You think you have isolated aspirin (acetylsalicylic acid) in the lab. It melts at 75-77oC. Since you don’t totally trust your own laboratory techniques, you want to prove to yourself that you have aspirin. Using IR spectroscopy and melting-point techniques, explain how you can prove that you actually have aspirin (assume the stockroom is able to supply you with any compound you need). Term
IR: Should see -OH band at 3000 - C=O at 1735 (ester) - sp2 C-H at 2980 - C=C at 1600 Then: Compare to known standards of IR
MP: 1) compare it to lit. value 2) mix the standard and unknown and take mp - should be the same mp (no depressions/broadening)
1. Emulsions tend to happen more often with ether/water extractions than CH2Cl2/water extractions. 2. In a distillation, you want to always boil the pot to dryness to ensure you have obtained all the liquid you can as distillate. 3. On a condenser, water always goes in at the high point and out at the low point. 4. On a steam bath, the live steam connection should be connected to the bottom (lower) connector of the steam bath. 5. One way to help clear an emulsion is to add brine solution to the mixture.
1. T 2. F 3. F 4. F 5. T
1. A flash point listed in degrees Celsius for a compound is the temperature above which it can form an ignitable mixture with air. 2. In a recrystallization where you may have added too much solvent to have crystals form, the best solution is to first boil off half of the liquid.
You have added too much drying agent to your organic solution and completely covered the organic solution. Briefly explain how you can salvage the solution.
Add a small portion of organic solvent to mixture. Transfer the liquid to another flask. Rinse drying agent with more organic solvent 1. combine with 1st solution 2. filter it, wash the drying agent on filter paper with solvent, combine with 1st solution