1120-62-3Relevant articles and documents
AlPO4/TiO2 Catalysts. Part 2. - Structure, Texture and Catalytic Activity of Systems Precipitated with Ammonia or Ethene Oxide
Campelo, Juan M.,Garcia, Angel,Luna, Diego,Marinas, Jose M.,Moreno, Maria S.
, p. 2535 - 2554 (1989)
Two series of AlPO4/TiO2 (APTi) catalysts containing different weight compositions have been prepared by the precipitation of AlPO4 (Al/P = 1) on commercial TiO2 (> 99.9 percent Anatase, Aldrich) using ammonia (APTi-A series) or ethene oxide (APTi-E series) as the precipitation agents.Physicochemical characterization of these catalysts was carried our by nitrogen adsorption, TG, X. r. d.., i. r. spectroscopy and surface acid measurements.The surface area, pore volume, crystal structure and surface-acid character were found to be dependent on the precipitation agent, chemical composition and calcination temperature.Changes in surface-acid character were determined by application of a dynamic method that consists in determining both the AlPO4/TiO2's catalytic activity and selectivity in cyclohexene skeletal isomerization using the Bassett-Habgood kinetic model for first-order processes.X-ray diffraction studies show that the incorporated AlPO4 inhibits the polymorphic anatase-rutile transformation in the calcination process of the APTi-A system.Also, APTi-A systems are less affected by thermal treatment than APTi-E ones.It was found that both the apparent rate constant and the selectivity are dependent on the calcination temperature although the most important influence is that of catalyst composition i. e. the AlPO4/TiO2 weight ratio.Thus, a decrease in catalytic activity is observed when TiO2 content increases.Selectivity studies carried out by the OPE curves and the Wheeler criterion show that isomerization products, 1- and 3-methylcyclopentene, are competitive stable primary reaction products coming from cyclohexene across a parallel reaction network.
Alkylation of Allylic Derivatives. 10. Relative Rates of Reactions of Allylic Carboxylates with Lithium Dimethylcuprate
Goering, Harlan L.,Kantner, Steven S.,Seitz, Earl P.
, p. 5495 - 5499 (1985)
Relative rates of reaction of 19 allylic esters with LiCuMe2 in ether have been determined by a competitive reaction technique.The reactivity range for the series is >3*105.The relationship between structure and reactivity is compatible with a rate-limiting SN2' oxidative addition to give a ?-allyl copper(III) complex.
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Plate,A.F.,Stanko,V.J.
, (1960)
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Brown,Zweifel
, (1961)
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Photochemical and ESR spectral evidence for a stereoselective rearrangement of radical cations derived from azoalkanes and bicyclopentanes
Adam, Waldemar,Walter, Herbert,Chen, Guo-Fei,Williams, Ffrancon
, p. 3007 - 3014 (1992)
Studies of the photosensitized electron transfer (PET) reactions of anti/syn-5-methylbicyclo[2.1.0]pentane (1a,b) and syn/anti-7-methyl-2,3-diazabicyclo[2.2.1]hept-2-ene (2a,b) have revealed a remarkable stereochemical memory effect. Thus, 1a and 2a furnished only 1-methylcyclopentene (3a) as the rearrangement product, while their isomers 1b and 2b afforded predominantly 3-methylcyclopentene (3b). The pathway responsible for the stereoselective olefin formation can be assigned to a radical cation rearrangement. This was established on the basis of direct ESR evidence showing that the 1,3-diyl radical cations 1a,b?+ detected initially at 80-90 K following the radiolytic oxidation of 1a,b in CF3CCl3 rearranged stereoselectively into the olefin radical cations 3a,b?+ at 105 K. The ESR results further establish that, in the puckered conformations of 1a,b?+, the pseudo-axial substituent on the methylene bridge is in almost perfect coplanar alignment with the radical cation 2p orbital lobes, thus facilitating its stereoselective migration. Also, in agreement with PET results, matrix ESR studies demonstrated that, on radiolytic oxidation of the azoalkanes 2a,b, the olefin radical cations 3a,b?+ were formed with high selectivity, although no precursor radical cations were detected in this case.
