Question

9. Then add slowly while mixing 1 mL of saturated sodium bicarbonate solution (NaHCO3) -IT WILL BUBBLE! Add additional drops of saturated sodium bicarbonate solution with mixing until no additional bubbling occurs Congratulations! You have just made your first ester. Now you want to separate your ester product from the other stuff in the reaction mixture. CTQ3 Sodium bicarbonate is a base. How will it interact with any carboxylic acid molecules still present in your reaction mixture? 10. Add 1mL (20 drops) saturated NaCl solution, mix and then add 2 ml pet. ether (you can do a pipet full of pet either, this does not need to be precise). Mix again and let two layers form. CTQ4 What are the dominant intermolecular forces (IMFs) of each layer? Which would you expect to dissolve the ester with the ester formed in the reaction and why? Hint: think about the number of carbon atoms. 11. Place your Pasteur pipet through the layers to the bottom of the test tube while expelling air and draw up the salt water layer. Put the water layer you just removed into a beaker for later disposal. NOTE: be sure you don't dispose of the water until you are sure you've isolated the ester in case you have accidentally taken the wrong layer. 12. Repeat that procedure until the all the water is removed. Leave a little bit of water if necessary since you'll be adding more water in the next step anyway. 13. Add 1 ml of the saturated NaCl solution to the pet ether again, mix gently and let two layers separate. The salt water will be again on the bottom. Again remove as much of the bottom layer as possible and place it in your waste beaker for later disposal. If you lose a little of the ester in the process that is fine. It is better to err on the side of removing ALL water at this point. CTQ5 In addition to Na', cr and water, what other substances are likely in the bottom layer you're discarding? 14. Transfer all of the ether to a fresh test tube. If you see layers in the pipet when you suction out the last bit of ether, be sure to discard the bottom layer in your water waste. 15. Get rid of the remaining water by using the drying agent MgSO4 (absorbs water strongly). Add a small amount (spatula tip) of anhydrous MgSO. and swirl to remove any remaining H20. The water will be part of the solids below. Be sure to continue adding until the MgSO. is no longer clumping 16. Using a pipet, draw off the pet ether solution from above the solids and transfer this to a clean (labeled) vial and use the rotary evaporator to remove the excess pet ether. Be careful not to evaporate your ester, which should remain as a colorless liquid. Shp S2 Step Figure 5.16 Pasteur Pipet CTQ 6 Based on the physical properties of esters, why do separation of two immiscible liquid you think it's helpful to keep your esters covered phases, the less dense layer contains as much as possible when outside of the hood? the product 17. Get a breath of fresh air to clear your nasal receptors and then try smelling the ester describe thearoma