A modified water-immiscible
solvent useful in the extraction of
acetic acid from aqueous streams is a substantially pure mixture of isomers of highly branched di-
alkyl amines. This
solvent is substantially devoid of mono-
alkyl amines and alcohols.
Solvent mixtures formed of such a modified
solvent with a desired cosolvent, preferably a low boiling
hydrocarbon which forms an
azeotrope with water are useful in the extraction of
acetic acid from aqueous gaseous streams. An anaerobic microbial
fermentation process for the production of
acetic acid employs such solvents, under conditions which limit
amide formation by the solvent and thus increase the efficiency of acetic acid
recovery. Methods for the direct extraction of acetic acid and the extractive
fermentation of acetic acid also employ the modified solvents and increase efficiency of acetic
acid production. Such increases in efficiency are also obtained where the
energy source for the microbial
fermentation contains
carbon dioxide and the method includes a
carbon dioxide stripping step prior to extraction of acetic acid in solvent.