DFT study of gas phase acid-catalyzed ethanolysis of butyric acid triglyceride

► DFT calculations showed a concerted mechanism for the reaction under study. ► Transesterification occurs first on the center ester bond (C-2). ► Intramolecular H bond between the acid proton and oxygen of the glycerol backbone. ► Carbonyl carbon weakly bound to the both oxygen of the incoming and leaving groups.