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.