LAB AND 1,2,3,4,5 ON THE POST LAB!! THANK YOU SO MUCH!!
- Please Help I Will Rate I Need Answers To 1 2 3 4 On The Pre Lab And 1 2 3 4 5 On The Post Lab Thank You So Much 1 (155.07 KiB) Viewed 20 times
- Please Help I Will Rate I Need Answers To 1 2 3 4 On The Pre Lab And 1 2 3 4 5 On The Post Lab Thank You So Much 2 (63.92 KiB) Viewed 20 times
Synthesis of N,N-diethyl-m-toluamide (DEET) Instructor Demo Personal Protective Equipment Requirements Safety Glasses Lab Coat X X X Gloves Nitrile Gloves Heavy Fume Hood Bio Hood Instructor Always General Background: DEET, or N,N-diethy-m-toluamide, is the major ingredient in the mosquito repellent "OFF". It is currently believed that mosquitoes find their victims primarily by sensing the CO2 breathed out and the convection currents of warm, humid air produced by warm-blooded animals. Successful repellents seem to work by jamming the insect's moisture sensors. Not only must repellents possess this jamming ability, but they should be effective for several hours, be nontoxic and nonirritating to the skin, free of unpleasant odor, and harmless to clothing. The short, two-step synthesis of DEET involves the chlorination of a carboxylic acid converting it into a more reactive acid chloride, which in turn is converted into an amide by reaction with diethylamine. OH SOCI₂ m-toluic acid m-toluoyl chloride N,N-diethyl-m- toluamide Experimental Procedure: Assemble a reflux apparatus that will use a 100 mL round bottom flask, but do not connect the 100 mL round bottom flask to the apparatus yet. Be sure to place a magnetic stir bar in the 100 mL round bottom flask. Preparation of m-toluoyl chloride: Place 2.8g of m-toluic acid in the 100 mL RBF and attach it to the reflux apparatus. Once your assembly is complete, Your instructor will add 3.0 mL of thionyl chloride. Note: SOCI2 is an extremely corrosive and toxic. It reacts readily with moisture in the air or mucous membranes. Wear gloves if handling and work in hood. Wash with copious amounts of water if you come in contact with this reagent. ہو۔
Reflux the mixture until gas evolution ceases (approximately 40 minutes). Periodically test the vapor escaping from the top of the condenser with a piece of wetted litmus paper. (Think about the bi-products of this reaction. What do you expect to see on the litmus paper?) Preparation of N,N-diethyl m-toluamide: While waiting for the m-toluoyl chloride reflux, prepare a solution of 7.0 mL diethylamine in 20.0 mL of diethyl ether in a dry 125 mL Erlenmeyer flask, then stopper the flask immediately. Keep it stoppered until you transfer the solution to a separatory funnel. Once the reflux of m-toluoyl chloride is complete, stop the reflux and cool the round bottom flask to room temperature with a tap water bath and then add 25-ml of diethyl ether. Swirl to mix. Remove the condenser and heating equipment, but keep the stirrer. Slowly (dropwise at first) add the diethylamine/ether solution from the separatory funnel to the RBF containing the toluoy! chloride (NOTE: do not connect the separatory funnel to the RBF. In doing so, you would create a closed system. Please leave space between the funnel and RBF. See picture below.) Stir for 5 minutes once addition is complete. Q NO 8 tomo 2. YE + YE
NO YE YE 8 Pour the reaction mixture back into the separatory funnel and wash it successively (twice) with 20 mL portions of 10% NaOH then 20 mL 3.0M HCI. Transfer the washed ether layer (containing the desired product) to your 125 mL Erlenmeyer flask, add MgSO4, and allow to sit for 10 minutes. Then gravity filter the solution into your cleaned and acetone dried PRE-WEIGHED 100 mL round bottom flask, then rotary evaporate the ether to obtain the final mass of DEET as an oil. Analyze the crude oil by IR and NMR (CDC13). Dispose of your DEET in appropriately labeled bottle. Lab Follow-up Questions: 1. You extracted with 10% NaOH and 3.0M HCI. Was it necessary to extract with 3.0M HCI? Explain why or why not. 2. Calculate the yield for this reaction (show your work). What could you have done different to increase the yield for this reaction? This experimentally... human error and transfer loss are not acceptable answers. 3. What other methods could you use to monitor this reaction? Be specific on what monitoring technique you would use, and exactly what you are monitoring with your selected technique. 4. Draw the "curly arrow" mechanism for the reactions in this lab. Identify the pka's for all the nucleophiles and leaving groups in your mechanism. 5. How pure was your final compound? Identify functional peaks in your IR. You will not receive full credit for this question unless your IR's are attached and the peaks identified! 8
tab cap shit fn Analyst Date Student User Thursday, February 03, 2022 2:56 PM 3500 3000 2500 cm-1 23 2022_015 Sample 015 By Lab Date Thursday, February 03 2022 100- 95 90- 85 80- 75- 70- 65 60- 55 50- 45 40- 35 347 4000 2000 1500 PerkinElmer Spectrum Version 10.5.1 Thursday, February 03, 2022 2.56 PM 1000 650 Page 1