Diazonium salts and their importance in synthetic organic chemistry - One Line Questions

1. At what temperature range is the diazotization reaction usually carried out to ensure the stability of the diazonium salt? — 0-5 °C
2. The diazonium group (-N₂⁺) is an excellent leaving group because it departs as: — A nitrogen molecule (N₂)
3. The Sandmeyer reaction is particularly useful for the synthesis of: — Aryl halides and cyanides
4. Which of the following compounds can be synthesized using diazonium salts as intermediates? — Aryl halides
5. When a diazonium salt reacts with water at higher temperatures, what is the major product formed? — Phenol
6. If an aromatic amine is treated with NaNO₂ and H₂SO₄ at low temperature, and then the resulting diazonium salt is treated with H₂O/heat, what is the main product? — Phenol
7. Azo coupling reactions typically occur between a diazonium salt and: — A phenol or an aromatic amine.
8. What type of dye is formed as a result of azo coupling reactions? — Azo dyes
9. The reaction of diazonium salts with SnCl₂/HCl leads to the formation of: — Hydrazines
10. The diazonium group can be replaced by iodine using potassium iodide. This reaction is an example of: — Sandmeyer reaction
11. The introduction of a cyano group (-CN) onto an aromatic ring using a diazonium salt is achieved through which reaction? — Sandmeyer reaction with CuCN
12. The Balz-Schiemann reaction is used to introduce which group onto an aromatic ring? — Fluorine
13. The Schiemann reaction is a specific name for the Balz-Schiemann reaction when introducing: — Fluorine
14. In the Gomberg-Bachmann reaction, a diazonium salt is reacted with another aromatic compound in the presence of: — A solvent like benzene or toluene
15. In the Sandmeyer reaction, which copper(I) salt is commonly used to introduce a chlorine atom onto the aromatic ring? — Copper(I) chloride (CuCl)
16. The synthesis of benzonitrile from aniline involves diazotization followed by reaction with: — CuCN
17. Azo compounds are characterized by the presence of two aryl groups attached to the azo linkage (-N=N-). What is the typical synthesis route for these compounds? — Diazotization of one primary amine followed by azo coupling with an activated aromatic compound.
18. The presence of the -N=N- group in azo compounds is responsible for their characteristic: — Color
19. The reaction of diazonium salts with sodium borohydride (NaBH₄) can lead to: — Reduction to the parent hydrocarbon
20. The synthesis of 4-bromophenol from 4-bromoaniline would involve diazotization followed by reaction with: — H₂O/heat
21. The replacement of the diazonium group by a hydroxyl group is often achieved by: — Heating the diazonium salt in aqueous acid.
22. The reaction of a diazonium salt with hypophosphorous acid (H₃PO₂) is a method for: — Replacing the diazonium group with hydrogen.
23. What is the Gattermann reaction, and how does it differ from the Sandmeyer reaction? — It uses copper powder instead of copper(I) salts and yields similar products.
24. The synthesis of iodobenzene from aniline involves the formation of a diazonium salt followed by reaction with: — KI
25. The stability of diazonium salts is influenced by the aromatic ring. Electron-donating groups on the ring generally make the diazonium salt: — More stable.
26. Which of the following is an example of an azo dye? — Methyl orange
27. When benzene diazonium chloride is treated with potassium nitrite in the presence of copper, the product formed is: — Nitrobenzene
28. A primary aromatic amine is converted to a diazonium salt using nitrous acid generated in situ. What is the active species of nitrous acid? — NO⁺
29. The azo coupling reaction is an example of an electrophilic aromatic substitution where the diazonium ion acts as the: — Electrophile
30. Diazonium salts are important synthetic intermediates because they are versatile in undergoing: — Substitution reactions where the -N₂⁺ group acts as a good leaving group.
31. The decomposition of diazonium salts is often accompanied by the evolution of: — Nitrogen gas
32. When benzene diazonium chloride is heated with copper powder and HCl, what is the product? — Chlorobenzene
33. The reaction of benzene diazonium chloride with ethanol can lead to the formation of: — Benzene
34. What is the general formula for a diazonium salt? — R-N≡N⁺ X⁻
35. The Sandmeyer reaction is a crucial reaction involving diazonium salts. What is the typical outcome of the Sandmeyer reaction? — Replacement of the diazonium group with a halogen or cyanide group.
36. Which of the following is a characteristic reaction of diazonium salts that leads to the formation of azo compounds? — Azo coupling reaction
37. Which reaction allows for the conversion of an aniline derivative to a phenol derivative via a diazonium salt intermediate? — Hydrolysis of the diazonium salt
38. Which of the following diazonium salt reactions is primarily used for the synthesis of biaryls? — Gomberg-Bachmann reaction
39. Which of the following reactions involving diazonium salts is MOST suitable for preparing diarylamines? — Gomberg-Bachmann reaction
40. In the Balz-Schiemann reaction, the diazonium salt is treated with: — Tetrafluoroborate anion (BF₄⁻)
41. Diazotization is the process of converting primary aromatic amines into diazonium salts. What reagent is typically used for this reaction? — Sodium nitrite and hydrochloric acid
42. The pH conditions for azo coupling are important. Coupling with phenols usually occurs under slightly alkaline conditions, while coupling with aromatic amines occurs under: — Slightly acidic conditions.
43. Which of the following is NOT a typical synthetic application of diazonium salts? — Synthesis of aliphatic amines
44. In the context of diazonium salts, 'diazotization' refers to: — The conversion of a primary amine into a diazonium salt.
45. Which of the following is a key reason for the importance of diazonium salts in synthetic organic chemistry? — Their ability to replace the -N₂⁺ group with a variety of functional groups.
46. Which of the following statements about diazonium salts is FALSE? — They readily undergo electrophilic substitution on the aromatic ring.
47. Why are aliphatic diazonium salts less stable and generally not isolated? — They readily lose nitrogen gas to form carbocations.
48. Which of the following is a characteristic property of aromatic diazonium salts? — They decompose rapidly at higher temperatures.
49. What is the role of copper(I) salts in the Sandmeyer reaction? — To facilitate the substitution of the diazonium group.
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