Abstract Free radicals are important reactive species that perform both positive and negative functions within living organisms. Antioxidants play a significant part in preventing or managing diseases linked to oxidative stress, including cancer, cardiovascular disease, and neurodegenerative disorders. In the presented work, a two-step synthesis was used to prepare 15 phenolic compounds substituted with various N -heterocyclic moieties as potential antioxidants. The starting materials were 4-hydroxyphenylalkyl ketones, which were converted into 4-hydroxy-3-chloromethylphenylalkyl ketones via chloromethylation. These then reacted with various aliphatic amines (dimethylamine, diethylamine, isopropylamine, isobutylamine, and tertbutylamine) and heterocyclic amines (pyrrolidine, piperidine, morpholine, azepane, and 4-methylpiperazine). The purity of the products was confirmed by thin-layer chromatography, and their infrared (IR), ultraviolet (UV), and proton nuclear magnetic resonance ( 1 H NMR) spectra were measured. Their antioxidant activity was determined using the DPPA and ABTS methods. The ABTS results show antioxidant activity values ranging from 85% to 95%, which are higher than the values for oxygen derivatives. Conformational analysis revealed a stronger hydrogen bond between OH and N than between OH and O. In the case of the compound containing isobutyl, the formation of an intramolecular hydrogen bond (NH⋯O) is considered more likely.
Cizmáriková et al. (Mon,) studied this question.