Premium
Kinetics of the reaction of 2‐chloro‐3,5‐dinitropyridine with meta ‐ and para ‐substituted anilines in methanol
Author(s) -
EL Hegazy Fatma ElZahraa M.,
Abdel Fattah Soheir Z.,
Hamed Ezzat A.,
Sharaf Saber M.
Publication year - 2000
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/1099-1395(200009)13:9<549::aid-poc297>3.0.co;2-5
Subject(s) - chemistry , methanol , nitro , kinetics , nucleophilic aromatic substitution , hydrogen bond , medicinal chemistry , reaction rate constant , computational chemistry , stereochemistry , nucleophilic substitution , organic chemistry , molecule , alkyl , physics , quantum mechanics
The kinetics of the reaction of 2‐chloro‐3,5‐dinitropyridine ( 1 ) with meta ‐ and para ‐substituted anilines ( 2a–j ) to give 2‐anilino‐3,5‐dinitropyridine derivatives ( 3a–j ) were studied in methanol at different temperatures. IR studies of the products ( 3a–j ) indicated the presence of hydrogen bonding between N—H and an o ‐nitro group, and UV spectra showed a red shift resulting from the interaction between an amino group and aza and nitro groups. A plot of Δ H ‡ versus Δ S ‡ gave a good straight line with a 324 °C isokinetic temperature. Good linear relationships were obtained from plots of log k 2 against σ values at all temperatures with relatively large negative ρ values (−3.75 to −3.16) indicating the formation of a Meisenheimer σ‐complex intermediate. Plots of log k 2 against p K a values (β = 0.85) gave good straight lines at 25 °C, except for 2f (4‐COCH 3 ), indicating that the reactions involve a significant bond formation in the transition state. An S N Ar mechanism is suggested to proceed via two stages, with the first being rate determining. Copyright © 2000 John Wiley & Sons, Ltd.