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16 Pre Lab - lab work
Organic Chemistry Lab II (CHEM201401)
Boston College
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PreLab 16
Caution: Hazzard of 1,6-diaminohexane. Contact and vapor hazard for sebacoyl chloride in hexane. No chemicals from this experiment should be poured down the sink since this will clog the drains!
Part 1. Nylon by Interfacial Polymerization
Add 10 mL of 1,6-diaminohexane into a 50 mL beaker. Get 10 mL of 0 M sebacoyl chloride in hexane and transfer the solution slowly by pouring it down the interior wall. Let solution stand undisturbed for 1 minute. A white film of Nylon polymer should form at liquid interface.
Using forceps, reach into center and grasp the Nylon film at interface. Slowly, pull up the polymer vertically while wrapping the top of the strand around center of large test tube (25x100mm). Rotate it and continue drawing it out from center of the beaker at steady rate. If nylon snaps, a fresh strand can be made with forceps but should be possible to continue drawing an unbroken Nylon strand until the bulk of the reaction mixture has been consumed.
Rinse the excess solvent from surface of spool by rotating the test tube under stream of tap water. Slide the nylon from the test tube but keep the loop intact. This can be done by inserting a metal spatula between the two. Record physical appearance and texture of nylon and note the tensile strength of the wet nylon by stretching the loop until it snaps. Lay it on a paper towel to drain by blotting it between two towels. Remove a small amount of polymer to test its solubility in toluene, acetone, and methanol. Record these observations. Weigh the polymer and weight next week.
To clean the test tube and beaker, scrape with metal spatula. Do not wash.
Part 2. Condensation Polymerization of Phenol and Formaldehyde: Bakelite Caution: Wear gloves when handling phenol; it is a toxic substance and can cause serious burns. Wear gloves when handling formaldehyde; it is a carcinogen.
3 mL of liquefied phenol and 10 mL of 37% (by weight) aqueous formaldehyde solution in a 25 mL round-bottom flask. 1 mL of concentrated aqueous ammonia to the flask. Swirl the flask to mix. Reflux the reaction mixture using a thermowell (make sure the solution reaches boiling point). Watch the solution as you heat it and record observations and when it becomes cloudy. Once it turns cloudy, heat for additional 5 minutes. In total 15-20 minutes.
Pour the warm reaction mixture into the test tube provided by your TA. Immediately wash the round-bottom flask with acetone. The solution in the test tube will consist mostly of a cloudy, upper layer and a smaller, darker, lower layer. Remove the cloudy upper layer using a Pasteur pipet and put in the appropriate Byproducts jar.
PreLab 16
Obtain a steam bath and warm the test tube. While heating, add acetic acid dropwise to the thick mixture. Obtain a wooden stick and stir contents during addition. Stop addition once the solution is clear (1-2 mL). Avoid too much acetic acid.
Obtain a hot plate and temperature probe and heat a beaker of water to 60-65. In this hot water bath, heat the test tube for 30 minutes. Place the wooden stick in the center of the polymer in the test tube, and label the test tube clearly with your name, lab period and TA's name. Give the test tube to your TA, and it will be placed in an 80-85° oven. The polymer will be removed from the oven the next morning and returned in lab next week. Next week: break up some of the polymer into small pieces and test its solubility in toluene, acetone and methanol. Record next week.
Part 3: Synthesis of a Co-polymer of Styrene and Maleic Anhydride Caution: Styrene: use only in the fume hood. Avoid contact and keep it away from flames. Maleic anhydride is corrosive and toxic. Benzoyl peroxide is a flammable solid that may explode on heating or impact. Use only a small amount. Do not leave benzoyl peroxide in contact with paper, cloth or wood and clean all spills immediately with water.
In dry 100 mL round bottom flask, add 2 mL (4 g) of styrene and 1 g of maleic anhydride, 30 mL of toluene and 0 g of benzoyl peroxide (dispense using a plastic spoon). Swirl the flask and most of the solid material has dissolved (may still be somewhat cloudy). Add a boiling chip. Reflux the reaction mixture, using a thermowell, for 15 minutes. Record when a precipitate forms.
Let mixture cool to room temperature. Add 10 mL of methanol and stir with a glass rod. Collect the product by vacuum filtration. Wash with methanol. Remove the boiling chip. Let it to dry. Place the filtrate in the appropriate Byproducts jar.
Record and test the solubility of the small piece of polymer in toluene, acetone and methanol. Spread the polymer on a piece of filter paper or a watchglass and in your drawer. Weigh the dry polymer next week.
16 Pre Lab - lab work
Course: Organic Chemistry Lab II (CHEM201401)
University: Boston College
