Showing papers on "Cyclohexene published in 1993"
TL;DR: In this article, the epoxidation of lower olefins, catalysed by titanium silicalite (TS-1) under mild conditions, is reported. But the reaction may be performed at near room temperature, in dilute alcoholic or aqueous solutions of hydrogen peroxide.
671 citations
TL;DR: In this article, the gas phase reactions of O 3 with a series of alkenes have been investigated at 296±2 K and atmospheric pressure of air in the presence of cyclohexane at concentrations sufficient to scavenge any OH radicals formed.
Abstract: The gas-phase reactions of O 3 with a series of alkenes have been investigated at 296±2 K and atmospheric pressure of air in the presence of cyclohexane at concentrations sufficient to scavenge any OH radicals formed. The expected products of the OH radical-initiated reaction of cyclohexane, cyclohexanone and cyclohexanol, were observed in all cases. From a knowledge of the chemistry of cyclohexane in these reaction systems and the cyclohexanone and cyclohexanol formation yields obtained, the following formation yields of OH radicals in these O 3 -alkene reactions were derived: propene, 0.33; 1-butene, 0.41; 2-methylpropene, 0.84; cis-2-butene, 0.41; trans-2-butene, 0.64; 2-methyl-1-butene, 0.83; 2-methyl-2-butene, 0.89; 2,3-dimethyl-2-butene, 1.00; cyclohexene, 0.68; 1,3-butadiene, 0.08; all with estimated overall uncertainties of a factor of ∼1.5
266 citations
TL;DR: In this article, the vapour phase hydrogenation of phenol over platinum and palladium supported on alumina and zeolite LTL was studied in a vertical fixed-bed high-pressure reactor.
Abstract: The vapour-phase hydrogenation of phenol over platinum and palladium supported on alumina and zeolite LTL was studied in a vertical fixed-bed high-pressure reactor. The major products of the hydrogenation reaction were cyclohexanone and cyclohexanol with cyclohexane, cyclohexene and benzene as the minor products. The selectivity for the major products was upto 99%, the conversion being influenced by temperature, feed rate and the partial pressure of hydrogen. Platinum catalysts were found to be better for the production of cyclohexanol while palladium catalysts favoured cyclohexanone production. The platinum catalysts also showed twice as much overall conversion as the palladium catalysts.
90 citations
69 citations
01 Jul 1993
TL;DR: In this paper, data of vapor sorption measurements of the solvents cyclohexane, benzene and toluene in polyurethane (PU) membranes are presented.
Abstract: Data of vapor sorption measurements of the solvents cyclohexane, benzene and toluene in polyurethane (PU) membranes are presented. Vapour sorption isotherms have been obtained from equilibrium data. Kinetic sorption data have been used for determining diffusion coefficients of the solvents in the membrane material. Further measurements of the individual solubilities of liquid cyclohexane+benzene and cyclohexane+toluene mixture components in PU-membrane material have been carried out using the so-called swelling density method and a gaschromatographic analytical method. Vapor sorption isotherms as well as solubility data of the liquid mixtures can be described with the UNIQUAC-model in good agreement with experiments. All results obtained for solubilities and diffusion coefficients are used for predictive calculations of fluxes and separation diagrams in the pervaporation process of cyclohexane+benzene and cyclohexane+toluene mixtures through PU-membranes. The basis of these model calculations is the solution-diffusion model. Predicted results of pervaporation agree well with experimental data taken from literature provided diffusion coupling of the components permeating the membrane is taken into account.
55 citations
TL;DR: Vanadium complexes formed from VO (acac) 2 as the starting material for the catalysts have been characterized in situ with 51 V and 1 H NMR and EPR in the course of three types of catalytic reactions as mentioned in this paper.
53 citations
TL;DR: In this paper, deuterium atoms formed on a hot tungsten filament are impinged onto a Cu(111) surface precovered with cyclohexane, and dehydrogenated products are evolved when the surface is heated in subsequent temperature-programmed reaction (TPR) experiment.
Abstract: Cyclohexane desorbs molecularly intact from Cu(111) and does not react with deuterium atoms that are preadsorbed on the surface By contrast, when deuterium atoms formed on a hot tungsten filament are impinged onto a Cu(111) surface precovered with cyclohexane, dehydrogenated products (cyclohexene, cyclohexadiene, and benzene) are evolved when the surface is heated in a subsequent temperature-programmed reaction (TPR) experiment These D-atom-induced dehydrogenation products provide strong evidence for an Eley-Rideal mechanism where D atoms abstract hydrogen from cyclohexane prior to thermal accommodation with the surface The kinetics of cyclohexene evolution indicate that both single and sequential H-atom abstractions occur by this mechanism
51 citations
50 citations
TL;DR: In this article, two new phenylbutenoid dimers, (±)-trans-3-(2,4,5-trimethoxyphenyl)-4-[(E)-3,4-dimethoxystyryl]-cyclohexene and cis-1,2-bis[(E) 3,4]-cyclobutane, have been isolated from the fresh rhizomes of Zingiber cassumunar along with the two known phenyl butenoid compounds.
