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Prelab Organic Chem 9
Organic Chemistry Lab II (CHEM201401)
Boston College
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Prelab Orgo 9
Hazards 1. Pyridine is an irritating and toxic liquid. Use only in the fume hood and avoid contact with skin. 2. Benzoyl chloride is a lachrymator (tear gas) and is moisture sensitive. Work with this liquid in a fume hood! 3. Acetic anhydride is corrosive. Avoid contact with skin. 4. Phosphoric acid is corrosive. Avoid skin contact 5. Cholesteryl benzoate is irritant, keep away from ayes, skin, and mouth 6. Methanol is flammable and toxic, keep away from open flames and skin. Wash immediately if skin contact occurs 7. Ethyl acetate is highly flammable, keep away from open flame and work under fume hood 8. Acetic anhydride is flammable, irritant, and corrosive. Keep away from open flam and wash immediately if skin contact, work with under fume hood 9. Handle hot plate and boiling water carefully to avoid burns
Synthesis 1. Weigh 1 of cholesterol and add to 50mL Erlenmeyer flask. Dissolve cholesterol by adding 3mL of pyridine and swirling 2. Use the syringe attached to Pasteur pipet and measure 0 of benzoyl chloride and add it to the flask. Heat in steam bath for 10 minutes 3. Swirl flask in a beaker of cold water to cool down. Dilute the mixture with 15mL of ethanol and collect the solid by vacuum filtration with the Buchner funnel and 125mL side-arm flask. Rinse out flask using methanol 4. Place cholesterol benzoate on a steam bath with 20mL of ethyl acetate until it has dissolved to recrystallize it. Gravity filtrate solution If some solid material has not dissolved. Place a small amount of ethyl acetate on receiving flask and place it on a steam bath. Line a stemless funnel with fluted filter paper and allow vapors to warm the funnel. 5. Allow the ethyl acetate solution to cool to room temperature, then put on ice. Use a Buchner funnel to perform vacuum filtration and collect the crystals while washing the with cold ethyl acetate. 6. Weigh the dried crystals. Mix equal amount of the recrystallized product and cholesterol. Obtain the melting points of the purified product and the mixture
Observing the liquid 1. Place 0 of cholesteryl benzoate on a glass microscope slide and rest this end on a hot plate on high setting. Solid will melt, turning cloudy and then clear. 2. After clear liquid appears, use test tube holder to grasp the end of the slide that contains no material and remove from hot plate. Shine a lamp where the sample is present and record observations
Synthesis and purification
- Heat a 400mL beaker with 150mL of water to boiling point. Add 2g of salicylic acid to a 125mL Erlenmeyer flask and dispense 5mL of acetic anhydride into this same flask.
- Add 5 drops of 85% phosphoric acid swirl flask to mix and add to boiling water bath for about 8 minutes. Add 2mL of deionized water to the flask, which will react with any remaining unreacted acetic anhydride
- When reaction has subsided, add 40mL of water to the flask and allow the contents to cool at room temperature for 10 minutes, then place flask in ice. Use a glass rod to stir contents during cooling. Collect the solid by vacuum filtration and wash crystals with ice- cold water. Set aside a small portion of crude acetylsalicylic acid
- Transfer the acetylsalicylic acid into a 255mL flask and add 6mL of 95% ethanol tp recyrstallize. Heat flask on hot plate until aspirin dissolved and remove as soon as solid dissolved. Add water to solution by 5mL portions and swirl after adding until a total of 25mL has been added
- Place flask in ice bath for 10 minutes and collect the purified aspirin by vacuum filtration. Wash crystals with ice-cold water. Leave vacuum for a few minutes, place crystals in oven to dry them. Obtain melting points of dry product
Solubility tests
- Test solubility of purified acetylsalicylic acid in toluene and hot water; observe what happens when aqueous solution is cooled and when rubbed against the tube with stirring rod
- Test solubility of purified product in 1 sodium hydroxide and then add an equal amount of 1 hydrochloric acid
- Rest the solubility of an aspirin table in toluene and hot water and compare results with product. Obtain melting point of the table. Observe what happens to commercial aspirin in melting capillary and compare with observations of your product
Phenol tests 1. Prepare 5 clean, small test tube and place spatula tip amount of the following: a. Test tube 1: salicylic acid b. Test tube 2: your crude product c. Test tubes 3 and 4: your purified product d. Test tube 5: empty (control) 2. Add 5-10 drops of water to test tub es 1-3 and 5 3. Add 5-10 drops of 0 HCL to test tube 4 and heat in beaker of boiling water for 5 minutes 4. Add 1-2 drops of 1% ferric chloride to each of the five test tubes and record observations
Prelab Organic Chem 9
Course: Organic Chemistry Lab II (CHEM201401)
University: Boston College
