- Reactivity of 1,3-dimethylimidazolium-2-carboxylate with dimethylcarbonate at high temperature: Unexpected 2-ethyl-functionalisation of the imidazolium moiety and employment of the NHC-CO2/dimethylcarbonate system in a base promoted reaction
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The reaction of 1,3-dimethylimidazolium-2-carboxylate and dimethylcarbonate (DMC) at high temperature yielded the new compounds 2-ethyl-1,3- dimethylimidazolium methyl carbonate salt and 2-ethyl-1,3-dimethylimidazolium-4- carboxylate zwitterion which were obtained as a mixture in approximately 4:1 molar ratio. The compounds were also isolated in pure form through alternative synthetic procedures and characterized by ESI-HRMS, 1H, 13C NMR and FTIR spectroscopy. The 1,3-dimethylimidazolium-2- carboxylate/dimethylcarbonate system was employed in the synthesis of 1,7-heptanedioic acid dimethyl ester from cyclohexanone and DMC. The target compound was obtained in 49% yield and 66% selectivity.
- Annese, Cosimo,D'Accolti, Lucia,Fusco, Caterina,Tommasi, Immacolata
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Read Online
- Aldol Condensation Catalyzed by Highly Electron Deficient Iron Porphyrin
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The perchlorate complex of 2,4,6,8-tetratrifluoromethyl-1,3,5,7-tetraethylporphyrin*Fe(III) shows the extraordinarily positive reduction potential, 0.81 V vs.Ag/AgCl (reversible).The complex catalyzes the aldol condensation of cyclohexanone. - Key Words: porphyrin, Aldol condensation, catalysis, redox potential
- Kuroda, Yasuhisa,Suzuki, Yasuhiko,Ogoshi, Hisanobu
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Read Online
- Catalytic synthesis of 2-(1-cyclohexenyl)cyclohexanone by mixed heteropoly acids catalyst (PW12 + PMo12/SBA-15)
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Mixed heteropoly acids (phosphotungstic acid and phosphomolybdic acid) supported on SBA-15 (PW12 + PMo12/SBA-15) by impregnation method was used as catalysts of self-condensation reaction of cyclohexanone to synthesize the 2-(1-cyclohexenyl)cyclohexanone. The experimental results indicated that the mixed heteropoly acids supported on SBA-15 had effective catalytic performance, which catalytic synthesis of 2-(1-cyclohexenyl)cyclohexanone. The effects of various parameters on the conversion ratio such as the amount of catalyst, loading amount, reaction time and reaction temperature were investigated. The optimum reaction conditions were as follows: The loading of the PW12 + PMo12/SBA-15 was 29%, the percentage of catalyst in reactants was 3%, the reaction time was 2.5 h and the reaction temperature was 150°C. The conversion rate could reach 86.5%.
- Wang, Ying-Ying,Wu, Bo,Liu, Chun-Li,Li, Fu-Xiang,Lv, Zhi-Ping,Xue, Jian-Wei
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Read Online
- 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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- Highly selective self-condensation of cyclic ketones using MOF-encapsulating phosphotungstic acid for renewable high-density fuel
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Transferring biomass-derived cyclic ketones such as cyclopentanone and cyclohexanone to a mono-condensed product through aldol self-condensation has great potential for the synthesis of a renewable high-density fuel. However, the selectivity is low for numerous catalysts due to the rapid formation of di-condensed by products. Herein, MIL-101-encapsulating phosphotungstic acid is synthesized to catalyze the self-condensation with selectivity of more than 95%. PTA clusters are uniformly dispersed in MOF cages and decrease the empty space (pore size), which provides both acidic sites and shape-selective capability. The optimal PTA amount decreases corresponding to the increase of reactant size. The shape-selectivity is also realized by changing the pore size of MOF such as from MIL-101 to MIL-100. Moreover, the catalyst is resistant to PTA leaching and performs stably after 5 runs. After hydrodeoxygenation of the mono-condensed product, high-density biofuels with densities of 0.867 g ml-1 and 0.887 g ml-1 were obtained from cyclopentanone and cyclohexanone, respectively. This study not only provides a promising route for the production of high-density biofuel but also suggests the advantage of MOF-based catalysts for shape-selective catalysis involving large molecular size.
