Hydrothermal processing of organic molecules produced by gas-grain reactions under nebular conditions

Gas-grain reactions under nebular conditions carried out in the laboratory yield simple organic molecules, such as saturated and unsaturated hydrocarbons and thiols, as well as polymeric residues and mineral phases similar to those reported in interplanetary dust particles. Here, the subsequent alteration of this organic materials under hydrothermal conditions, which have been likely to occur in some asteroids and comets, is experimentally addressed. It has been found that the transformation of alkenes to alcohols and carboxylic acids and that of thiols to sulfonic acids takes place at 375-575 K and 10-100 kPa in the presence of phyllosilicates similar to those found in CI and CM carbonaceous chondrites. The transformation of the original organic molecules is not effective over metallic surfaces, crushed ordinary chondrites, and CV carbonaceous chondrites.