Methanol attack on highly electrophilic 4,6-dinitrobenzofurazan and 4,6-dinitrobenzofuroxan derivatives. A kinetic study

Abstract

scribed previously.1 NaOH solutions were prepared from Titrisol.Kinetic determinations were made on a Durrum stopped-flow spectrophotometer, the cell compartment of which was maintained to ±0.5 °C. All runs were carried out under first-order conditions with a substrate concentration of about 5 X '6 M. Rate constants are considered accurate to ±3%.Acknowledgment. The authors thank the North Atlantic Treaty Organization for a grant (NATO Res. 1540) to F.T. and M.J.S. supporting this research.

Substituent effects on the reactions of aromatic triflones with para‐X‐anilines in methanol: Low intrinsic reactivity and transition state imbalances

“…• C [27]. Our results show that the replacement of NO 2 by SO 2 CF 3 is accompanied by an appreciable decrease in intrinsic reactivity ( log k o = −0.70).…”

S N Ar Reactions of Amines in Aprotic Solvents

“…The identification of the open intermediates 16 constitutes a strong indication to suggest that the conversion of 2-halo-5-nitropyridines into the corresponding 2-hydroxypyridines occurs via the S N (ANRORC)-type process rather than via the anticipated S N Ar mechanism. The feasibility of nucleophilic substitutions at the 4-or 7-position in condensed heterocycles such as nitrobenzofurazans has been also recently proved, and the finding of -adducts of the type found in trinitrobenzene analogues gives strong support to the operation of similar mechanisms 17 . Nevertheless, the observation of by-products indicates that nucleophilic attack also occurs at the annelated moiety with destruction of the heterocyclic system.…”

A new feature in the chemistry of nitrobenzofuroxans: ambident reactivity in Diels–Alder condensations

“…6 The same principle applies in all reported interactions of DNBF with oxygen, nitrogen or sulfur nucleophiles. 1,3,4,[8][9][10] Interestingly it has been argued that the low aromatic character of the benzofuroxan system should be one of the major factors responsible for the exceptional electrophilic reactivity of DNBF and nitrobenzofuroxans in general. 1,2,9 Should this be true, the idea that these compounds might be involved in Diels-Alder type reactions under some experimental conditions could not be excluded.…”