- Deng, Qiang,Nie, Genkuo,Pan, Lun,Zou, Ji-Jun,Zhang, Xiangwen,Wang, Li
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supporting information
p. 4473 - 4481
(2015/08/11)
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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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- Iodine-catalyzed cycloalkenylation of dihydroquinolines and arylamines through a reaction with cyclic ketones under neat conditions
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An iodine-catalyzed direct cycloalkenylation of dihydroquinolines and arylamines has been developed. This method consists of a Friedel-Crafts reaction between dihydroquinolines (or arylamines) and cyclic ketones in which the double bond is selectively generated throughout the course of the reaction resulting in a direct cycloalkenylation, under neat conditions.
- Fotie, Jean,Ayer, Suraj K.,Poudel, Binit S.,Reid, Carolyn S.
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supporting information
p. 7069 - 7073
(2013/12/04)
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- Comparison of the catalytic activity of [(η5-C 5H5)Ru(2,2′-bipyridine)(L)]OTf versus [(η5-C5H5)Ru(6,6′-diamino-2,2′- bipyridine)(L)]OTf (L = labile ligand) in the hydrogenation of cyclohexanone. Evidence for the presence of a metal-ligand bifunctional mechanism under acidic conditions
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The two title complexes as well as the dimeric complex [Ru(II) (η5-C5H5)(6,6′-diamino-2,2′- bipyridine)]2(OTf)2 have been synthesized and characterized by NMR and single-crystal X-ray crystallography. The direct structural comparison of the 2,2′-bipyridine and 6,6′-diamino-2, 2′-bipyridine complexes suggests that the electronic and steric environments of the ruthenium centers in both complexes are essentially equivalent, providing for a unique opportunity to probe the influence of the noncoordinated amine substituent on the relative reactivity and catalytic activity of the complexes. Opposite to what would be anticipated on the basis of steric effects, the bulkier amine-substituted ligand results in a catalyst showing substantially higher activity in the hydrogenation of cyclohexanone in acidic medium, which is attributed to the operation of a metal-ligand bifunctional hydrogenation mechanism mediated by the amine substituents in their protonated form acting as proton shuttles.
- Dimondo, Domenico,Thibault, Michelle E.,Britten, James,Schlaf, Marcel
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p. 6541 - 6554
(2013/12/04)
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- PROCESS FOR PRODUCING 2-(CYCLOHEX-1'-ENYL)CYCLOHEXANONE
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The present invention discloses a process for producing 2-(cyclohex-1′-enyl)cyclohexanone by an auto-condensation of cyclohexanone at a certain temperature in the presence of a certain solid acidic catalyst.
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Page/Page column 2
(2012/03/26)
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- Unexpected 5,6,7,8,9,10-hexahydro-6,6-pentamethylenephenanthridines and 2,3,4,5-tetrahydro-4,4-tetramethylene-1 H -cyclopenta[ c ]quinolines from skraup-doebner-von miller quinoline synthesis and their implications for the mechanism of that reaction
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The real mechanism of the Skraup-Doebner-Von Miller quinoline synthesis remains controversial and not well understood despite several mechanistic studies reported on the matter. A series of unexpected and unusual 5,6,7,8,9,10-hexahydro-6,6-pentamethylenephenanthridines and 2,3,4,5-tetrahydro-4,4-tetramethylene-1H-cyclopenta[c]quinolines have been obtained through the Skraup-Doebner-Von Miller quinoline synthesis. On the basis of these unexpected results and in agreement with some of the previously reported quinoline syntheses, an alternative mechanistic pathway is proposed for this variant of the reaction. It involves the formation of a Schiff base through a reaction between the ketone and the aniline derivative in the first step, followed by a cycloalkenylation at the ortho-position to the amine functional group of the aniline derivative, and an annulation in the final step to close the quinoline ring, leading to a dihydroquinoline derivative. To the best of our knowledge, this is the first report of such a mechanistic pathway being proposed for any variant of the Skraup-Doebner-Von Miller quinoline synthesis.
