STRUCTURAL EFFECT ON THE MECHANISTIC PATHWAY OF THE DECOMPOSITION OF 3-ALKYL-1-ARYLTRIAZENES: A KINETIC STUDY
A kinetic study of the reaction between 3-alkyl-1-aryltriazenes and substituted acetic acids has been made in solvent acetone over the temperature range 21-37 deg C.Ea is 17.3 +/- 0.3 kcal mol-1 and log A is 10.3 +/- 0.1.Influence of the substituents on the reaction rate has been analyzed.The Hammett correlation with ? gave a ρ value of -0.96 for para-aryl substituted triazenes and +0.35 for meta- and para-substituted phenylacetic acid.The rate of decomposition of triazenes is also affected by changing the alkyl group.From these results a duality in mechanism is proposed; first, a simultaneous protonation and alkyl group expulsion to be the rate-determining step when R is tertiary, benzylic and possibly secondary.Secondly, a concerted mechanism for the protonation of nitrogen and cleavage of the N-R bond for primary alkyl groups.
Laila, Abdulhameed A. R.
p. 453 - 456
(2007/10/02)
Substituent Effects on 13C and 15N Chemical Shifts in Triazenes Studied by Principal Components Multivariate Data Analysis
Principal components analysis was applied to the 13C and 15N chemical shift data on a series of fifteen 1-(para-substituted-phenyl)-3-acetyl-3-methyltriazenes.It was found that the halogen-substituted triazenes formed a class, based on substituent effects, which was different from the remaining eleven triazenes.A one-component model described the halogen class, whereas a two-component model was necessary for a description of the second class.In the second class, substituent tended to cluster to form groups depending on their electronic character.
Dunn, III, W.J.,Lins, C.,Kumar, G.,Manimaran, T.,Grigoras, S.,et al.
p. 450 - 456
(2007/10/02)
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