Temperature-dependent stereoselectivity and hydrogen deuterium kinetic isotope effect for .gamma.-hydrogen transfer to 2-hexyloxy radical. The transition state for the Barton reaction

1986 ◽  
Vol 108 (9) ◽  
pp. 2381-2387 ◽  
Author(s):  
Mark M. Green ◽  
Barbara A. Boyle ◽  
M. Vairamani ◽  
Triptikumar. Mukhopadhyay ◽  
William H. Saunders ◽  
...  
Keyword(s):  
Transition State ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Hydrogen Transfer ◽  
Temperature Dependent ◽  
Kinetic Isotope ◽  
Hydrogen Deuterium

Kinetic isotope effect for the thermally-induced migration of hydrogen in cyclopentadienes

1969 ◽  
Vol 47 (9) ◽  
pp. 1555-1559 ◽  
Author(s):  
Stewart McLean ◽  
C. J. Webster ◽  
R. J. D. Rutherford
Keyword(s):  
Transition State ◽  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Hydrogen Transfer ◽  
Arrhenius Parameters ◽  
Thermally Induced ◽  
Methyl Group ◽  
Hydrogen Migration ◽  
Kinetic Isotope ◽  
Non Linear

The Arrhenius parameters have been obtained for the rearrangement of 5-methylcyclopentadiene by a 1,2-hydrogen migration and for the corresponding rearrangement of 5-methylpentadeuteriocyclopentadiene. The results, taken in conjunction with those reported previously, allow the effect of the methyl group on the rate of hydrogen migration to be assessed. The kinetic isotope effect is of particular interest because the hydrogen transfer takes place through a transition state that is unequivocally non-linear.

Pressure effects on the rates of some hydrogen/deuterium transfer reactions between 2,2-Diphenyl-1-picrylhydrazyl and substituted phenols

1977 ◽  
Vol 30 (6) ◽  
pp. 1229 ◽  
Author(s):  
DA Palmer ◽  
H Kelm
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Hydrogen Transfer ◽  
Mean Value ◽  
Pressure Effects ◽  
Transfer Reactions ◽  
Substituted Phenols ◽  
Effect Of Pressure ◽  
Kinetic Isotope ◽  
Hydrogen Deuterium

The volumes of activation for hydrogen transfer reactions between 2,2- diphenyl-1-picrylhydrazyl (dpph) and a series of substituted phenols (2,4,6-tri-t-butylphenol, 2,6-di-t-butylphenol, 2,6-di-t-butyl-4- methylphenol, 2,4,6-trimethylphenol and 2,4,6-triphenylphenol) were measured in toluene at 25�C up to pressures of 2 kbar. The analogous deuterium transfer reactions were studied in the case of the first three phenols. The obtained volumes of activation, ΔV?expt proved to be independent of the nature of the phenol and the extent of deuteration. The overall mean value of ΔV?expt is -13�3 ml mol-1 and can be virtually entirely attributed to intrinsic molecular changes, ΔV?intr. From results of the effect of pressure on the first overtone of the O-H stretching frequency for a number of selected phenols in CS2, and from the lack of influence of pressure on the primary kinetic isotope effect, it is concluded that ΔV?ntr is essentially independent of moderate pressures.

Primary kinetic isotope effect in the gas phase photochlorination of ethyl chloride-1-d1

1984 ◽  
Vol 62 (5) ◽  
pp. 899-906 ◽  
Author(s):  
Jan Niedzielski ◽  
T. Yano ◽  
E. Tschuikow-Roux
Keyword(s):  
Activation Energy ◽  
Gas Phase ◽  
Isotope Effect ◽  
Ground State ◽  
Rate Constants ◽  
Kinetic Isotope Effect ◽  
Kinetic Isotope ◽  
Primary Reference ◽  
Hydrogen Deuterium ◽  
Increasing Temperature

The abstraction of hydrogen/deuterium from CH3CHDCl by ground state chlorine atoms produced photolytically from Cl2 has been investigated at temperatures betwen 280 and 368 K. The relative rates for the internal competition[Formula: see text]are found to conform to an Arrhenius rate law:[Formula: see text]These data, taken together with the external competition results for the C2H5Cl/CH3CHDCl system, in conjunction with the competitive results using CH4 as a primary reference, have yielded the rate constants (cm3 s−1):[Formula: see text]The relatively weak primary kinetic isotope effect, kH/kD, decreases with increasing temperature from 1,855 at 280 K to 1.66 at 365 K. The results are compared with those obtained based on the BEBO method. While both the trend and the magnitude of the kinetic isotope effect are satisfactorily predicted, the activation energy is not.

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