- Fotie, Jean,Kemami Wangun, Hilaire V.,Fronczek, Frank R.,Massawe, Nancy,Bhattarai, Bijay T.,Rhodus, Jessica L.,Singleton, Thomas A.,Bohle, D. Scott
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experimental part
p. 2784 - 2790
(2012/05/20)
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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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- 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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experimental part
p. 1767 - 1771
(2012/02/05)
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- A selective solvent-free self-condensation of carbonyl compounds utilizing microwave irradiation
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An environmentally benign microwave-assisted solvent-free self-condensation of carbonyl compounds was developed using catalytic amounts of triethylamine and lithium perchlorate. Changing the amount of lithium perchlorate helps in controlling the ratio of the single-condensation and double-condensation products. The effect of other additives and microwave activation was also investigated. The optimized conditions were then applied to various cyclic/acyclic ketones and aldehydes, with selectivity observed in many cases.
- Sharma, Lalit Kumar,Kim, Kyung Bo,Elliott, Gregory I.
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supporting information; experimental part
p. 1546 - 1549
(2011/07/31)
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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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- Reductive amination of cyclohexanone in the presence of cyclohexanol over zeolites Hβ and HY
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Reductive amination of a mixture of cyclohexanone/cyclohexanol in varying proportions has been carried out in the gas phase over zeolites Hβ and HY. The products identified were cyclohexylamine, N-cyclohexylcyclohexanimine, 2-cyclohexen-1-ylcyclohexanone and 2-cyclohexylcyclohexanone. The product distribution during the experiments indicates that cyclohexanol does not undergo reductive amination over acid catalysts; it only forms a condensation product with cyclohexanone. The reaction rates were obtained from experimental data and fit to a kinetic model derived for this reaction. The fits show that this reaction follows a Langmuir-Hinshelwood pathway by the adsorption of both cyclohexanone and the NH3 on the surface of the zeolite.
- Kirumakki, Sharath R.,Papadaki, Maria,Chary, Komandur V.R.,Nagaraju
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experimental part
p. 15 - 21
(2010/10/04)
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- Practical synthesis of gem-difluorides from cyclohexanone: Synthesis of gem-bistrifluoroacetates and their reactions with fluoride nucleophiles
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Formation of ketone acylals bearing trihaloacetoxy groups and their nucleophilic geminal disubstitution by fluoride ions were investigated. Cyclohexanone reacted with trifluoroacetic anhydride without catalyst to give gem-bistrifluoroacetates via a concerted bimolecular reaction. Treatment with hydrogen fluoride under mild conditions efficiently yielded the corresponding gem-difluorides. In this reaction process, trifluoroacetic acid was recovered and converted to trifluoroacetic anhydride using P2O5. Since gem-difluorides were derived from ketones, HF and P2O5, this constitutes a practical synthesis of gem-difluorides.
- Tojo, Masahiro,Fukuoka, Shinsuke,Tsukube, Hiroshi
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experimental part
p. 29 - 35
(2010/03/30)
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- Hetero-diels-alder reactions of cyclic ketone derived enamide. A new and efficient concept for the asymmetric robinson annulation
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Chiral enamides, easily prepared in one step from a cyclic ketone and an oxazolidinone, are successfully employed in high-yielding, endo, and facially selective Hetero-Diels-Alder reactions involving activated oxadienes and Siever's reagent as catalyst. F
- Gallier, Florian,Hussain, Hidayat,Martel, Arnaud,Kirschning, Andreas,Dujardin, Gilles
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supporting information; experimental part
p. 3060 - 3063
(2009/12/06)
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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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p. 1705 - 1708
(2007/10/03)
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- Synthesis of unsymmetric trisannelated benzenes using a SOCl 2/EtOH reagent
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A simple and efficient method for the synthesis of unsymmetric trisannelated benzenes is presented. The dimers of cycloketones react with molecules of other cycloketones to form corresponding unsymmetric trisannelated benzenes in the presence of thionyl chloride in anhydrous ethanol.
