Preparation of Methyl Salicylate (Oil of Wintergreen) from Aspirin

Write lab(Methyl Salicylate (Oil of Wintergreen) Results and Discussion and Conclusion

Results and Discussions: Results: yield, percent yield,IR, NMR etc. Discussions: analysis of spectrum, identities and purities of the product, percent yield of the product etc. Conclusions References

Revised 2-13-12 Preparation of Methyl Salicylate (Oil of Wintergreen) from Aspirin (Instructions for Section 1) 1st period Into a 25-mL round bottom flask (from your semi-micro kit), transfer between 1 and 1.5 grams of the aspirin you prepared previously. Use the analytical balance, and record the exact weight in the data table (already prepared) in your notebook. Use a cork ring to keep the flask upright as it rests on the balance pan (and elsewhere). Add 4-5 mL methanol and 0.5 mL conc. H2SO4 (ten drops) to the flask. Affix a water-jacketed condenser to the flask and clamp the assembly so the flask rests in the well of your (blue) heating mantle. Heat the contents with stirring to reflux for at least 90 minutes. [During the heating period your instructor may ask you to conduct the tasks for the first laboratory practical exam, or he might provide additional details on the work-up procedure.] {If the heating time has been less that 90 minutes, leave the assembly set up; the instructor will take care of the remaining steps.} Allow the mixture to cool to room temperature, then disassemble the apparatus and store your crude reaction mixture in your drawer (glass stopper, flask held upright in a beaker) until next lab period. Leave the condenser set up and the heating mantle out for the second group. 2nd period Transfer the contents of the flask to a small separatory funnel, along with 10 mL of satd. aq. sodium bicarbonate. Extract the mixture with 2 x 10 mL dichloromethane. Combine the lower (organic) layers and place these back in the empty separatory funnel. Wash the organic layer with 5 mL satd. aq. sodium bicarbonate. Drain the lower organic layer into a small (25- or 50-mL) Erlenmeyer flask and add ~1g of anhydrous sodium sulfate to dry the solution. After 5 minutes with the Na2SO4, if there is freely flowing Na2SO4 in the flask, decant the liquid into a small, pre-weighed round-bottom flask. (If the Na2SO4 is completely clumpy, add more, and wait another 5 minutes, then decant. Remove the solvent by rotary evaporation (instructor will demonstrate). Reweigh the solvent-free(?) product, then blow a gentle stream of air over the product and reweigh again. Repeat the blowing-and-reweighing process until the mass stops changing, and use this mass for calculating a percent yield. Obtain an FTIR and a refractive index for the product. The instructor will provide an authentic spectra NMR spectrum once the other physical characterizations have been completed. You must clean ALL your glassware except the flask containing the Na2SO4; that should stay open in your draw until next lab meeting. You may stop after any of these points: You’ve decanted the dried solution into the tared r.b. flask; • You’ve evaporated the CH2Cl2 on the rotovap (cork flask loosely for storage); • You’ve recorded the stable, unchanging mass for the pure product; • You’ve taken an IR for the pure product; • You’ve taken a refractive index for the pure product; • You’ve handed in the product.