Review on the Synthesis and Biological Activities of Glycolaldehyde and Its Dimer

Glycolaldehyde, a simplest α-hydroxyaldehyde, exists in a complex equilibrium of monomer, hydrate, and dimer forms a solution. Its dimer, 2,5-dihydroxy-1,4-dioxane, possesses a stable chair conformation with axial hydroxy groups in the solid state. While glycolaldehyde is known to be highly reactive and can form advanced glycation end products (AGEs) related to oxidative stress, its dimer is drawing attention as a valuable building block in organic synthesis. This review explores the structural features, biological activities, and synthetic methods of glycolaldehyde and its dimer. Novel applications for the synthesis of a new renewable thermoplastic (PDHDO), catalytic oxidation to glycolic acid, its use in Passerini-Ugi multicomponent reactions and antimicrobial activities highlight its potential as a promising intermediate in medicinal chemistry and sustainable polymer science. Further research on stabilizing the dimer structure and controlling its reactivity is expected to expand its industrial applicability.