This question is based on the esterification reaction of ethyl laurate 1.After t

Question

This question is based on the esterification reaction of ethyl laurate

1.After the reaction mixture is heated at 120 degree C for 1 h, it is concentrated to 0.25 mL before adding Sodium bicarbonate and Ether solutions. What happens if you do not concentrate?

200 CHAPTER 6 Microscale Organic Laboratory Experiments Reagents and Equipment. Weigh and add 70 mg (0.35 mmol) of lauric to a 3.0-mL conical vial containin id g a magnetic spin vane. Then equip the reaction be vial with a reflux condenser that is protected by a calcium chloride drying tu (+). Use a graduated 1.0-mL pipet to add 1.0 mL of absolute ethanol to the vial. In the hood, add 30 L (0.43 mmol) of acetyl chloride, usingan automati delivery pipet. (Remember not to turn on the cooling water in the condenser until the system is completely assembled. Otherwise, the cold inner surface HOOD will condense moisture from the laboratory atmosphere. It takes only small amount of water on the condenser walls to completely deactivate your 110-120 °C thermometer acid chloride catalyst CAUTION: Acetyl chloride is an irritant. Dispense this reagent in the HOODhood using an automatic delivery pipet. (Be sure to quickly reassem ble the reaction vial and f the acid chloride, because this reagent will rapidly react with moist laboratory condenser following addition o air and lose its activity.) Speed Heat Lauric acid, 70 mg + CH3CH20H, 1.0 mL + CH3COCI, 30 Reaction Conditions. Heat the reaction mixture for 1 h at gentle reflux with stirring, using a sand bath temperature of 110-120 °C. Cool the resulting mix ture to room temperature Isolation of Product. After removing the reflux condenser and drying tube, re move the spin vane with forceps. Add a boiling stone to the cooled vial and then concentrate the reaction solution to a volume of about 0.25 mL by warming in a sand bath in the hood. Remove the vial from the sand bath and allow the vial to cool. Use a 1.0-mL graduated pipet to add 0.5 mL of diethyl ether and 0.25 mL of 5% sodium bicarbonate solution to the concentrated product mixture. Cap the HOOD p carefully to vent the two-phase mixture. Remove the bottom aqueous layer using a Pasteur filter pipet and set it aside in a labeled Erlenmeyer flask. Extract the ether phase with three additional 025-mL portions of 5% sodium bicarbonate solution. Save the aqueous wash after each extraction (you may combine them with the initial aqueous basic phase in the Erlenmeyer) and do not discard them until you have successfully purified and characterized the ethyl laurate.

Explanation / Answer

CH3(CH2)10OOH + C2H5OH --> CH3(CH2)10OOC2H5 + H2O

During the reaction, water is produced. It is is cooled and then concentrated to prevent emulsions and remove water from the mixture respectively.

Since water is miscible in both aqueous phase (sodium bicabonate solution) and organic phases (diethyl ether) , it interferes in product purification by extraction process.

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