- Hu, Zhiguo,Dong, Zhibing,Liu, Jun,Liu, Wenjie,Zhu, Xinling
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p. 603 - 604
(2007/10/03)
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- A new lewis acid system palladium/TMSCl for Catalytic aldol condensation of aldehydes with ketones
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Palladium on charcoal effectively catalyzed the aldol condensation reactions of different ketones with aldehydes in the presence of trimethylsilyl chloride (TMSCl). The following reactions were investigated: (1) aromatic aldehydes with cycloalkanones, (2) aromatic aldehydes with aromatic ketones, (3) cycloalkanones with aliphatic aldehydes, and (4) the self-condensation reactions of aliphatic aldehydes and cycloalkanones.
- Zhu, Yulin,Pan, Yuanjiang
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p. 668 - 669
(2007/10/03)
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- Reduction of carbonyl compounds with polyethylsiloxane in the presence of titanium compounds
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Reduction of carbonyl compounds with polyethylsiloxane in the presence of titanium alkoxides gives the corresponding alcohols in high yields.
- Kozhukhova,Yatluk,Suvorov,Koryakova
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p. 759 - 762
(2007/10/03)
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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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- Indium trichloride catalyzes aldol-condensations of aldehydes and ketones
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InCl3·4H2O catalyzes the cross-aldol condensation of different ketones with various aldehydes to give α,β-unsaturated carbonyl compounds in good to excellent yields.
- Deng, Guisheng,Ren, Tiegan
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p. 2995 - 3001
(2007/10/03)
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- Trisannelated benzene synthesis by copper(II) chloride
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Different ketones such as cyclohexanone, cyclopentanone, acetophenone, 2-acetonaphthalene, 4-methylcyclohexanone in the presence of anhydrous CuCl 2 (catalytic amounts) at reflux condition for 2-4 hours, without using a solvent led to dimers 2-(1-cyclohexane-1-yl)-cyclohexanone 6, 2-cyclopentylidene cyclopentanone 10, trimer dodecahydrotriphenylene (DTP) 4, trindan (tricyclopentabenzene) 9,1,3,5-triphenylbenzene (TBP) 12a, 1,3,5-triss-naphthylbenzene 12b and dodecahydro-2,6,10- trimethyltriphenylenes 17 and 18.
- Mahmoodi, Nosrat O.,Hajati, Nezam
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- Ring-opening reactions of cyclic acetals and 1,3-oxazolidines with halosilane equivalents
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Reactions of acetal and 1,3-oxazolidine rings were examined using two kinds of iodosilane equivalent reagents, a 1:2 mixture of Me3SiNEt2 and MeI (reagent 1a) and a 1:1 mixture of Et3SiH and MeI containing a catalytic amount of PdCl2 (reagent 1b). In the reactions of alkanone ethylene acetals with reagent 1a, a C-O bond in the acetal ring readily cleaved to give 2-(trimethylsiloxy)ethyl enol ethers. Similarly, the C-O bond of 1,3-oxazolidine rings cleaved to give ring-opened imine or enamine derivatives. The reactions of aromatic ketone ethylene acetals and cyclohexanone trimethylene acetal led to deprotection of the acetal unit to liberate free ketones. With reagent 1b, cycloalkanone ethylene acetal afforded a dimeric product with 2-iodoethyl alkenoate moieties, while aromatic ketone ethylene or trimethylene acetals produced deprotected ketones.
