Lab Report 2

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A Diels-Alder reaction with Anthracene and Maleic Anhydride Shannon Scott Section 602 Shanelle Suepaul 09/12/2022

Introduction : In this experiment the reaction that was performed was a Diels-Alder reaction. In order to do this reaction anthracene and maleic anhydride must mix to synthesize 9-10-dihydroanthracene-9,10- α , β -succinic anhydride. This reaction is performed in a concerted cycle addition that happens between dienes and dienophiles ( Hoare,2022). Important parts of this reaction are the dienes and dienophiles. In a dienophiles there needs to be at least one pi bond while in a dienes there has to be two adjacent pi bonds within the compound. in order for this reaction to take place the dienes has to be electron rich so it can donate it’s electrons and acts as the strong electron donating group. As for the dienophiles it is electron deficient so it will act as the strong electron withdrawing group. The dienophiles in the experiment was the maleic anhydride and the diene was the anthracene. In order for this reaction to happen there has to be some stereochemistry done. This is because this reaction is stereospecific. The diene must be s-cis in order for this reaction to occur. And dienophiles has to either be cis- or trans- for this reaction to occur ("11.3.7 The Diels-Alder Reaction", 2022). Materials:  Round bottom flask 10 mL  .6 g of anthracene  .3 g of maleic anhydride  6 mL of xylenes  ice  water  two 250 mL beakers  100 mL beaker  filter paper  condenser  thermometer  heat source  Büchner funnel  scale Procedure: Take a 10 mL round bottom flask and put in .6 g of Anthracene and .3 g of Maleic Anhydride into it. Record the mass and then add is 6 mL of xylenes. Set up reflux and the condenser and add calcium chloride. Heat the mixture for 30 minutes and measure the temperature. While that is going prepare to ice water baths using 250 mL beakers. Then take 10 mL of xylenes and place it into a beaker into the ice water. after 30 minutes of refluxing wait 15 minutes to cool the flask by placing it in the 2nd cup of ice water. Now collect the crystals and way the filter paper. Set up the vacuum filtration and wash solid product with xylene. Place a filter paper in the glass and stream air through the solid. Now weight the filter paper and calculate the percent yield record the mass and determine the melting point.

Date: Compound Mass (g) Anthracene 0.604 Maleic Anhydride 0.296 Crystal Mass (g) 9-10-dihydroanthracene- 9,10- α , β -succinic anhydride 0.871 Results/Calculations: Moles of Anthracene = 0.6 178.23 g = 0.3366 mol Moles of Maleic Anhydride = 0.39 98.06 g = 0.00306 mol Theoretical Yield= 0.00306 mol× 276.3 g mol = 0.845 g Percent Yield = Actual Theoretical × 100 = 0.871 g 0.845 g × 100 = 103%

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Figures: Analysis: In the diels-alder reaction the 9-10-dihydroanthracene-9,10- α , β -succinic anhydride was synthesized from anthracene and maleic anhydride. The percent yield of our final product was 103%. This percent yield was rather high which means more of our sample was recovered than what we anticipated. This could be due to the fact that instead of putting in 6 mL of xylenes we ended up playing in only 4 mL because the graduated cylinder the numbers were reversed so we thought we were putting in 6 ml but instead we only put in 4 mL. The unusually high percent yield could have been affected because of some human error while putting our product into the vacuum filtration apparatus with the filter paper. If we didn’t get all the product out of the round bottom flask then there will be impurities with our final numbers. as for the melting point of our final product we got a melting point of 208°C. according to our lab manual the melting point should’ve been around 260°C. Our number was off by 52°C. This could be due to some impurities within our experiment. melting point of our product could’ve been lower because there were small amounts of impurities within the final product. this could also be due to the fact we only put in 4 mL of xylenes Instead of 6ml. Post-lab: 1. With this reaction it is very useful to use to form carbon-carbon bonds as well as it is a highly regioselective reaction. Also, the mechanism is very easy to understand because it is concentrated. 2. Since this reaction is a concentrated cycle addition a polar solvent is not required. since electrons move simultaneously there is no need for the polar solvent to stabilize it.

Reference: 11.3.7 The Diels-Alder Reaction . Chemistry LibreTexts. (2022). Retrieved 18 September 2022, from https://chem.libretexts.org/Courses/Purdue/Purdue %3A_Chem_26605%3A_Organic_Chemistry_II_(Lipton)/ Chapter_11.__Addition_to_pi_Systems/11.3%3A_Concerted_Additions/ 11.3.7_The_Diels-Alder_Reaction . Hoare,A., Pandey,M. , Weldegirma, S. Organic Chemistry II Laboratory Manual ; University of South Florida: St. Petersburg, Florida,2022; pg 53-55