Rate Measurements of the Hydrolysis of Complex Organic Macromolecules in Cold Aqueous Solutions: Implications for Prebiotic Chemistry on the Early Earth and Titan

Organic macromolecules (“complex tholins”) were synthesized from a 0.95 N₂ / 0.05 CH₄ atmosphere in a high-voltage AC flow discharge reactor. When placed in liquid water, specific water soluble compounds in the macromolecules demonstrated Arrhenius type first order kinetics between 273 and 313 K and produced oxygenated organic species with activation energies in the range of ∼60 ± 10 kJ mol⁻¹. These reactions displayed half lives between 0.3 and 17 days at 273 K. Oxygen incorporation into such materials—a necessary step toward the formation of biological molecules—is therefore fast compared to processes that occur on geologic timescales, which include the freezing of impact melt pools and possible cryovolcanic sites on Saturn's organic-rich moon Titan. Astrobiology 8, 273–287.