178 ABIOGENIC ORGANIC-CHEMICAL EVOLUTION 



a mixture of benzene and carbon monoxide to benzaldehyde 

 and so forth. 



Acetaldehyde and its condensation products are formed 

 from mixtures of acetylene and water under such conditions. 

 If a mixture of benzene and water is submitted to an electric 

 discharge phenol will be formed. 



Carbon monoxide can also react directly with hydrogen 

 to give formaldehyde. This reaction is brought about by 

 electric discharges, though only to a very small extent."^ 



Reactions between hydrocarbons and their derivatives and 

 ammonia must also have occurred extensively in the primi- 

 tive atmosphere. In this connection we must first discuss the 

 reactions by which hydrocyanic acid is formed: 



CH4 + NH3->HCN + 3H2 — 60 kcal 



C2H4 + 2NH3->2HCN + 4H2 63 kcal 



C2H2 + 2NH3->2HCN + 3H2— 28 kcal 



CO + NHj-^HCN -f HoO — 1 o kcal 



These reactions are all endothermic but they proceed 

 satisfactorily when an electric discharge passes through a 

 mixture of the gases. ^°^ Hydrocyanic acid is also formed in 

 this way in mixtures of hydrocarbons and molecular nitro- 

 gen. This latter could have arisen in the primitive atmo- 

 sphere by the oxidation of ammonia by the free oxygen 

 derived from the photolysis of water. Long ago, Berthelot 

 showed that hydrocyanic acid was synthesised at the expense 

 of molecular nitrogen when this was mixed with acetylene 

 and submitted to arc"^ or flash^"* discharges. H. Becker 

 showed later that a similar process may take place with silent 

 discharges. ^°^ 



One of the many products of such discharges in a mixture 

 of nitrogen, carbon monoxide and hydrogen is urea.^" This 

 is probably formed by a reaction between carbon monoxide 

 and ammonia, the ammonia having previously been formed 

 from hydrogen and nitrogen. 



No + SHo-^QNHg 

 2NH3 + CO->NH2.CO.NH2 -f H2 



Reactions between hydrocarbons and hydrocyanic acid or 



