"On-Water" Interfacial Acidification Enhances Direct Ammonolysis of Triglycerides

Direct ammonolysis of triglycerides with liquid ammonia is a well-established technology for the industrial manufacture of aliphatic amides typically requiring a large excess of ammonia. In this study, using glyceryl trilaurate (GTL) as a model triglyceride, we demonstrate that the rate of lauramide formation can be enhanced sevenfold at 150 °C and low ammonia excess (47:1 mol/mol ammonia/GTL) when the reaction is carried out in GTL-in-water(acetonitrile) (50:50 v/v) emulsions stabilized by surface-active Aquivion perfluorosulfonic superacid (PFSA) particles, compared to a non-emulsified system. Moreover, the lauramide yield after 5 h is nine times higher than that achieved with conventional ammonolysis in liquid ammonia at higher ammonia excess (148:1 mol/mol ammonia/GTL). This significant increase in activity is attributed to the "on-water" selective acidification at the microstructured oil-water interface facilitated by adsorbed Aquivion PFSA particles, in combination with enhanced ammonia solubilization and selective glycerol extraction by the water(acetonitrile) phase.