Practice important
Deactivated Aromatic Rings
MCQ questions and answers.
Page 1
of
1
|
10
MCQ Questions
1. Which aromatic compound generally does not undergo Friedel-Crafts acylation because its ring is strongly deactivated?
A.
Benzene
B.
Nitrobenzene
C.
Toluene
D.
Ethylbenzene
Correct Answer:
Nitrobenzene
Explanation:
The nitro group strongly withdraws electron density from the benzene ring, making nitrobenzene too deactivated for Friedel-Crafts acylation.
2. Why does nitrobenzene resist Friedel-Crafts acylation?
A.
The nitro group activates the ring strongly
B.
The nitro group withdraws electron density from the ring
C.
Nitrobenzene has no benzene ring
D.
The nitro group changes into an alkyl group
Correct Answer:
The nitro group withdraws electron density from the ring
Explanation:
The electron-withdrawing nitro group decreases the electron density of the aromatic ring, so it cannot readily attack the acylium ion.
3. Which group makes an aromatic ring unsuitable for Friedel-Crafts acylation because it strongly deactivates the ring?
A.
Methyl group
B.
Ethyl group
C.
Nitro group
D.
Methoxy group
Correct Answer:
Nitro group
Explanation:
The nitro group is strongly electron withdrawing and greatly reduces the reactivity of the aromatic ring toward Friedel-Crafts acylation.
4. Friedel-Crafts acylation generally does not occur readily with which compound?
A.
Benzene
B.
Toluene
C.
Ethylbenzene
D.
Benzoic acid
Correct Answer:
Benzoic acid
Explanation:
The carboxyl group in benzoic acid withdraws electron density from the ring, strongly deactivating it toward Friedel-Crafts acylation.
5. Which compound contains an aromatic ring deactivated by a carboxyl group?
A.
Benzoic acid
B.
Toluene
C.
Anisole
D.
Ethylbenzene
Correct Answer:
Benzoic acid
Explanation:
Benzoic acid has a carboxyl group attached directly to the benzene ring. This group withdraws electron density and deactivates the ring.
6. Which aromatic compound is least likely to undergo Friedel-Crafts acylation because of a strongly electron-withdrawing cyano group?
A.
Benzonitrile
B.
Toluene
C.
Ethylbenzene
D.
Anisole
Correct Answer:
Benzonitrile
Explanation:
The cyano group in benzonitrile withdraws electron density from the aromatic ring, making the ring strongly deactivated toward Friedel-Crafts acylation.
7. Which group directly deactivates an aromatic ring toward Friedel-Crafts acylation?
A.
–CH3
B.
–C2H5
C.
–NO2
D.
–OCH3
Correct Answer:
–NO2
Explanation:
The –NO2 group is strongly electron withdrawing, so it lowers the electron density of the aromatic ring and prevents easy Friedel-Crafts acylation.
8. A benzene ring bearing which group is strongly deactivated toward Friedel-Crafts acylation?
A.
–COOH
B.
–CH3
C.
–C2H5
D.
–OCH3
Correct Answer:
–COOH
Explanation:
The –COOH group withdraws electron density from the ring and therefore strongly deactivates it toward electrophilic substitution such as Friedel-Crafts acylation.
9. Which statement about nitrobenzene in Friedel-Crafts acylation is correct?
A.
It reacts faster than benzene
B.
It generally does not undergo the reaction readily
C.
It acts as an activating alkylbenzene
D.
It has no effect on the reaction rate
Correct Answer:
It generally does not undergo the reaction readily
Explanation:
Nitrobenzene is strongly deactivated by the electron-withdrawing nitro group, so Friedel-Crafts acylation is generally difficult or does not occur.
10. Which aromatic compound is deactivated because its ring bears a formyl group, –CHO?
A.
Benzaldehyde
B.
Toluene
C.
Ethylbenzene
D.
Anisole
Correct Answer:
Benzaldehyde
Explanation:
Benzaldehyde contains a formyl group attached to the ring. The –CHO group withdraws electron density and makes the ring unsuitable for easy Friedel-Crafts acylation.
Short Questions and Answers
Practice short questions and answers related to
Deactivated Aromatic Rings
.
Short questions are currently unavailable for this page.