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

摘要

Organic macromolecules ("complex tholins") were synthesized from a 0.95 N_2/0.05 CH_4 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.