the reaction medium.
- Kaim, Andrzej,Kaminski, Jaroslaw,Kolodziejski, Waclaw
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p. 141 - 146
(2007/10/02)
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- COMPOSITION AND REACTIVITY OF POD OIL.
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The objective of this work is to study the composition of POD oil and the kinetics of its interaction with maleic anhydride. The most interesting information on the composition of POD oil was obtained with the aid of gel permeation chromatography. All the samples of POD oil contain 50-60% of oligomers of molecular weight 330-380. The contents of other fractions are lower; they include 6. 8-30. 7% of a light fraction of mol. wt. 90-126. This fraction probably contains CL and CN. The contents of fractions of higher molecular weight are greatest in ShPOD and GPOD, and lower in SPOD.
- Chernaya,Mikhal'kov,Salistyi
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p. 1109 - 1112
(2007/10/02)
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- LIQUID-PHASE ALDOL CONDENSATION OF CYCLOHEXANONE ON ALUMINIUM AND IRON OXIDES
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The kinetics of the aldol condensation of cyclohexanone in decalin were investigated at 210 deg C on catalysts prepared by drying and calcining the aluminium and iron hydroxides at 110-850 deg C.The effect of catalyst poisoning by benzoic acid and pyridine on the course of the condensation reaction and aldol retroaldolisation was also examined.The kinetics of the cyclohexanone condensation can be described by means of Langmuir-Hinshelwood equations which are in agreement with a mechanism involving adsorption of cyclohexanone on a basic site to form a transient complex, reaction of this complex with a cyclohexanone molecule affording the aldol, the rate determinig interaction of the aldol with free basic and acid sites yielding 2-(1-cyclohexen-1-yl)cyclohexanone and water and desorption of these products from the catalyst surface.The proposed kinetic model is supported by the results of catalyst poisoning.The activity of aluminium and iron oxides in the condensation of cyclohexanone is a complex function of their basicity and acidity depending strongly on the calcination temperature.
- Vit, Zdenek,Nondek, Lubomir,Malek, Jaroslav
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p. 2235 - 2245
(2007/10/02)
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- Organometallic Compounds. XI. Chlorotrimethylsilane / Sodium Bromide - A Simple System for the in situ Generation of Bromotrimethylsilane. Reaction with Ketones, Sulfoxides, and Various Oxygen Containing Substrates
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Bromotrimethylsilane is generated in situ by the addition of chlorotrimethylsilane (2) to a solution or a suspension of sodium bromide (or LiBr, KBr, MgBr2).The reaction of the in situ generated bromotrimethylsilane with ketones, sulfoxides, γ-butyrolactone, triethyl orthoformate, and trialkyl phosphites is described.
- Schmidt, Arthur H.,Russ, Manuel
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p. 1099 - 1110
(2007/10/02)
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