Quiz 3: Diels-Alder Reaction of Furan & Maleic Anhydride (w/THF solvent)

Question 1

How will you determine the stereoisomer formed predominantly in the Diels Alder reaction of maleic anhydride and furan?

A. boiling point of product via distillation
B. proton shifts (ppm) of 1H NMR will be analyzed
C. integration from 13C NMR will be analyzed
D. coupling constant J will be measured for protons in 1H NMR

Answer 1

D

Question 2

How many signals are expected for the product in the 13C NMR spectrum? (see picture for Quiz 3)

A. 2
B. 3
C. 4
D. 5
E. 6

Answer 2

C

Question 3

How many signals are expected for the Diels-Alder product in the 1H NMR spectrum? (see picture for Quiz 3)

A. 2
B. 3
C. 4
D. 5
E. 6

Answer 3

B

Question 4

What are the reactants in this Diels-Alder reaction that yields the following product?

*Se Question 4 from Quiz 3

A. A + C
B. A + B

Answer 4

A

Question 5

In the 1H NMR spectrum, you notice signals at 1.85 ppm and 3.76 ppm. This signal is too large for the product. What is the source of these mysterious signals?

A. excess maleic anhydride
B. THF
C. furan
D. water

Answer 5

B

Question 6

What is the dienophile in the Diels-Alder reaction you will be performing this week?

A. furan
B. THF
C. maleic anhydride
D. product

Answer 6

C

Question 7

What is the expected splitting pattern for Hc in the 1H NMR spectrum? (seen on right)

*See Question 7 from Quiz 3

A. doublet
B. singlet
C. doublet of doublet
D. triplet

Answer 7

A

Question 8

What proton in the molecule above is most upfield in the 1H NMR spectrum? (seen on right)

*See Question 8 from Quiz 3

A. Ha
B. Hb
C. Hc
D. hard to determine

Answer 8

C

Question 9

Which of the following is true about the Diels-Alder reaction we will be performing in lab?

I. 2 σ bonds and 1 π bond are formed
II. concerted reaction
III. diene will mostly react in the s-trans conformation
IV. if the electron-donating group on dienophile, it will increase the reaction rate
V. stereochemistry of dienophile is retained in the product

A. only I
B. only II
C. only III
D. I, II, V
E. II, IV

Answer 9

D

Question 10

If the product is impure, you must recrystallize using a mixed solvent system using ethanol/water. What does this mixed solvent system mean?

A. Heat sample in minimal hot ethanol and add drops of hot/cold water until the cloud point is reached then allow solution to cool
B. Add ethanol until dissolved
C. Add water until dissolved

Answer 10

A

Question 11

After obtaining product for the Diels-Alder reaction, you rinse your crystals with cold THF. Why does the solvent need to be cold?

Answer 11

to minimize the product from solubilizing in THF