Isolation and FTIR Characterization of Nitrogen-Rich Condensation Products from the Allantoin–Dicyandiamide System

This study investigates the acid‑catalyzed condensation between allantoin and dicyandiamide, focusing on the structural identification of nitrogen‑rich intermediates and final products. The reaction system was examined under controlled reflux conditions, allowing the isolation of two major fractions, designated LG‑5A and LG‑5B. FTIR spectroscopy was applied as the primary analytical technique to evaluate functional‑group transformations, including shifts in carbonyl, amide, imide, and guanidine‑related bands. LG‑5A demonstrated sharper, well‑defined peaks, suggesting a more ordered condensation product, while LG‑5B exhibited broader absorptions, consistent with higher hydrogen‑bonding or partial unreacted material. The results support a mechanism in which dicyandiamide undergoes nucleophilic addition to the ureido carbonyl of allantoin, followed by dehydration and formation of extended C–N conjugation. These findings contribute to a deeper understanding of urea‑ and guanidine‑based frameworks, which are relevant in polymer science, functional materials, and nitrogen‑rich compound design.