Premium
Substituent effects on the reactions of aromatic triflones with para‐X‐anilines in methanol: Low intrinsic reactivity and transition state imbalances
Author(s) -
El Guesmi Nizar,
Boubaker Taoufik
Publication year - 2011
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20545
Subject(s) - chemistry , substituent , reactivity (psychology) , enthalpy , aniline , anisole , methanol , medicinal chemistry , marcus theory , kinetic energy , transition state , resonance (particle physics) , computational chemistry , reaction rate constant , kinetics , organic chemistry , catalysis , thermodynamics , medicine , physics , alternative medicine , pathology , quantum mechanics , particle physics
A kinetic study is reported for S N A r reactions of 2,4,6‐tris(trifluoromethanesulfonyl) anisole 1a with a series of para‐X‐substituted anilines 2a–e in a methanol solution at various temperatures. The substituent effects on free energy (Δ ≠ G ), enthalpy (Δ ≠ H ), and entropy (Δ ≠ S ) of activation are examined. Aniline addition to triflone 1a is characterized by a β X =0.57, α Z =0.31, and an imbalance of I = α Z –β X =−0.26. The imbalance shows that resonance development lags behind CN bond formation at the transition state. Interestingly, analysis of the results in terms of Marcus theory reveals that these S N Ar are associated with some extremely low intrinsic reactivity (log k o =−1.25& © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 255–262, 2011