Conversion of Adipic Acid to Bis-2-ethylhexyl Adipate Overcoming Equilibrium Constraints: A Laboratory Experiment

An adipic acid esterification experiment suitable for graduate students has been developed to describe the industrial manufacture of plasticizers. Students first follow the progress of the reaction with simple acid/base titration enabling measurement of the acid number. During the workup of the reaction mixture, they learn how to manage the filtration of a viscous mixture over an inert support such as Celite and practice on atmospheric and vacuum distillations. They finally learn to set a mass balance on 2-ethylhexanol using fully experimental data from their own reactions. To this end, they also learn how to retrieve from a [superscript 1]H NMR spectrum the required data to evaluate the purity and the yield of bis-2-ethylhexyl adipate. These tasks corroborate basic concepts related to the tools available to shift the equilibrium in reversible reactions, at the same time providing new knowledge on mass balance calculations and [superscript 1]H NMR.