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Mechanism and Linear Free Energy Relationships in Michael‐Type Addition of 4‐Substituted Anilines to Activated Olefin in Acetonitrile
Author(s) -
Dhahri N.,
Boubaker T.,
Goumont R.
Publication year - 2013
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.20811
Subject(s) - chemistry , hammett equation , acetonitrile , substituent , nucleophile , reaction rate constant , electrophile , olefin fiber , michael reaction , medicinal chemistry , dimer , free energy relationship , computational chemistry , stereochemistry , organic chemistry , kinetics , catalysis , physics , quantum mechanics
Kinetic studies for the Michael‐type reactions of ethyl‐3‐(4′‐ N , N ‐dimethylaminophenyl)‐2‐(nonafluorobutane)sulfonylpro‐penoate 1 with 4‐X‐substituted anilines 2a–e (X = OCH 3 , CH 3 , H, F, and Cl) have been investigated in acetonitrile at 20°C. A quadratic dependence of the pseudo–first‐order rate constants ( k obsd ) versus [ 2a–e ] has been observed and has been interpreted in terms of a dimer nucleophile mechanism. The finding of a relatively large negative ρ value (−3.09) for the Hammett plot suggests that the intermediate ( I ± ) is highly zwitterionic in nature. A linear correlation ( r 2 = 0.9989) between the Hammett's substituent constants σ and nucleophilicity parameters N of 4‐X‐substituted anilines in acetonitrile has been observed. The electrophilicity parameters E of the olefin 1 is evaluated, using the correlations σ versus N and log k versus σ and compared with the electrophilicities of analogously Michael acceptors.