1. Which solvent used in the isolation of methyl benzoate is highly flammable?
2. Which main reactant(s) is of renewable feedstock?
3. Explain the role in this experiment (a) methanol (b) 95% ethanol
Preparationof MethyBenzoote Needle in septum to relieve pressure ã¼ 1. Set up and turn on a sand bath (set simmer- Condenser wrapped with wet stat at 6) before doing anything else. paper towel and pipe cleaner Connector & support rod 5 mL round bottom flask in 2. Weigh 0.5 g benzoic acid into a 5 ml round bottom flask. Add 2 boiling chips. Add 2.5 mL methanol and swirl to dissolve. Add 0.1 mL (4-5 drops) c. sulfuric acid and swirl to mix. Reflux the mixture while you make and recrystallize the ASA. NB keep the condenser jacket wet throughout the reflux. 3. 4. heating mantle Micro reflux set-up At the end of the reflux, cool the reaction mixture and transfer it to the conical tube; add 5 ml water 5. Rinse the reaction flask with 4 mL ether and add to the conical tube. Mix well. [initially your product will be an oil bubble at the bottom of the test tube. Upon mixing, it should dissolve in the ether and be in the top layer.] Remove the water with a Pasteur pipette. Add a fresh 5 mL aliquot of water, mix well, and remove the water. 6. 7. Carefully add 2 mL saturated sodium bicarbonate solution with mixing (CO, bubbles evolve) to the ether layer. Remove the aqueous layer and add a second 2 mL aliquot of sat. NaHCO3. Mix until intense bubbling stops; check the pH of the aqueous layer, it should be 9 (pH paper green/blue). Remove the aqueous layer, and wash the organic layer with 2mL saturated Nad. Remove the NaClã 8. 9. Transfer the ether layer into a clean, dry test tube, using a clean, dry dropper. Add 3 -4 CaCl2 pellets. Tilt the test tube at a 45° angle and rotate carefully. If the CaCl2 pellets stick together, pour the ether layer into another dry test tube and add 3-4 new CaCl2 pellets. (You may need to repeat this drying procedure 3 or 4 times). When pellets float freely and don't stick to the glass, the ether is dry. 10. Transfer the dry ether layer to a pre-weighed, dry test tube, and carefully drive off the ether with a gentle stream of compressed air. The product should be a clear, sweet smelling, viscous liquid. Weigh test tube and contents to determine yield. 11. Use 1 drop of the clean, dry product to run an IR spectrum. Use product scent, viscosity, and IR data to verify that ester was made. Note: if you do not evaporate all the ether, the product will be runny rather than viscous, will smell of ether, and the yield will be suspiciously high 12. Show your products to your demonstrator, tell him/her the weight, then discard it into the flammable waste collector. 83