- Iwata, Arihiro,Tang, Heqing,Kunai, Atsutaka,Ohshita, Joji,Yamamoto, Yasushi,Matui, Chinami
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p. 5170 - 5175
(2007/10/03)
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- Amidino derivatives useful as nitric oxide synthase inhibitors
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The current invention discloses useful pharmaceutical compositions containing amidino derivative useful as nitric oxide synthase inhibitors.
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- Amidino dervatives useful as nitric oxide synthase inhibitors
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The current invention discloses useful pharmaceutical compositions containing azepine derivatives useful as nitric oxide synthase inhibitors.
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- RuCl3 catalyses aldol condensations of aldehydes and ketones
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Anhydrous RuCl3 catalyses the efficient cross aldol condensations of different ketones with various aromatic aldehydes in sealed tube under solvent free conditions without the occurrence of any self condensations. Regioselective self condensation reaction of some ketones and aldehydes are also described. The catalytic effect of Ru(III) is shown by performing similar reactions under thermal conditions without catalyst.
- Iranpoor, Nasser,Kazemi, Foad
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p. 9475 - 9480
(2007/10/03)
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- Thiomethylation of ketones by sodium sulphide and formaldehyde
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The thiomethylation of propanol, butanol, cyclohexanone and acetophenone with a mixture of formaldehyde and sodium sulphide proceeds at 20°C and normal pressure for 1-7 hr. It has been established that the reactivity of ketones increases in the order butanone-cyclohexanone-propanone-acetophenone. The conversion of sodium sulphide depends on its initial concentration, the nature of the ketone, and the presence in the reaction medium of sodium hydroxide and ethyl alcohol. It has been shown that the reaction proceeds with the preferential formation of keto- and diketosulphides.
- Ulendeyeva,Bayeva,Lyapina,Shmakov,Galkin
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p. 177 - 186
(2007/10/03)
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- Aldol Reaction and Robinson-Type Annelation Catalyzed by Lanthanoid Triisopropoxides
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Lanthanoid triisopropoxides are active catalysts for aldol reactions.Aldehydes give the corresponding β-hydroxyaldehydes at low temperatures in good yields, whereas ketones are less reactive, but form condensation products at high temperatures.Exceptionally, γ- or δ-diketones easily undergo condensation to give five- and six-membered unsaturated ketones in high yields.The lanthanoid propoxides, catalyzing the Michael addition of ketones to α,β-unsaturated ketones, which give δ-diketones, are also good catalysts for the Robinson-type annelation.In these reactions, the catalytic activity of the lanthanum propoxide is higher than those of the heavy lanthanoid propoxides, and is almost comparable to that of sodium isopropoxide.Since aluminum triisopropoxide shows poor activity, the lanthanoid propoxides are considerably basic for trivalent metal alkoxides.
- Okano, Tamon,Satou, Yoshikazu,Tamura, Motoshi,Kiji, Jitsuo
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p. 1879 - 1886
(2007/10/03)
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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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p. 687 - 699
(2007/10/03)
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- Electrochemical and Catalytic Initiation of Triethyl Phosphite Addition to Cyclohexanone
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Electrochemical oxidation of triethyl phosphite in the presence of cyclohexanone results in a mixture of three products: diethyl(1-ethoxycyclohexyl)phosphonate, diethyl phosphonate, and 2-(1-cyclohexenyl)cylcyclohexanone. These products are formed through the stage on the anode synthesis of quasiphosphonium salts, which initiate addition of triethyl phosphite to cyclohexanone and condensation of cyclohexanone. The fact that quasiphosphonium salts catalyze addition of the phosphite to the ketone was proved by independent experiment.