43 citations
TL;DR: In this article, a synergy in the hydrogenation of cyclohexene and hydrodesulfurization of thiophene is observed when the so-called "NiMoS" phase, prepared by the HSP method, is mixed with Co9S8.
43 citations
TL;DR: In this article, four chelating resins derived from crosslinked poly(chloromethylstyrene) (PCMS), four derived from poly(glycidylmethacrylate) (PGMA), and one cross linked poly(4-vinylpyridine) resin have been used to immobilise Mo complexes.
TL;DR: In this paper, the epoxidation of cyclohexene, 1-decene, and styrene by molecular oxygen in the presence of aldehydes such as isobutyraldehyde and pivalaldehyde was efficiently catalyzed at 303 K by mono-cobalt-substituted Keggin-type heteropolytungstate.
Abstract: The epoxidation of cyclohexene, 1-decene, and styrene by molecular oxygen in the presence of aldehydes such as isobutyraldehyde and pivalaldehyde was efficiently catalyzed at 303 K by mono-cobalt-substituted Keggin-type heteropolytungstate.
TL;DR: In this article, the second order rate coefficients for the epoxidation of trans-ethyl cinnamate (3) and cyclohexene (4) by dimethyldioxirane have been obtained in a number of binary solvents.
Abstract: Second order rate coefficients for the epoxidation of trans-ethyl cinnamate (3) and cyclohexene (4) by dimethyldioxirane have been obtained in a number of binary solvents. These data were treated by the Kamlet–Taft multi-parameter solvent effect equation. These analyses indicate that solvents with hydrogen bond donor capacity (HBD) increase the rate of these reactions while solvents with hydrogen bond acceptor (HBA) capacity decrease the rate. Variable temperature rate determinations for the cyclohexene epoxidation permitted the calculation of Ea, log A, and transition state parameters for several solvent systems. These data also support the favourable effect of HBD solvents on the rate of epoxidation by dimethyldioxirane.
TL;DR: In this paper, an aqueous suspension of zinc sulphide photocatalyses the dehydrodimerization of 3,4-dihydro-2 H -pyran, 4-methyl-5,6-dioxioxioxypyran and cyclohexene under concomitant hydrogen evolution.
Abstract: An aqueous suspension of zinc sulphide photocatalyses the dehydrodimerization of 3,4-dihydro-2 H -pyran, 4-methyl-5,6-dihydro-2 H -pyran and cyclohexene under concomitant hydrogen evolution Maximum turn-over numbers are in the range of 3000 monolayers While three regioisomers are obtained from the two first substrates, cyclohexene affords the 2,2′ isomer exclusively The most reactive zinc sulphide samples have specific surface areas of about 100 m 2 g −1 and an excess of sulphur at the surface These samples do not suffer photocorrosion when irradiated in a suspension of pure water However, this occurs with samples of lower surface area and excess zinc at the surface
TL;DR: Using 17O, 95Mo and 1H NMR spectroscopy, the composition and reactivity of molybdenum (VI) complexes formed in the course of the catalytic epoxidation of cyclohexene and allylic alcohol with hydrogen peroxide in aprotic solvents were studied.
TL;DR: Ru/Cu/SiO 2 catalysts were obtained using sol-gel and impregnation methods, and activated with hydrogen before and after calcination as mentioned in this paper, and four types of the catalysts obtained were characterized by TEM, XRD, XPS, and adsorption of hydrogen, benzene, cyclohexene and water.
Abstract: Ru/Cu/SiO 2 catalysts were prepared using sol-gel and impregnation methods, and activated with hydrogen before and after calcination. The four types of the catalysts obtained were characterized by TEM, XRD, XPS, and adsorption of hydrogen, benzene, cyclohexene and water. From the results, it was found that the catalysts which have fine metal particles and low adsorptive abilities for hydrogen and cyclohexene, for example, lwt%Ru/O. lwt%Cu/SiO 2 prepared by sol-gel method and activated before Calcination, are suitable for the production of cyclohexene. It was also concluded that the roles of water in the partial hydrogenation of benzene with the Ru/Cu/SiO 2 catalyst are to expel and isolate cyclohexene from the catalyst surface.
TL;DR: In this article, the influence of γ-Al 2 O 3 loading and the calcination temperature of APALA catalysts on their surface acidity (number and strength distribution) was studied by means of the chemisorption (gas-chromatographically measured) of pyridine and 2,6-dimethylpyridine (DMPY) at temperatures in the 473-673 K range.
