 Oro, Orgel and co-workers have shown that four molecules of HCN tetramerize to form diaminomaleodinitrile (12), which can be converted into almost all naturally occurring purines.For example, five molecules of HCN condense in an exothermic reaction to make adenine, especially in the presence of ammonia.The Traube purine synthesis (1900) is a classic reaction (named after Wilhelm Traube) between an amine-substituted pyrimidine and formic acid.