The kinetics and mechanism of the electrophilic substitution of heteroaromatic compounds. Part XXXII. Acid catalysed hydrogen exchange of azaindoles

Abstract

4-Aza-, 5-aza-, and 4-methyl-7-aza-indole each exchange the 3-proton, and the last compound also reacts at the 2- and 5-positions. 3-Aminopyridine undergoes hydrogen exchange at the 2-position and 4-methyl- and 6-methyl-2-aminopyridine each react at the 3- and 5-positions although at different rates. Rate constants are extrapolated to 100° and pH 0 and compared with similar data for other heterocycles to obtain quantitative estimates of relative reactivities.