22311-39-3Relevant articles and documents
Effect of solvation on the reaction rate constants of the diphenylaminyl radical with phenols and hydroquinones
Antonov,Denisov,Nadtochenko,Varlamov
, p. 91 - 96 (2008/02/13)
The kinetics of the reactions of the diphenylaminyl radical with unhindered phenols and hydroquinones in acetonitrile at 294 K was studied by laser flash photolysis. The rate constants k range from 104 to 106 L mol-1 s-1 and depend on the nature of substituents in phenols and hydroquinones. The k values also depend on the solvent nature and decrease by 6.5 and 50 times, on the average, when decane is replaced by toluene and acetonitrile, respectively. The logk values in decane, toluene, and acetonitrile depend linearly on the dissociation energies D OH of OH bonds in phenols and hydroquinones. Taking into account this dependence and using the experimental k value in acetonitrile, the estimate D OH = 346.6 kJ mol-1 was obtained for 2,5-dichlorohydroquinone. The thermodynamic parameters of formation of H-bonded complexes of phenols and hydroquinones with toluene and acetonitrile were calculated in the framework of the multiplicative approach to thermodynamic description of H-bonding. The rate constants k (free) of the reactions of the diphenylaminyl radical with free phenols and hydroquinones in toluene and acetonitrile were estimated. Comparison of the k (free) values with each other and experimental k values in decane suggests that the changes in k upon solvent replacement is mainly caused by the formation of H-complexes of phenols and hydroquinones with the solvent. Springer Science+Business Media, Inc. 2007.
