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Reactions of Hydroxypyridines with 1‐Chloro‐2,4,6‐trinitrobenzene − Product Structure, Kinetics, and Tautomerism
Author(s) -
Boga Carla,
Bonamartini Anna Corradi,
Forlani Luciano,
Modarelli Vincenzo,
Righi Lara,
Sgarabotto Paolo,
Todesco Paolo Edgardo
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200103)2001:6<1175::aid-ejoc1175>3.0.co;2-6
Subject(s) - chemistry , picrate , tautomer , pyridine , medicinal chemistry , nucleophile , ether , diphenyl ether , nitrogen atom , ring (chemistry) , benzimidazole , nitrogen , organic chemistry , catalysis , ion
Reactions between 1‐chloro‐2,4,6‐trinitrobenzene and 2‐hydroxypyridine, 3‐hydroxypyridine, and 4‐hydroxypyridine are reported. 4‐Hydroxypyridine produces the product of attack at the nitrogen atom, while 3‐hydroxypyridine reacts at the oxygen atom. 2‐Hydroxypyridine reacts as an ambidentate nucleophile, providing a mixture of products arising from attack at both the oxygen and the nitrogen atom. Reactions between X‐substituted‐3‐hydroxypyridines (X = H, 5‐Cl, 6‐CH 3 ) and 1‐chloro‐2,4,6‐trinitrobenzene provided 3‐pyridinyl 2,4,6‐trinitrophenyl ethers, analysed by 1 H and 13 C NMR spectra and by X‐ray diffraction. Moderate heating of methanolic solutions of 3‐pyridinyl 2,4,6‐trinitrophenyl ether and of 6‐methyl‐3‐pyridinyl 2,4,6‐trinitrophenyl ether caused a methylation reaction of the pyridine nitrogen ring through trinitroanisole, providing 3‐hydroxy‐1‐methylpyridinium picrate and 1,2‐dimethyl‐5‐hydroxypyridinium picrate. Kinetic data are compared and discussed.