Statement I: Primary aliphatic amines react with HNO2 to give unstable diazonium salts.
Statement II: Primary aromatic amines react with HNO2 to form diazonium salts which are stable even above 300 K.
Choose the most appropriate answer from the options given below:
Statement I: Primary aliphatic amines react with HNO2 to give unstable diazonium salts.
Statement II: Primary aromatic amines react with HNO2 to form diazonium salts which are stable even above 300 K.
Choose the most appropriate answer from the options given below:
- Both Statement I and Statement II are correct.
- Both Statement I and Statement II are incorrect
- Statement I is correct but Statement II is incorrect.
- Statement I is incorrect but Statement II is correct.
The Correct Option is C
Solution and Explanation
Statement I Explanation: Primary aliphatic amines react with nitrous acid (HNO2) to form diazonium salts. However, these diazonium salts are unstable at room temperature and tend to release nitrogen gas, leading to the formation of alcohols or other by-products. Therefore, Statement I is correct.
Statement II Explanation: Primary aromatic amines, such as aniline, react with nitrous acid to form diazonium salts. Unlike aliphatic diazonium salts, aromatic diazonium salts are typically stable at low temperatures (around 273 K) but decompose at higher temperatures (above 300 K) to yield phenols or other products. Hence, Statement II is incorrect because the stable nature of these salts is only at lower temperatures, not above 300 K.
Therefore, the correct answer is: Statement I is correct but Statement II is incorrect.
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Concepts Used:
Preparation of Amines
- Reduction of nitro compounds: Nitro compounds are reduced to amines by reduction with metals in an acidic medium or by passing them through hydrogen gas in the presence of finely divided nickel, palladium, or platinum.
- Ammonolysis of alkyl halides: Alkyl benzyl halide undergoes a nucleophilic substitution reaction while reacting with an ethanolic solution of ammonia where the halogen atom is replaced by an amino group and this process of splitting of the C-X bond by an ammonia molecule is called ammonolysis.
- Reduction of Nitriles: On reduction of nitriles with lithium or aluminum hydride or catalytic hydrogenation are used.
- Reduction of amides: On reduction, the amides with lithium aluminum hydride yield amines.
- Gabriel phthalimide synthesis: Gabriel synthesis is used to prepare primary amines. Phthalimidewhen treated with ethanolic potassium hydroxide, forms potassium salt of phthalimide which when heated with alkyl halide followed by alkaline hydrolysis leads to the formation of the corresponding primary amine.
- Hoffmann bromamide degradation reaction: In the Hoffmann bromamide degradation reaction, the transfer of an alkyl or aryl group takes place from the carbonyl carbon of the amide to the nitrogen atom. The amine so formed, therefore, contains one carbon less than that present in the initial amine.