Friedel–Crafts reactions and directive influence of substituents - One Line Questions

1. Which of the following is an example of a meta-directing group in electrophilic aromatic substitution? — -CHO
2. Which group directs incoming electrophiles predominantly to the meta position and deactivates the ring? — -COOH
3. Which of the following is an example of an ortho, para-directing group in electrophilic aromatic substitution? — -OH
4. Which of the following is a strong activating group and an ortho, para-director? — -OH
5. Which of the following substituents is a weak deactivator and an ortho, para-director? — -Cl
6. Which of the following substituents is least activating for electrophilic aromatic substitution? — -F
7. In electrophilic substitution of nitrobenzene, the incoming electrophile is directed to the meta position because the nitro group: — Deactivates the ortho and para positions more than the meta position
8. The relative rates of electrophilic substitution of monosubstituted benzenes follow the order: — Activating > Halogens > Deactivating
9. Which of the following is NOT a typical Lewis acid catalyst for Friedel-Crafts reactions? — H₂O
10. In Friedel-Crafts acylation, what is the electrophile generated? — An acylium ion
11. The reaction of benzene with fuming sulfuric acid (H₂SO₄ + SO₃) leads to: — Benzenesulfonic acid
12. Friedel-Crafts alkylation is generally not suitable for the alkylation of which type of aromatic compound? — Aniline
13. Which of the following reactions is an example of Friedel-Crafts acylation? — Benzene + CH₃COCl + AlCl₃ → Acetophenone
14. Which of the following reagents would be used for the Friedel-Crafts acylation of benzene to form benzophenone? — Benzoyl chloride and AlCl₃
15. The directive influence of a substituent can be explained by considering resonance and inductive effects on the stability of the: — Sigma complex (arenium ion) intermediate
16. In the Friedel-Crafts alkylation of benzene with methyl chloride, the electrophile is: — CH₃⁺
17. When benzene is reacted with carbon tetrachloride (CCl₄) in the presence of AlCl₃, the product is: — Benzotrichloride
18. The Friedel-Crafts reaction is generally not applicable to aromatic compounds containing which type of substituents? — Electron-withdrawing groups
19. The reaction of benzene with acetyl chloride in the presence of AlCl₃ yields: — Acetophenone
20. What product is formed when benzene is treated with acetyl chloride and AlCl₃, followed by hydrolysis? — Acetophenone
21. What is the correct order of reactivity of halobenzenes in Friedel-Crafts alkylation? — Iodobenzene > Bromobenzene > Chlorobenzene > Fluorobenzene
22. The reaction of benzene with an alkyl halide in the presence of a Lewis acid catalyst is known as: — Friedel-Crafts alkylation
23. Which of the following is a common Lewis acid catalyst used in Friedel-Crafts reactions? — FeCl₃
24. The deactivating effect of the cyano group (-CN) in electrophilic aromatic substitution is due to: — Both inductive and resonance effects, with inductive effect being dominant
25. Compared to Friedel-Crafts alkylation, Friedel-Crafts acylation is generally preferred because: — It does not suffer from polyacylation due to the deactivating nature of the acyl group.
26. The directive influence of a substituent on electrophilic aromatic substitution is primarily determined by: — Its ability to donate or withdraw electron density from the ring
27. In the electrophilic substitution of phenol, which positions are most reactive? — Ortho and para positions
28. Consider the nitration of chlorobenzene. The major products are ortho and para isomers. This indicates that the chlorine atom is: — Ortho, para-directing and deactivating
29. The directive influence of the alkyl group (-R) in electrophilic aromatic substitution is: — Ortho, para-directing and activating
30. Which of the following carbocations is most stable and likely to form in a Friedel-Crafts alkylation if possible? — Tertiary butyl carbocation
31. In the Friedel-Crafts reaction, the aromatic ring acts as a: — Nucleophile
32. Which reaction involves the formation of a sigma complex as an intermediate? — Electrophilic aromatic substitution
33. Friedel-Crafts acylation is an example of which type of reaction mechanism? — Electrophilic addition-elimination
34. When anisole (methoxybenzene) is subjected to nitration, the major product is: — p-Nitroanisole
35. When toluene undergoes nitration, the major product formed is: — p-Nitrotoluene
36. When a monosubstituted benzene is subjected to electrophilic aromatic substitution, the incoming electrophile usually attacks at positions directed by the substituent. What is the directive influence of an electron-donating group (EDG)? — Ortho, para-directing and activating
37. What is the directive influence of an electron-withdrawing group (EWG) in electrophilic aromatic substitution? — Meta-directing and deactivating
38. The nitro group (-NO₂) is a strong deactivator and a: — Meta-director
39. The carbocation formed in the Friedel-Crafts alkylation of benzene with n-propyl chloride is: — Secondary carbocation
40. Which type of catalyst is typically used in Friedel-Crafts alkylation and acylation reactions? — Lewis acids
41. In the sulfonation of benzene, what is the electrophile? — SO₃
42. What is the reason behind the ortho, para-directing nature of the methoxy group (-OCH₃)? — Resonance electron donation
43. Which of the following is a characteristic feature of Friedel-Crafts acylation that makes it superior to alkylation for controlled synthesis? — The acyl group is deactivating, preventing polyacylation.
44. What is the main limitation of Friedel-Crafts alkylation regarding polyalkylation? — The alkyl group is activating, making the product more reactive than the starting material.
45. The use of excess Lewis acid in Friedel-Crafts alkylation is sometimes necessary because: — The catalyst gets complexed with the product.
46. Why is aniline not suitable for Friedel-Crafts reactions? — The amino group reacts with the Lewis acid catalyst, deactivating it.
47. Halogens (like Cl, Br) are ortho, para-directors but are deactivating. Why? — They withdraw electron density inductively but donate electron density via resonance.
48. What is the primary reason for the rearrangement of carbocations in Friedel-Crafts alkylation? — To form a more stable carbocation (e.g., secondary to tertiary)
49. In Friedel-Crafts alkylation, what is the primary role of the Lewis acid catalyst (e.g., AlCl₃)? — To abstract a halide ion from the alkyl halide, generating a carbocation
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