Abstract: The influence of γ-Al 2 O 3 loading (5–25 wt.-%) and the calcination temperature of AlPO 4 -Al 2 O 3 (APALA) catalysts on their surface acidity (number and strength distribution) was studied by means of the chemisorption (gas-chromatographically measured) of pyridine (PY) and 2,6-dimethylpyridine (DMPY) at temperatures in the 473–673 K range. In addition, cyclohexene skeletal isomerization (CSI) and cumene conversion (CC), were selected as dynamic methods for surface acid characterization. The AlPO 4 -Al 2 O 3 catalysts were found to show greater number and strength of acid sites than each individual component. The addition of Al 2 O 3 even in a small amount (5 wt.-%), could significantly improve the activity and catalytic activity of AlPO 4 catalysts. Moreover, the catalytic activity of the APAl-A catalyst for both reactions varied with Al 2 O 3 loading and, thus, it increased gradually as the Al 2 O 3 content of the catalyst increased up to 15 wt.-%, after which it decreased. Good correlations between catalytic activity and the increase in acidic properties of the AlPO 4 by Al 2 O 3 loading (as determined by base chemisorption) have been obtained for both reactions. Qualitative DRIFT spectroscopy of probe molecules [pyridine (PY), 2,6-dimethylpyridine (DMPY) and hexamethyldisilazane (HMDS)] showed that P-OH and Al-OH groups disappeared on adsorption and that both Lewis and Brensted acid sites existed on the surface of APA1-A catalysts. Furthermore, the involvement of strong acid sites in CSI and CC reactions has been investigated by selectively poisoning the acid sites with PY, DMPY and HMDS. The catalytic activity and selectivity of the APAl-A catalyst were strongly affected by this poisoning. Thus, Bronsted acidity was considered to be the common active site on APA1-A catalysts.
TL;DR: In this article, the hydrogenation of several liquid alkenes was studied over Pd/Ru alloy membranes in either metal or glass membrane reactors, and the results showed that cyclohexene, cyclo-octadiene, and octadecene as liquids were common in contrast to the facile conversion of acetylenic alcohols.
Abstract: The hydrogenation of several liquid alkenes was studied over Pd/Ru alloy membranes in either metal or glass membrane reactors. For cyclohexene, cyclo-octadiene, and octadecene as liquids, conversions of ca. 2–5% were common in contrast to the facile conversion of acetylenic alcohols.
TL;DR: Cobalt chloride in diglyme is a useful catalyst for the allylic oxidation of cyclohexene, affording 2-cyclohexen-1-ol as the major product and 2-cyclecycloen-en-one as the byproduct.
TL;DR: In this article, both enantiomers of the reduced methoxyamino alcohol (MAM) were efficiently prepared by utllizing S-serine, and the corresponding oxazolines showed favorable properties toward additions to naphthalenes and cyclohexene.
Abstract: By utllizing S-serine, both enantiomers of the reduced methoxyamino alcohol (12) were efficiently prepared. The corresponding oxazolines, prepared from these auxiliaries, showed favorable properties toward additions to naphthalenes 22 and cyclohexene, 27
TL;DR: In this article, the NO3 radical initiated oxidation of cyclopentene, cyclohexene and 1-methyl-cyclohexenes has been studied using long path FTIR.
Abstract: The NO3 radical initiated oxidation of cyclopentene, cyclohexene and 1-methyl-cyclohexene has been studied. The products formed in an N2O5-NO2-N2-O2-cycloalkene-static reactor system, at 0.1 MPa and 296 K, were investigated using long path FTIR. The principal products were aldehydes formed via a ring opening process. The reactions also resulted in significant yields of three types of ring retaining nitrooxy-substituted compounds. The average yields of alkyl nitrates from, e.g., reactions with cycloalkene were 25.1% 2-oxo-cyclohexyl nitrate, 22.8% 2-hydroxy-cyclohexyl nitrate and 4.0% 1,2-cyclohexyl dinitrate. The mechanisms involved resembles those proposed for acyclic alkenes. In absence of NO, α-oxo and α-hydroxy-cycloalkyl nitrates are formed via self reactions of α-nitrooxy substituted cycloalkyl peroxy radicals. Estimated branching ratios for the reactants leading to ring retaining products in the presence and in the absence of NO are given and the possible relevance of these reactions for cycloalkenes under tropospheric conditions is discussed.
TL;DR: In this article, the kinetics of bromine addition to various deuterated isotopomers of cyclohexene, namely the parent (3a), 3,3,6,6-tetradeuteriocyclohexenes (3b), and cycloenene-d 10 (3c), have been determined in HOAc (T=25 o C) as a function of added [Br - ], and the products were determined.
