Co-production of butyrate methyl ester and triacetylglycerol from tributyrin and methyl acetate

The simultaneous synthesis of butyric acid methyl ester, the shortest component of the FAME (fatty acid methyl esters) family, and glycerol triacetate (TAG) from glycerol tributyrate (tributyrin) and methyl acetate was studied as a function of several reaction parameters, such as type of catalyst, temperature and products distribution. The reaction is an interesterification, a multistep consecutive ester interchange catalyzed by either acid or base catalyst. Under optimized conditions, a complete tributyrin conversion and an almost quantitative butyric acid methyl ester accumulation were achieved. The other reaction product, TAG, formed by the complete acetylation of the glycerol moiety, reached almost 70% yield, whereas the mono- and di-acetylated intermediates accumulated in the order of 5–8% and 24–27%, respectively. Similar final conversions and products yields were obtained with either acid or base homogeneous catalysts, suggesting that the final products mixture did not depend on the type of catalysis but might be limited by equilibrium conditions. In spite of similar final yields, base catalysis needed shorter reaction times (minutes instead of hours) and lower temperature (60 °C instead of 130 °C) with respect to the best acid catalyst. On the other hand, unlike heterogeneous basic catalysts, which showed low activity, a heterogeneous acid catalyst almost as active as the homogenous counterpart was found.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (92 K)Download as PowerPoint slideResearch highlights▶ Simultaneous synthesis of butyrate methyl ester, BuMe, and glycerol triacetate, TAG. ▶ Synthesis of biofuel (BuMe) and diesel-compatible glycerol derivatives. ▶ Quantitative yield of BuMe and 70% selectivity on TAG. ▶ Similar final products yields with either acid or base catalysts.