- STRUCTURAL EFFECT ON THE MECHANISTIC PATHWAY OF THE DECOMPOSITION OF 3-ALKYL-1-ARYLTRIAZENES: A KINETIC STUDY
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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.
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p. 453 - 456
(2007/10/02)
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- Pathways for the Decomposition of Alkylaryltriazenes in Aqueous Solution
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Primary alkylaryltriazenes give solvent-equilibrated alkenediazonium ions and anilines in aqueous solution at 25 deg C by two processes.The first, an A-SE2(N) reaction, involves immobilisation of a molecule of catalysing acid, and a transition state in which the proton is essentially completely transferred and little breakage of the N-N bond has occurred.The structure of this transition state varies with the strength of the catalysing acid and the pKa of the liberated aniline in a way interpretable in terms of a More O'Ferrall-Jencks diagram.The second process is the departure of aniline anion without acid assistance.The first process is governed by positive, the second by negative, βlg values.
- Jones, Caroline C.,Kelly, Migel A.,Sinnott, Michael L.,Smith, Paul J.,Tzotzos, George T.
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p. 1655 - 1664
(2007/10/02)
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