1. Chapter 40 Esterification. Synthesis of n-Butyl Ester of Unknown Acid by Azeotropic Distillation of Water

2. Purpose In this experiment an Unknown carboxylic acid is esterified with butanol in the presence of an acid catalyst in an azeotropic distillation mode.In this experiment an Unknown carboxylic acid is esterified with butanol in the presence of an acid catalyst in an azeotropic distillation mode. The product is isolated by:The product is isolated by: 1)withdrawing the reaction mixture from reaction flask with a Pasteur pipette to leave the catalyst behind and 2) extraction with aqueous NaHCO 3 solution and ether.

3. Reaction Mechanism The mechanism involves initial protonation of CO 2 H group, attack of the nucleophilic OH, a proton transfer, and loss of H 2 O followed by loss of the catalyzing proton to give an ester.The mechanism involves initial protonation of CO 2 H group, attack of the nucleophilic OH, a proton transfer, and loss of H 2 O followed by loss of the catalyzing proton to give an ester.

4. Comments Follow pp. 559-560 (microscale).Follow pp. 559-560 (microscale). Follow the lab handout for all experimental procedures.Follow the lab handout for all experimental procedures. Unreacted acid should be removed by washing reaction mixture with aqueous NaHCO 3 with following extraction.Unreacted acid should be removed by washing reaction mixture with aqueous NaHCO 3 with following extraction. Perform IR and GC/MS analysis of the product. Prepare sample for NMR.Perform IR and GC/MS analysis of the product. Prepare sample for NMR. Determine the structure of the Unknown acid from spectral data.Determine the structure of the Unknown acid from spectral data. Calculate yield. High to moderate yields should be achieved.Calculate yield. High to moderate yields should be achieved.

5. Safety Flammable reagents are used in this experiment, keep away from open flame.Flammable reagents are used in this experiment, keep away from open flame. Acids are corrosive, avoid contact with skin and eyes.Acids are corrosive, avoid contact with skin and eyes. Caution: Note ‘fruity’ fragrance of the final product (use wafting, do not inhale!). n-Butyl acetate can cause irritation of eyes, upper respiratory system and skin.Potential symptoms of overexposure are headache, drowsiness, narcosis. Do not inhale, avoid contact with skin and eyes.Caution: Note ‘fruity’ fragrance of the final product (use wafting, do not inhale!). n-Butyl acetate can cause irritation of eyes, upper respiratory system and skin. Potential symptoms of overexposure are headache, drowsiness, narcosis. Do not inhale, avoid contact with skin and eyes.