SONOMA STATE UNIVERSITY
Chemistry 336-Dale Trowbridge
Any modern Organic Chemistry text book will give a complete discussion of the currently accepted mechanism for the acid catalysed esterification of a carboxylic acid. In preparation for this experiment you should study this mechanism and include it in your prelaboratory write up. Synthesize your assigned ester by adapting the procedure given below for the preparation of isopentyl acetate to your individual starting materials.
PROCEDURE
Pour 10.0 ml of your assigned alcohol and a three fold molar excess of your assigned carboxylic acid into a 100 ml round-bottom flask. Carefully, with swirling add 2 ml of CONCENTRATED sulfuric acid to the contents of the flask. Add two boiling chips and heat the mixture to boiling under reflux for one hour.
Allow the mixture to cool to room temperature. Pour the cooled mixture into a separatory funnel and carefully add 30 ml of cold water. After gentle swirling, separate and discard the lower aqueous layer. Pour 15 ml of a 0.5 M sodium bicarbonate solution into the separatory funnel and shake the contents gently while venting to the funnel often to release the pressure due CO2 gas formed in this step. Discard the lower aqueous layer and repeat this extraction with another 15 ml portion of 0.5 M sodium bicarbonate solution. Continue doing these extractions until the lower aqueous layer is slighly basic. Wash the organic layer with 15 ml of concentrated salt solution and transfer the organic layer to a small Erlenmeyer flask. Add anhydrous magnesium sulfate to the crude ester and let it sit until it is clear (10-15 minutes).
Decant the liquid from the magnesium sulfate into a 25 ml round-bottomed flask and distill your product. Analyze your product for purity using glpc, and confirm its structure by ir, nmr, gcms and refractive index.