IT) 



The gaseous products are scrubbed to remove ethyl 

 alcohol and acetone, and the carbon dioxide is removed by 

 water under pressure, followed by dilute sodium hydroxide. 

 The residual hydrogen is converted into ammonia by 

 catalytic combination with nitrogen under pressure. A 

 recently developed alternative is to remove only three- 

 quarters of the carbon dioxide and to convert the remain- 

 ing mixture of carbon dioxide and hydrogen into methyl 

 alcohol by catalysis. The excess of carbon dioxide is 

 solidified and used for refrigeration. The solvents are 

 separated by fractional distillation. 



In the early stages of the fermentation acidity due to 

 the production of acetic and butyric acids develops, but 

 later falls again as the neutral products appear. If 

 acetic or butyric acids are added to a fermenting mash, 

 increased yields of acetone and but 3d alcohol, respectively, 

 are obtained. It is suggested that the butyl alcohol is 

 formed by reduction of butyric acid and that the acetone 

 arises from acetic acid via aceto -acetic acid which is 

 decarboxylated. The scheme is summarised by the 

 following equations given by Kluyver : — 



/OK 



(1) CeHiaOe > 2CH3.CO.C^OH (methylglyoxal hydrate). 



\h 



Glucose breaks down to give methylglyoxal hydrate, 

 probably by the same mechanism as in alcoholic fermenta- 

 tion. The methylglyoxal hydrate then splits to give 

 acetaldehyde and formic acid, which in turn yields 

 hydrogen and carbon dioxide : — 



