Q: Which IR absorption would you expect to disappear in the product after a successful Diels-Alder reaction between anthracene and maleic anhydride?

The C=C stretch of anthracene at $$\sim 1600\ \text{cm}^{-1}$$

Question 1

Which of the following statements best describes the Diels-Alder reaction?

Accepted Answer

It is a [4+2] cycloaddition reaction between a conjugated diene and a dienophile, forming a six-membered ring.

Question 2

Which of the following dienes will NOT react in a Diels-Alder reaction?

Accepted Answer

A diene locked in the s-trans conformation

Question 3

What is the main reason maleic anhydride is an excellent dienophile in the Diels-Alder reaction?

Accepted Answer

It contains two strong electron-withdrawing groups that activate the double bond.

Question 4

Which of the following best explains the endo rule in Diels-Alder reactions?

Accepted Answer

The electron-withdrawing group on the dienophile prefers to be oriented toward the newly forming π system (endo position) due to secondary orbital overlap.

Question 5

Which IR absorption would you expect to disappear in the product after a successful Diels-Alder reaction between anthracene and maleic anhydride?

Accepted Answer

The C=C stretch of anthracene at $$\sim 1600\ 	ext{cm}^{-1}$$

Question 6

Why is xylene used as the solvent in the Diels-Alder reaction between anthracene and maleic anhydride?

Accepted Answer

It has a high boiling point and low freezing point, aiding both the reaction and crystallization of the product.

Question 7

Which of the following best describes the stereochemistry of the Diels-Alder reaction?

Accepted Answer

The reaction is stereospecific and the configuration of the dienophile is retained in the product.

Question 8

Which of the following is a conjugated diene?

Accepted Answer

$$\mathrm{CH_2$=CH-CH=CH_2$}$$

Question 9

A student performs a Diels-Alder reaction and obtains a melting point significantly lower than the literature value. What is the most likely explanation?

Accepted Answer

The product is impure due to incomplete removal of solvent or reactants.

Question 10

Which of the following safety practices is NOT recommended during the Diels-Alder experiment?

Accepted Answer

Using spill pads for hot objects to avoid burns.

Question 11

Which of the following best describes the role of electron-donating and electron-withdrawing groups in the Diels-Alder reaction?

Accepted Answer

Electron-donating groups on the diene and electron-withdrawing groups on the dienophile increase the reaction rate.

Question 12

Which of the following is a cumulated diene?

Accepted Answer

$$\mathrm{CH_2$=C=CH_2$}$$

Question 13

A student accidentally uses a diene locked in the s-trans conformation for a Diels-Alder reaction. What is the expected outcome?

Accepted Answer

No reaction will occur because the s-cis conformation is required.

Question 14

Which of the following best explains why anthracene can act as a diene in the Diels-Alder reaction?

Accepted Answer

The central ring of anthracene is less aromatic and can participate as a diene, leaving two aromatic rings in the product.

Question 15

Which of the following is the correct curved arrow mechanism for the Diels-Alder reaction?

Accepted Answer

A concerted movement of three pairs of π electrons forms two new σ bonds and one new π bond.

Question 16

Which of the following is a key safety concern when handling maleic anhydride in the lab?

Accepted Answer

It is toxic and corrosive, requiring use of gloves and fume hood.

Question 17

Which of the following best describes the product of the Diels-Alder reaction between anthracene and maleic anhydride?

Accepted Answer

A bridged polycyclic aromatic compound with two aromatic rings and a succinic anhydride moiety.

Diels-Alder Reaction: Synthesis, Mechanism, and Analysis

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