Abstract: The kinetics of bromine addition to various deuterated isotopomers of cyclohexene, namely the parent (3a), 3,3,6,6-tetradeuteriocyclohexene (3b), and cyclohexene-d 10 (3c), have been determined in HOAc (T=25 o C) as a function of added [Br - ], and the products were determined. The observed kinetic isotope effect for bromination of 3a/3b is k H /k D ≃1.0 with no added salt and indicates that deuteration of the allylic positions does not influence the kinetics
TL;DR: In this paper, two sources for hydrogen are recognized: hydrogen supplied by the gas phase and hydrogen which is available inside the metal hydride particles, assuming a fast dissociative adsorption of hydrogen.
TL;DR: In this paper, the terminal phosphinidene complex PhPW(CO) 5 with cyclohexene, 1,4-cyclohexadienes, and 1,3-cycloehexadiene was investigated.
Abstract: The reaction of the terminal phosphinidene complex PhPW(CO) 5 with cyclohexene, 1,4-cyclohexadienes, and 1,3-cyclohexadiene win investigated. In all cases a mixture of syn- and anti-phosphiranes is obtained. The syn-vinylphosphirane resulting from reaction with 1,3-cyclohexadiene rearranges at 110 o C to a phospholene, wherein the anti-isomer decomposes. The formation of syn- and anti-phosphiranes is discussed in terms of kinetic versus thermodynamic control
TL;DR: The trilithium salt 7, prepared from 5 or 6, with diethyl carbonate and triphenyl phosphite yields 4-sila and 8-phospha-4-silathiophenetriptycenes, 2 and 3, respectively as mentioned in this paper.
TL;DR: Using 95Mo, 1H, 17O NMR and EPR, this paper characterized molybdenum (VI) complexes formed in the course of catalytic epoxidation of cyclohexene with tert-butyl and cumene hydroperoxides.
TL;DR: Tetronothiodin is a potent and selective cholecystokinin type B (CCK-B) receptor antagonist produced by Streptomyces sp.
Abstract: Tetronothiodin (1) is a potent and selective cholecystokinin type B (CCK-B) receptor antagonist produced by Streptomyces sp. NR0489. Its structure was elucidated to be a macrocyclic compound comprising cyclohexene, alpha-acyltetronic acid and tetrahydrothiophene moieties based on various 2D NMR experiments on 1 and its dihydro derivative. The stereochemistries for the cyclohexene and tetrahydrothiophene rings were elucidated based on the analysis of NOEs obtained by NOESY experiments and NOE difference spectroscopy. The relative configuration of the cyclohexene moiety in 1 was revealed to be the same as that of the corresponding part in kijanimicin and chlorothricin, which can be structurally related to 1 in terms of their containing a cyclohexene ring with a spirotetronic acid in the molecule.
TL;DR: A series of cycloalkenes were adsorbed onto activated H-mordenite, and their transformations investigated with EPR as mentioned in this paper, which monitors the catalytic transformations which occur, by detecting the radical cations formed from unsaturated intermediates with low ionisation potentials.
Abstract: A series of cycloalkenes were adsorbed onto activated H-mordenite, and their transformations investigated with EPR. This technique monitors the catalytic transformations which occur, by detecting the radical cations formed from unsaturated intermediates with low ionisation potentials. Cyclopentene and cyclohexene were found to take part in dimerisation and ring enlargement reactions. Medium sized rings, cyclooctene and cyclodecene underwent transannular ring closure, as did cyclododecene, to form bicyclo[n.n.0]alkenes (n= 3, 4, 5).
TL;DR: In this article, the influence of precipitation medium and thermal treatment of CrPO4(Cr: P = 1) catalysts on their surface acidity (number and strength distribution) was studied by means of the gas-phase chemisorption of pyridine and 2,6-dimethylpyridine (DMPY) at 573 and 673 K.
Abstract: The influence of the precipitation medium and thermal treatment of CrPO4(Cr: P = 1) catalysts on their surface acidity (number and strength distribution) was studied by means of the gas-phase chemisorption of pyridine (PY) and 2,6-dimethylpyridine (DMPY) at 573 and 673 K. In addition, Cyclohexene skeletal Isomerization (CSI) and cumene conversion (CC), were selected as dynamic methods for surface acid characterization. Catalysts obtained in propylene oxide–aqueous ammonia exhibited a higher number and strength of acid sites and, hence, greater activity in CSI and CC processes, than catalysts obtained in propylene oxide or aqueous ammonia exclusively. Moreover, cumene dehydrogenation (to α-methylstyrene) always predominated over cumene dealkylation (to propylene and benzene) and accounted for 100% selectivity of CrP-A and CrP-P catalysts. Furthermore, a correlation between surface acidity and catalytic activity was found.
TL;DR: In this paper, the reaction with simple vinyl compounds and dimethyl acetylenedicarboxylate was shown to give cyclic 1 : 2-, 2 : 1- and 2 : 2-addition products, namely substituted cyclohexadiene or benzene, cyclopentene and cyclooctadiene derivatives, which can be separated by column chromatography.