Prebiotic adenine synthesis via HCN oligomerization in ice.

Adenine is produced (after hydrolysis) when 0.01 M solutions of HCN are adjusted to pH 9.2 with NH4OH and are frozen at -2 degrees C for 60-100 days. The addition of glycolonitrile (the cyanohydrin of formaldehyde) increases the yield of adenine under these conditions by about five-fold. These results confirm and extend an earlier suggestion that purine synthesis on the prebiotic Earth might have occurred in frozen, dilute solutions of HCN.