Regioselective rearrangement of bridgehead-methyl-substituted radical cations derived from bicyclo[2.1.0]pentanes and 2,3-diazabicyclo[2.2.1]hept-2-enes through photoinduced electron transfer and radiolytic oxidation. Product distribution and matrix ESR studies
Adam,Sahin,Sendelbach,Walter,Chen,Williams
, p. 2576 - 2584 (1994)
Cyclopentane-1,3-diyl radical cations were generated from the 1-methyl- and 1,4-dimethyl substituted bicyclo-[2.1.0]pentanes 1b,c through photoinduced electron transfer (PET) and radiolytic oxidation. The unsymmetrical bridgehead-substituted bicyclopentane 1b rearranged spontaneously and exclusively to the 3-methylcyclopentene 3b under PET conditions. ESR studies showed similarly that 3b-+ was the only final oxidation product of 1b; the initial radical cation 1b-+ was not detected because it rearranges rapidly and stereoselectively by a 1,2-hydrogen shift to 3b-+, even at 80 K, and no trace of the more stable 1-methylcyclopentene radical cation 3a-+ was observed. This contra--thermodynamic regioselectivity is rationalized in terms of essential localization of positive charge at the tertiary center as the reaction proceeds in the 1,3-diyl radical cation 1b-+. The symmetrical dimethyl derivative 1c rearranged much more reluctantly than 1b despite its lower oxidation potential, and this is attributed to the greater persistence of radical cation 1c-+ through its reluctance to undergo a 1,2-H shift. This was confirmed by direct ESR observation, which also showed that the rearrangement of 1c-+ is much slower than that of the parent cyclopentane- 1,3-diyl radical cation 1-+. This difference is attributed to a larger effect of methyl stabilization on the reactant than on the product, leading to a decrease in exothermicity and an increase in the activation energy for the rearrangement of 1c-+ relative to that of 1-+. The 1-methyl and 1,4-dimethyl substituted 2,3-diazabicyclo [2.2.1]hept-2-enes 2b,c on PET reaction also yielded evidence for the intermediacy of 1,3-diyl radical cations; however, the product distributions suggest that denitrogenation can also be accompanied by concomitant 1,2-H shifts at the stage of the intermediate diazenyl radical cations, albeit with lower efficiency. ESR studies on the oxidation of 2c failed to detect the very stable 1c-+ species on the pathway to the 1,3-dimethylcyclopentene radical cation 3C-+, indicating that denitrogenation of 2C-+ results in a rapid rearrangement to 3c-+ even under matrix-isolation conditions at 77 K. Consequently, the oxidation of these azoalkanes generates highly reactive transients, presumably diazenyl radical cations, which readily denitrogenate and undergo 1,2-H shifts in either a consecutive or concerted manner to form olefin radical cations.
PROCESS FOR THE PREPARATION OF 1-METHYL-1-ALKOXYCYCLOPENTANES
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Page/Page column 5, (2012/05/04)
Process for the preparation of cyclopentane derivatives of the formula I in which R is a C1- to C10-alkyl group, which comprises reacting cyclohexanol or cyclohexene or mixtures of both compounds to give 1-methyl-1-cyclopentene (1st stage) and subsequently adding a C1- to C10-alkanol onto the double bond of the 1-methyl-1-cyclopentene (2nd stage).
The diagnostic substrate bicyclohexane reveals a radical mechanism for bacterial cytochrome P450 in whole cells
Austin, Rachel N.,Deng, Dayi,Jiang, Yongying,Luddy, Kate,Van Beilen, Jan B.,Ortiz De Montellano, Paul R.,Groves, John T.
, p. 8192 - 8194 (2008/02/08)
(Figure Presented) On home ground: The reaction mechanisms of bacterial alkane-oxidizing cytochrome P450s were determined in their native environment using a novel diagnostic substrate probe, bicyclohexane, in whole cells and cell-free extracts (see picture). Purified P450cam also oxidizes bicyclohexane. Clear evidence for a substrate-based radical with a lifetime of 75-250 ps was obtained.