- Romakhin,Zagumennov,Nikitin
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p. 256 - 259
(2007/10/03)
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- THERMODYNAMIC CHARACTERISTICS OF BY-PRODUCTS FROM CAPROLACTAM SYNTHESIS
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The bomb calorimetry method was used to determine enthalpies of combustion and to calculate enthalpies of formation for 2-cyclohexylcyclohexanone, 2-cyclohexenylcyclohexanone, and 2-cyclohexylidenecyclohexanone.The saturation vapor pressure of compounds (I)-(II) was measured using the Knudsen integral effusion and tensimetry methods.A calculation was made of coefficients A and B in the equation ln (P/Pa)=A-BT-1.Differential microcalorimetry was employed to find enthalpies of vaporization.Using the triple bridge method heat capacity was measured in the ranges 150-500 deg and 270-470 K; the thermodynamic fusion properties of the compounds were also established.
- Marachik, L. I.,Kozyro, A. A.,Simirskii, V. V.,Kabo, G. Ya.,Yursha, I. A.,et al.
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p. 710 - 715
(2007/10/02)
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- ON THE DIRECT METALATION OF ISOPRENE
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Isoprene has been metalated in tetrahydrofuran with an excess of sterically hindered potassium dialkylamides, prepared by combining equimolar amounts of the corresponding lithium amide and potassium tert-butoxide.Subsequent reaction with oxirane, alkyl bromides, and pivaldehyde gave the expected coupling products in reasonable yields.Coupling with (CH3)2CHCH2CH=O and (CH3)2C=CHCH=O afforded the bark beetle pheromones (+/-)-ipsenol and (+/-)-ipsdienol in low yields.
- Klusener, P. A. A.,Tip, L.,Brandsma, L.
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p. 2041 - 2064
(2007/10/02)
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- Reactions of alkali metal anions. XV. Reaction of ketones with alkali metal anions
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The potassium anions were found to react with ketones to39 yield both alcoholates and enolates. On the basis of the ESR and K NMR measurements the mechanism of this reaction is proposed. According to the proposed mechanism in the first step a ketyl radical is formed which after disproportionation yields an enolate and an alcoholate but only in the case of ketones having hydrogen atom in α-position in respect to carbonyl group.
- Jedlinski,Misioiek,Giowkowski,Janeczek,Wolinska
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p. 3547 - 3558
(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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- 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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Irradiation of bicyclic aromatic and aliphatic dienamides in neutral solvent yields a variety of oxazines possessing a spiroheterocyclic framework. The hexatrienic character of these systems is not a prerequisite to their photoannelation but the presence of aromatic units in the parent models strongly modifies their photoreactivity.
- Bochu, Christophe,Couture, Axel,Lablache-Combier, Alain
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p. 1959 - 1970
(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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- REDUCTIVE METHYLENATION OF KETONES OF POTASSIUM HYDROXIDE-DIMETHYL SULFOXIDE SUSPENSION
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Ketones react with a potassium hydroxide-DMSO suspension at 100-110 deg C to form allyl alcohols containing an additional methylene group (with yields of up to 37percent).The key stage in the reductive methylenation of the ketones is the addition of the dimsyl ion to the carbonyl group. 2-Methylthio ketones, which are the products from methylthiylation of the enolate ions of the intermediately formed methanesulfenate esters, are formed in parallel (with yields of up to 10percent).
- Trofimov, B. A.,Mikhaleva, A. I.,Petrova, O. V.,Sigalov, M. B.
