Experiment 4 Lab Report PDF

Preview

Summary

Download Experiment 4 Lab Report PDF

Description

Diels-Alder Cycloaddition Purpose: The purpose of this experiment is to react anthracene with maleic anhydride in a reflux solution in order to perform a Diels-alder cycloaddition reaction. Reaction and Physical Properties Table

Reagents and Solvents anthracene Maleic anhydride xylenes Ethyl acetate

MW g/mol 178.83 98.06

amount

mmol 0.447 0.408

Boiling point (oC) 340 202

Melting point (oC) 216 52.8

80mg 40mg

106.2 88.11

1ml 1ml

-

~140 77.1

-83.6

Safety Maleic Anhydride (Irritant) Risk statements: Irritating to skin, corrosive. Orally toxic. Safety Statements: Wear all proper protective gear. Use in well ventilated area. Wash any exposed skin with water, thoroughly rinse. Ethyl Acetate (Flammable) Risk statements: Irritating to skin, corrosive. Orally toxic. Flammable Safety Statements: Wear all proper protective gear. Use in well ventilated area. Wash any exposed skin with water, thoroughly rinse. Do not use near an open flame. Anthracene (Irritant) Risk statements: Irritating to skin, corrosive. Orally toxic. Safety Statements: Wear all proper protective gear. Use in well ventilated area. Wash any exposed skin with water, thoroughly rinse. Xylenes (Flammable) Risk statements: Irritating to skin, corrosive. Orally toxic. Flammable Safety Statements: Wear all proper protective gear. Use in well ventilated area. Wash any exposed skin with water, thoroughly rinse. Do not use near an open flame. Procedures: 1. Add 80 mg of anthracene and 40mg maleic anhydride to 3ml conical vial. Add roughly 1 ml xylenes and a boiling chip 2. Attach air condenser and heat on hot plate in hood. Reaction should be visibly boiling and xylene running back into container. Start with 350oC

3. Reflux for 30 minutes (Start time when reaction starts refluxing, not when set on hotplate) Look for color changes 4. Remove from heat and allow to cool to room temperature. Cool 10 minutes in ice bath to maximize crystallization of product. 5. Collect using suction filtration through a Hirsch funnel and wash twice with cold ethyl acetate (2x~0.5mL) pull air through crystals to help evaporate solvent.

6. Get mass of isolated product (remove boiling chips before weighing) 7. Get melting point of product. Needs to be between 261-262oC. Digimelt will not heat about 260oC so if product melts below, isolation has not occurred and impure product. 8. Obtain IR spectrum using ATR. 9. Obtain 1H NMR spectrum of product and save data file using section number and intial of everyone in the group. Make sure to use minimum of 20mg product to 0.6mL of CDCl3. Do not dispose of NMR tube after use. Data/Observations Although I did complete the experiment in person, I will be using the provided data due to my product not being accurately weighed. Initial amount anthracene: 0.0857g Initial amount Maleic acid: 0.0428 g

Initially placed on to the hotplate, mixture was a yellowish mixture. Reflux process began. Total time on hotplate was 40 minutes due to the time needed to allow mixture to begin boiling. Allowed to cool after reflux for 10 minutes and filtered. Mishap with filter process meant a great amount of product was lost in the process, had to use provided data. Product: 0.0216g

Calculations and Results !.!#$%& Anthracene Mols:

= 4.8𝑥10-4 mols

Maleic Acid mols:

= 4.4𝑥10-4 mols

'%#.#()&/+,!.!./#& 0#.!1&/+,-

4.8x10-4 mols anthracene + 4.4x10-4 mols maleic acid =9.2x10-4 mols !.!/'1& Product: = 7.8𝑥10-5 mols ! /%1.#0"#$23,4567 %.#89$

Percent yield:

0./89.

=0.0848 x 100%=8.48%

Conclusions/Discussion In this experiment, the goal was to perform a diels-alder cycloaddition reaction. This reaction uses an electron rich diene and a electron poor dienophile to form a new 6 membered ring. This new product is more stable due to the nature of the reaction. When viewing the IR spectrum, a peak is seen near the 3000cm-1 and although it is a small peak, it still hint at steric strain on the molecule. Another peak was found at 1780cm-1 which shows the C=O bond. An H1 NMR spectrum was also obtained with the product. A peak at 3.5 with 2 H’s due to the integral. A second peak at 5 contained 2 H’s and a third peak at 7.5 contained 8 H’s. The third peak shows a great amount of splitting and it’s location suggests that is is in the proximity of the double bonded oxygen. These properties presented in the product graphs show that the product was properly isolated. If this experiment was redone, a significant amount of care would be used to ensure no mishaps with the prodct during the isolation process, in order to achieve an accurate weight. Post Lab Questions

1. Where do you find peaks for Csp3-H bonds in IR spectra? How can this help you characterize your reaction product? Peaks would appear at the 3000cm-1 region of the spectrum. Normal C-H would occur at less than 3000cm-1 but due to the steric strain on the molecule, the peak absorption occurs at 3000cm1 instead. This peak being present helps to determine if the product reacted and was isolated or not. 2. How does the anhydride group of maleic anhydride increase the reactivity of the C=C of the compound as a dienophile? A dienophile is electron deficient so the presence of a electron withdrawing group will increase the reactivity that are attached to the sp2 carbons. 3. Suggest a reason why maleic anhydride reacts with anthracene at the 9,10-position (shown in the reaction above) rather than other ring locations? (Hint: See Chapter 15, Section 6 of Smith, Janice; Organic Chemistry). Anthracene is an aromatic compound and the 9,10 location is ideal because the center ring only has 4 electrons instead of the normal 6 of benzene. The 9,10 position reacts and gives two complete benzene rings, making the product more stable. 4. What is the product of the following reaction?

Product: O

H H

O...