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14 Pre Lab - lab work
Organic Chemistry Lab II (CHEM201401)
Boston College
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Cautions: Aluminum chloride is hygroscopic so keep it capped. Acid anhydrides are corrosive so avoid breathing vapors and keep away from water. CH2Cl2 is suspected carcinogen so wear gloves.
Work with a partner 1. Small magnetic stirring bar and put it into a 40 mL vial. Add 0 g of aluminum chloride to the vial. 5 mL of toluene in graduated cylinder. 0 mL of unknown acid anhydride with a syringe and pipet assembly and add this into the toluene. Mix using pipet in the graduated cylinder. 2. Put ice and water into a beaker and place it on a hot plate. Use a clamp to clamp the vial containing aluminum chloride into the ice bath and turn on the stirrer. Add toluene and anhydride mixture into the vial slowly with pipet (requires 2 minutes of addition). Transfer the mixture from the vial into a microwave vessel by using a pipet. If there are any solids in the vial, don’t transfer into the microwave vessel. To get the magnetic stirring bar into the vessel, use a spatula. 3. Plug the vessel at the top by using the vent plug. Cover using a cap and twist until the cap is finger tight. With TA supervision and using special tool, turn cap until it clicks into place. Use a kimwipe to wipe off the outside of vessel. Write names on the vessel using a marker. If there are any solids on the side, tilt the vessel so solid dissolved in liquid. TA will place vessel in carousel. Record number of position. 4. TA will place into MARS reactor. Conditions: 200 W, 110ºC, 5 minutes (ramp), 12 mins (hold). Once heating step is finished, the mixture will be cooled in the instrument. When temp reaches 50º, TA will distribute vessels. In fume hood, use special tool to slowly loosen the cap while pointing vessel toward the back of the hood. DO NOT LOOSEN RAPIDLY OR GASSES WILL ESCAPE AND POINT TOWARD BACK. 5. Record mass of 25 mL side-arm filter flask 6. 4 mL of deionized water to microwave vessel. Place vent plug on top and cap vessel (finger tight) and shake vigorously. Transfer contents of vessel to separatory funnel and carefully remove stirring bar. Dispense stirring bar in beaker jar at trash hood. Rinse vessel with additional 10 mL of water and then with 3 mL of diethyl ether. Add rinses to sep funnel. 7. 5 mL of diethyl ether into sep funnel and mix layers very gently to avoid emulsions. Drain two layers into separate flasks labeled with organic and aqueous. Return aqueous layer into sep funnel and continue extracting with two more 8 mL portions of diethyl ether. Return the combined organic layers to sep funnel and wash with three 8 mL portions of saturated sodium bicarbonate solution, venting frequently. Wash the organic layer with two 10 mL portions of saturated sodium chloride. If the solution is still cloudy after second wash, repeat a third time. Dry organic layer over anhydrous magnesium sulfate, then filter it into 40 mL vial. 8. Evaporate solvent in centrifan until 5 mL of liquid remains. Transfer vial solution into tared side arm flask. Use small amounts of ether to rinse the vial and add this to filter flask. Place #5 stopper in the mouth of the flask. Attach side arm to vacuum. Slowly
open valve. Use steam bath to evaporate the remaining solvent (mostly toluene) under vacuum. Turn off vacuum when a dark colored oil remains. Record mass of the product. 9. IR SPECTRA: Obtain IR of unknown acid and product as neat liquids. Prepare samples by placing two drops of the compound on a salt plate and placing another salt plate on top of liquid. After obtaining spectrum, clean salt plates with CH2Cl. And dry with kimwipe. Put waste into byproducts. 10. NMR SPECTRA: obtain NMR. Place two drops of compound into small vial. Use pipet and syringe assembly provided, add 0 mL of CDCl3 solvent to vial. Transfer solution into NMR tube using Pasteur pipet. Make sure height of liquid in tube is 5 cm (compare to marked nmr tube). If too low, add some drops of CDCl3 until reaches height. Attach cap to NMR tube. TA assist in obtaining spectrum. Empty contents of NMR tube into Chloroform-d Byproducs jar and place tube in beaker labeled dirty NMR tubes.
14 Pre Lab - lab work
Course: Organic Chemistry Lab II (CHEM201401)
University: Boston College
