Selective production of 1,3-butadiene using glucose fermentation liquor†
The production of 2,3-butanediol from glucose fermentation products and its subsequent esterification and conversion to 1,3-butadiene is reported. The addition of formic acid and acetic acid (C1–C2 acids) to the esterification reaction mixture resulted in yields of the diesters of 70% and 85%, without the loss of C1–C2 acids during the reaction. In the pyrolysis step, a highly selective (94% and 82% for formic acid 2-formyloxy-1-methyl-propyl ester and acetic acid 2-acetoxy-1-methyl-propyl ester, respectively) C–O cleavage to 1,3-butadiene over diesters was achieved without a catalyst. In the case of acetic acid, 100% was recovered, whereas in the case of formic acid, only 20% was recovered. Based on these results, it can be concluded that using glucose fermentation liquor as the starting material with external addition of acetic acid (2,3-butanediol : formic acid : acetic acid = 1 : 0.5 : 2.5), 70% yield of 1,3-butadiene can be achieved where the loss of formic acid is compensated by the acid in the starting material.