170 ABIOGENIC ORGANIC-CHEMICAL EVOLUTION 



For this reaction Az= — 21680 + 52-7T, which means that 

 it is thermodynamically possible up to 200° C. 



The next important reaction whicli methane can undergo 

 is that with ammonia and ammonium salts as follows: 



CH4 + NHg-^CHaNH, + 2H 



According to V. Dolgov^^ it is thermodynamically possible 

 for this reaction to take place at temperatures of 500° C and 

 higher, with the formation of methylamine. 



The chemical potentialities of ethylene and acetylene are 

 far wider. We must first discuss the various reactions in 

 which these compounds are hydrogenated and polymerised, 

 leading to the formation of saturated hydrocarbons, of higher 

 members of the olefine series, to ring formation into poly- 

 methylenes, and so forth. 



All these reactions are possible from a thermodynamic 

 point of view at temperatures below 500° C. 



The polymerisation of the gaseous olefines of low mole- 

 cular Aveight is accompanied by a decrease in volume. The 

 increased pressure in the lithosphere would, therefore, favour 

 its occurrence.''" 



The hydration of ethylene and acetylene is easily brought 

 about by their reaction with water. In the presence of specific 



catalysts such as AI2O3, W2O5 etc., the reaction C2H4-fH20 ^ 



C2H5OH can occur at temperatures of about 100° C if the 

 pressure is high.^^ 



Acetylene is hydrated by Kucherov's reaction to gi\e 

 acetaldehyde, C2H2 -1- H20->ch3CH0. This reaction occurs in 

 the presence of a number of catalysts ; even iron ore will 

 bring it about. The equation for its free energy is as follows: 



Az =- 35890 -H 29-5T -f 3-5/ (t/ 298- 16) 



and shows that it is thermodynamically possible for the 

 reaction to occur at temperatures of 900° C and below. 

 Acetylene can also be hydrated to form acetone : 



2C2H2 + 3H0O >CH3.CO.CH3 + COn + 2H2 



This reaction is usually carried out technically at tempera- 

 tures of 450- 470° C with the help of catalysts — oxides of 



