The prebiotic synthesis of acrolein

Acrolein is a central intermediate in the prebiotic synthesis of several amino acids, pentaerythritol, as well as various postulated alternative genetic materials. Acrolein is highly reactive so that its steady-state concentration could not have been very high. The ease of synthesis of acrolein from the aqueous aldol condensation of acetaldehyde and formaldehyde was therefore of interest. It is shown here that acrolein is produced in a low, but significant, steady-state concentration from very dilute solutions of formaldehyde and acetaldehyde under neutral to basic conditions. Acrolein is produced under conditions that are too dilute for the oligomerization of formaldehyde to produce carbohydrates. The implications of these findings for prebiotic chemical evolution are discussed.