The kinetics and mechanism of the electrophilic substitution of heteroaromatic compounds. Part 49. Correlation of standard rates for hydrogen exchange and nitration of heteroaromatic compounds

Abstract

Acid-catalysed deuteriodeprotonation rates are recorded for uracil, 1,3-dimethyluracil, 2,6-dimethoxypyridine, 4-dimethylaminopyridine, and cinnoline. The rates are extrapolated to give standard rate constants at 100 °C and H₀ 0 and also at 25 °C 75% H₂SO₄. Use of the latter conditions, i.e. those previously selected to determine standard nitration rates, give less scatter in a direct comparison with the standard nitration rates. Although the absence of a unique linear relationship is clearly demonstrated, the use of identical standard conditions discloses very good partial linear correlations for substrates of closely related structure.