Diels-Alder Post Lab PDF

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Results and Discussion Sections for Diels-Alder Lab Report...

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Diels-Alder - [4+2] Pericyclic Reaction Results

Initial Weight of Anthracene

659 mg

Initial Weight of Maleic Anhydride

350 mg

Volume of Xylene Used for Reflux

6 mL

Volume of Xylene Used for Rinsing Crude Product

2 mL

Final Weight of Purified Product

0.893 g

Calculations Limiting Reagent Calculation 0.659 g anthracene 1 mol anthracene178.23 g anthracene1 mol diels alder adduct1 mol anthracene276.29 g diels alder adduct1 mol diels alder adduct= 1.021 g adduct 0.35 g maleic anhydride 1 mol maleic anhydride98.06 maleic anhydride1 mol diels alder adduct1 mol maleic anhydride276.29 diels alder adduct1 mol diels alder adduct=0.986 g adduct Limiting Reagent = maleic anhydride

Theoretical Yield Calculation Theoretical Yield = mol limiting reagent molar mass of adduct 0.35 g maleic anhydride 1 mol maleic anhydride 98.06 g maleic anhydride= 0.0036 mol maleic anhydride Theoretical Yield = 0.0036 mol maleic anhydride276.29 g adduct = 0.986 g adduct

Percent Yield Calculation Percent Yield = actual yieldtheoretical yield Percent Yield = 0.893g0.986 g 100=90.57%

Discussion The purpose of this experiment was to carry out a Diels-Alder reaction in the form of a reaction of anthracene with maleic anhydride. The experiment began with 659 mg anthracene and 350 mg of maleic anhydride in a round bottom flask. Anthracene was observed to be a grey sand-like solid while maleic anhydride was observed to be a white flaky solid. These starting materials were dissolved using approximately 6 mL of xylene, and the resulting mixture was refluxed. The mixture within the reflux apparatus was noted to be a deep amber liquid which proceeded to lose some of its yellow color throughout the reflux process. Once the reflux was complete, the mixture was cooled to room temperature. As the mixture cooled, crystals were already observed to be forming in the flask. The mixture was further cooled in an ice bath for approximately 10 minutes to induce recrystallization for the recovery of the final product. This product, fine, shimmery, off-white granules, was dried and collected via suction filtration during which, the crystals and flask were rinsed with an additional 2 mL of xylene. The recorded weight of the final product was 0.893 g. The limiting reagent was determined to be maleic anhydride. Using this, the theoretical yield was calculated to be 0.986 g 9,10-dihydroanthracene-9,10 -endo-α,ꞵsuccinic anhydride. From this value, the percent yield was calculated to be 90.57%. This percent recovery indicates a very successful experimental reaction in which little product was lost throughout the procedure. The crystal product collected was then used to record an IR spectra for comparison to known IR spectra for 9,10-dihydroanthracene-9,10-endo-α,ꞵ-succinic anhydride. On the IR spectrum of maleic anhydride, peaks at 1526 cm-1 and 1715 cm-1 supports the pentane ring as well as the carbon-oxygen double bonds attached to the ring that are known to be part of this compound’s structure while the peak at 3080 cm-1 supports the known carboncarbon double bond that makes up a portion of the ring. On the IR spectrum of anthracene, the peaks between 1526 cm-1 and 1715 cm-1, as well as the aromatic teeth located at 3048 cm-1 and 3093 cm-1 support the three aromatic rings known to make up this compound. On the DielsAlder adduct IR spectrum, peaks at 3050 cm-1 represent aromatic carbon- hydrogen bonds and the peak at 2980 cm-1 indicates the presence of alkane carbon-hydrogen bonds. The product spectrum also exhibits peaks at 1860 cm-1 and 1780 cm-1 , which indicates the presence of carbonyl groups from the maleic anhydride. The stretches located at 2127 cm-1 indicating overtones and at 1460 cm-1 and 1210 cm-1 indicating ring absorptions suggest the presence of aromaticity in the expected product....