A STUDY OF SOME REACTIONS OF THE CYCLOPENTYL RADICAL

1965 ◽  
Vol 43 (3) ◽  
pp. 570-581 ◽  
Author(s):  
Alvin S. Gordon
Keyword(s):  
Hydrogen Atom ◽  
Kinetic Parameters ◽  
Rate Constant ◽  
Energy Of Activation ◽  
Radical Reactions ◽  
Specific Rate ◽  
Exponential Factor ◽  
Allyl Radical ◽  
Specific Rate Constant ◽  
Activated Complex

The specific rate constant for opening the cyclopentyl radical has been determined to be 1014.5 exp –37 700/RT s−1. The energy of activation indicates that any eclipsed pairs of H atoms in the cyclic radical are not de-eclipsed in the activated complex. No evidence for the resulting five-membered linear radical can be found, only evidence for its breakdown products, allyl radical and ethylene.The disproportionation/combination ratio for methyl and cyclopentyl radicals is about 0.3. The energy of activation for methyl abstracting a hydrogen atom from cyclopentane has been confirmed as about 9.5 kcal/mole.Cyclopentyl radical also loses a hydrogen atom to form cyclopentene. The kinetic parameters are difficult to obtain because of radical–radical reactions which form cyclopentene. An analysis of the results indicates an energy of activation at least equal to that for opening the cyclopentyl ring.Evidence is presented to support the view that the cyclopentyl radical loses a molecule of hydrogen to form the resonance-stablized cyclopentenyl radical with an energy of activation close to that for opening the ring, and a pre-exponential factor about 1/10 of that for the opening of the ring.

Effect of variable specific rate constant in non uniform catalysts

1977 ◽  
Vol 32 (2) ◽  
pp. 155-159 ◽  
Author(s):  
J. Cervelló ◽  
J.F.J. Melendo ◽  
E. Hermana
Keyword(s):  
Rate Constant ◽  
Specific Rate ◽  
Specific Rate Constant

Temperature jump kinetics of the binding of imidazole to ferriprotoporphyrin IX

1969 ◽  
Vol 47 (17) ◽  
pp. 3225-3232 ◽  
Author(s):  
Brian B. Hasinoff ◽  
H. Brian Dunford ◽  
Dale G. Horne
Keyword(s):  
Dissociation Constant ◽  
Rate Constant ◽  
Temperature Jump ◽  
Spectrophotometric Titration ◽  
Specific Rate ◽  
Specific Rate Constant ◽  
Solvent Systems ◽  
Ph Scale ◽  
Kinetics Of ◽  
Imidazolium Ion

The kinetics of binding of imidazole to ferriprotoporphyrin IX (hemin) in aqueous ethanol has been studied at 25° using the temperature jump technique. The reaction was studied quantitatively as a function of acid concentration using the pH scale developed by Bates et al. for mixed solvent systems. The results can be explained by a mechanism in which the imidazolium ion binds to hemin with a specific rate constant of (4 ± 2) × 106 M−1 s−1 and imidazole binds with a rate constant of (3 ± 0.3) × 104 M−1 s−1. The dissociation constant for the imidazolium ion was determined by acid–base titration to be 1.8 × 10−7 M, and a dissociation constant for the hemin of 2.3 × 10−7 M was determined by spectrophotometric titration in a solvent containing 44.5 weight % of ethanol. The latter dissociation involves the proton on a solvent ligand.

scholarly journals Facet-dependent performance of BiOBr for photocatalytic reduction of Cr(vi)

RSC Advances ◽  
2016 ◽  
Vol 6 (3) ◽  
pp. 2028-2031 ◽  
Author(s):  
Zao Fan ◽  
Yubao Zhao ◽  
Wei Zhai ◽  
Liang Qiu ◽  
Hui Li ◽  
...  
Keyword(s):  
Electric Field ◽  
Rate Constant ◽  
Photocatalytic Reduction ◽  
Specific Rate ◽  
Internal Electric Field ◽  
Specific Rate Constant

BiOBr dominated with {110} facets giving a specific rate constant 3 times as high as BiOBr with {001} facets, and its much stronger internal electric field was believed to be the main reason.

SPECIFIC RATE CONSTANT FOR URETHAN CLEAVAGE

1963 ◽  
Vol 67 (4) ◽  
pp. 930-931 ◽  
Author(s):  
A. V. Tobolsky ◽  
E. Peterson
Keyword(s):  
Rate Constant ◽  
Specific Rate ◽  
Specific Rate Constant

A second species of polynuclear hydroxyaluminum cation, its formation and some of its properties

1976 ◽  
Vol 54 (12) ◽  
pp. 1910-1915 ◽  
Author(s):  
Robert C. Turner
Keyword(s):  
Lower Energy ◽  
Energy Of Activation ◽  
Specific Rate ◽  
Dialysis Membrane ◽  
Order Process ◽  
First Order ◽  
Specific Rate Constant ◽  
Solid Phases ◽  
Experimental Values ◽  
Exchangeable Form

When a solution of Al(ClO4)3 or AlCl3 with total Al concentration between 5 × 10−4 and 6 × 10−2 M is partially neutralized very slowly with a base, it is possible to produce a solution of polynuclear hydroxyaluminum cations with no solid phases present. When such a solution is aged, the polynuclear hydroxyaluminum cations, AlP1, disappear very slowly at 25 °C and a second type of polynuclear hydroxyaluminum cations, AlP2, is formed. The second type, AlP2, has some properties that are the same as those of AlP1, e.g. they both have an OH/Al mole ratio equal to or very nearly equal to 2.5, diffuse readily across a dialysis membrane, and are removed from solution by the clay mineral bentonite in an exchangeable form. Some of their properties, however, are entirely different, e.g. AlP1 reacts with 8-hydroxyquinoline about 250 times faster with a much lower energy of activation than does AlP2, is much less resistant to attack by HCl, and is precipitated at a pH about 0.5 pH units lower than AlP2. The transformation of AlP1 to AlP2 is a first order process with an energy of activation of 20.8 kcal per mol. The specific rate constant seems to be affected somewhat by the extraneous anion present and the degree of neutralization; experimental values varied from 0.57 × 10−3 to 3.5 × 10−3 day−1 at 25 °C.

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