Study on the Demethylation Reaction of 1,4-naphthoquinones

Abstract

Naphthoquinones affect many biological processes. Knowing their reactivity is vital in truly understanding these processes as well as making a variety of biochemical relationships. Here we study the reactivity of 2-bromo-3-methyl-1,4-naphthoquinone as well as 2-chloro-3-methyl-1,4-naphthoquinone with various alkylamines. Bromine and chlorine as a substituent are considered good leaving groups and therefore, we anticipated the alkylamines to substitute them. We have found that this is not the case. The alkylamines replace the methyl group through a demethylation process instead. The acidic nature of ɑ-methyl hydrogen is suggested to induce this demethylation process. In the case of 2-chloro-3-methyl-1,4-naphthoquinone, two products are concurrently formed with both the methyl and the chloro sites substituted. The major product is the demethylated one, 2-alkylamino-3-chloro-1,4-naphthoquinone.