Catalyst-Free Gas-Phase Aldol Condensation of Hexanal: A Sustainable Pathway to 2-Butyl-2-Octenal

Aldol condensation reactions are pivotal in organic synthesis, enabling the formation of C-C bonds with broad applications in fine chemicals and fuel precursors. Traditional liquid-phase aldol condensations often require catalysts and harsh reaction conditions, which can complicate scalability and product isolation, and increase environmental impact. In contrast, gas-phase, catalyst-free aldol condensations present a promising, sustainable alternative, potentially minimizing the need for solvents and reducing operational costs. This study explores the self-condensation of hexanal under catalyst-free gas-phase conditions, leading to the formation of 2-butyl-2-octenal. By investigating the reaction mechanisms and optimizing the reaction environment, we demonstrate the feasibility of this approach, highlighting its potential for more efficient and eco-friendly synthesis of α,β-unsaturated aldehydes.