INDUSTRIAL FERMENTATIONS 313 



(3) to give acetic and formic acids : — 



CH3CO.COOH + HO.H > CH3COOH + HCOOH. 



The balance between the three modes of fermentation will 

 depend on the conditions prevailing. At a later stage in 

 the fermentation acetone and ethyl alcohol are formed 

 together, probably as a result of the condensation of 

 acet aldehyde to give aldol, 



2 CH3.CHO — > CH3CHOH.CH2.CHO, 



which then undergoes dismutation with a further molecule 

 of acet aldehyde to give p-hydroxybutyric acid and ethyl 

 alcohol : — 



CH3.CHOH.CH2.CHO O CH3.CHOH.CH2.COOH 



+ 11 — > + 



CH3.CHO H2 CH3.CH2.OH 



The p-hydroxybutyric acid undergoes an oxidation- 

 reduction with acetaldehyde to form acetoacetic acid 

 and ethyl alcohol : — 



CH3.CHOH.CH2.COOH CH3.CO.CH2.COOH 



CH3.CHO + CH3.CH2.OH 



Finally acetoacetic acid is decarboxylated with formation 

 of acetone : — 



Bakonyi has suggested that aldol undergoes an internal 

 oxidation and reduction and splitting to give acetic acid 

 and ethyl alcohol : — 



CH3CHOH.CH2.CHO ^ CHs-CHa.OH -r CH3.COOH 



Two molecules of acetic acid condense to give acetoacetic 

 acid which is then decarboxylated to give acetone and 

 Carlson dioxide : — 



(■H3.CUOH + CH^.COOK . ('H3.C0.('H,.(()()H i K.,i) 



CH3.CO.CH2.COOH > CH3.CO.CH3 + CO2 



