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Ambident electrophilicity of 4‐nitrobenzochalcogenadiazoles: Kinetic studies and structure‐reactivity relationships
Author(s) -
Necibi Feriel,
Salah Saida Ben,
Roger Julien,
Hierso JeanCyrille,
Boubaker Taoufik
Publication year - 2020
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.21391
Subject(s) - chemistry , electrophile , nucleophile , reactivity (psychology) , reaction rate constant , medicinal chemistry , adduct , computational chemistry , kinetics , hammett equation , substitution reaction , stereochemistry , organic chemistry , catalysis , medicine , physics , alternative medicine , pathology , quantum mechanics
The kinetics of the reactions of 4‐nitrobenzofurazane 1a , 4‐nitrobenzothiadiazole 1b , and 4‐nitrobenzoselenadiazole 1c with a series of 4‐Y‐substituted phenoxide anions 2a‐e (Y = OMe, Me, H, Cl, and CN) in aqueous solution at 20°C were investigated photometrically. The derived second‐order rate constants ( k 2 ) have been combined with the nucleophilicity parameters values of these series of anions 2a‐e to determine the electrophilicity parameters E of electrophiles 1a‐c according to the linear free‐energy relationship (log k 2 )/ s versus N . General reactivity of these electrophiles 1a‐c is found to be fairly similar with E values ranging in −10.77 ± 0.61 < E < −7.53 ± 0.29. The comparison with structurally related neutral electron‐deficient heteroaromatic and aromatic compounds revealed that 1a ‐ c are more reactive than 1,3,5‐trinitrobenzene, as benchmark aromatic electrophile used in nucleophilic addition or substitution processes. The rate constants for the reactions of 4‐nitrobenzochalcogenadiazoles 1a‐c with some other nucleophiles were measured and found to agree with those calculated from Mayr's equation. Finally, analysis of the rate data in terms of the Brønsted approach reveals that 1a‐c exhibits especially low intrinsic reactivity in σ‐adducts 3 forming reactions.