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p. 1889 - 1894
(2007/10/02)
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- Catalytic reactions of metalloporphyrins. II. Activation and catalytic aldol condensation of ketone with rhodium(III)-porphyrin perchlorate under neutral and mild conditions
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Acetone and methyl ethyl ketone undergo facile and direct metalation at the methyl groups by a cationic (octaethylporphyrinato) rhodium(III) complex with a non-coordinating perchlorate counteranion, (OEP)RhIII(ClO4), under mild conditions.Acetylacetone and ethyl acetoacetate are similarly metalated at the internal methylene groups.The metalation of acetone is first-order with respect to both rhodium complex and ketone, and involves the (OEP)RhIII(ClO4)-assisted, rate-determining enolization of the ketone.The resulting 2-oxopropyl-rhodium derivative undergoes facile cleavage of the C-Rh bond with electrophiles such as H(1+) and Br2.When cyclohexanone is used as substrate, on the other hand, (OEP)RhIII(ClO4) catalyzes the aldol condensation of the ketone effectively, where the intermediate cyclohexanone enolate reacts with the ketone or other carbonyl compound present and regenerates the RhIII complex.An essential aspect of the present reaction is the remarkable ability of (OEP)RhIII(ClO4) to promote enolization of simple ketones by activation with charge-separated III>+ (a Lewis acid) under mild and neutral conditions.The second-order rate constant of (OEP)RhIII(ClO4)-assisted enolization of acetone at 30 deg C (k2 = 2.6 * E-4 M-1 sec-1) is E7 times as large as that of its spontaneous enolization in water, where water is both acid and base.
- Aoyama, Y.,Tanaka, Y.,Yoshida, T.,Toi, H.,Ogoshi, H.
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p. 251 - 266
(2007/10/02)
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- Cross-Condensation Reactions of Cycloalkanones with Aldehydes and Primary Alcohols under the Influence of Zirconocene Complexes.
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Under the influence of zirconocene complex,Cp2ZrH2 (1) or Cp2Zr(O-i-Pr)2 (9),cycloalkanones 2 condensed directly with aliphatic aldehydes 3 or primary alcohols 7 to form 2-alkylidenecycloalkanones 4 or 2-alkyl-2-cycloalken-1-ones 8,respectively,in fair to substantial yields.The selectivity of the cross-condensations was slighty improved by using 1 in combination with a metal salt such as NiCl2.Dihydrojasmone (13) was synthesized in 35percent yield by one-step reaction from the commercially available 3-methylpentanone (2e) with pentanol (7b) in the presence of 1 and NiCl2.
- Nakano Tatsuya,Irifune Shinji,Umano Shigetoshi,Inada Akihiro,Ishii Yasutaka,Ogawa Masaya
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p. 2239 - 2244
(2007/10/02)
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- Hydroalkylation of Phenol to Cyclohexylphenyl in the Presence of Pd-Al2O3 and NaCl-AlCl3 under Hydrogen Pressure
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The hydroalkylation of phenol (1) in the presence of palladium catalyst and fused salt (NaCl-AlCl3) under hydrogen pressure was carried out.By using 1percent Pd-Al2O3 (1g) and the fused salt (1:1 mol ratio, 6g), 4-cyclohexyphenol (6) was obtained selectively from 1 (30g) in a yield of 31.9 percent at 120 deg C for 4.5 h.Cyclohexylphenols were formed by way of 2-cyclohexen-1-ol and 1.Keywords-hydroalkylation; palladium catalyst; fused salt; phenol; 2-cyclohexylphenol; 4-cyclohexylphenol; 2-cyclohexylcyclohexanone
- Kamiyama, Tsutomu,Enomoto, Saburo,Inoue, Masami
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p. 450 - 454
(2007/10/02)
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- Preparation and Some Reactions of Diarylgermylenedialkali Metals
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The reactions of diarylgermanes with alkali metals in HMPA/THF or THF were found to give the corresponding diarylgermylenedialkali metals in high yields.Diphenylgermylenedipotassium reacted with aryl halides or carbonyl compounds to give reduction products predominantly.With alkyl halides, diphenylgermylenedipotassium gave mainly substitution products.
- Mochida, Kunio,Matsushige, Naoki,Hamashima, Mari
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p. 1443 - 1447
(2007/10/02)
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- Reaction of Lithium with Alkylidene Halides and Carbonyl Compounds
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While benzylidene bromide reacts with aromatic aldehydes and lithium to give stilbenes, the reaction with aliphatic carbonyl compounds as well as that of alkylidene halides with carbonyl compounds and lithium are complicated by several competing side reactions.
- Pasha, M. A.,Ravindranath, B.
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p. 781 - 782
(2007/10/02)
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