Q48. The optimum pH for carrying out the reaction of aldehyde with hydroxylamine to form oxime is:

Q: What is the correct answer for CUET UG Chemistry Q48?

The correct answer is b. The reaction of an aldehyde (or ketone) with hydroxylamine (NH₂OH) to form an oxime involves two main steps:1. **Nucleophilic attack:** The nitrogen atom of hydroxylamine (a nucleophile) attacks the carbonyl carbon.2. **Elimination of water:** The intermediate undergoes dehydration to form the oxime.This reaction is acid-catalyzed, meaning the presence of some acid facilitates the elimination of

Q: Q48. The optimum pH for carrying out the reaction of aldehyde with hydroxylamine to form oxime is:

The correct answer is b. The reaction of an aldehyde (or ketone) with hydroxylamine (NH₂OH) to form an oxime involves two main steps:1. **Nucleophilic attack:** The nitrogen atom of hydroxylamine (a nucleophile) attacks the carbonyl carbon.2. **Elimination of water:** The intermediate undergoes dehydration to form the oxime.This reaction is acid-catalyzed, meaning the presence of some acid facilitates the elimination of

Q: What are the options for this CUET UG Chemistry question?

A. Ph = 1 · B. Ph = 4-5 · C. pH = 12 · D. Any pH

Question

Q48. The optimum pH for carrying out the reaction of aldehyde with hydroxylamine to form oxime is:

FirstInTest · Accepted Answer

The reaction of an aldehyde (or ketone) with hydroxylamine (NH₂OH) to form an oxime involves two main steps:1.  **Nucleophilic attack:** The nitrogen atom of hydroxylamine (a nucleophile) attacks the carbonyl carbon.2.  **Elimination of water:** The intermediate undergoes dehydration to form the oxime.This reaction is acid-catalyzed, meaning the presence of some acid facilitates the elimination of water by protonating the oxygen atom of the hydroxyl group. However, the pH must be carefully controlled:-   **At very low pH (highly acidic, e.g., pH 1):** The nucleophile, hydroxylamine, will get protonated (NH₃⁺OH). This protonated form is no longer nucleophilic, effectively stopping the initial nucleophilic attack step.-   **At very high pH (highly basic, e.g., pH 12):** The nucleophilicity of hydroxylamine is retained, but the protonation of the oxygen (which is crucial for the dehydration step to make water a good leaving group) is hindered. Thus, the elimination of water becomes very slow.Therefore, an **optimum slightly acidic pH (typically around 4-5)** is required. At this pH, there is enough acid to catalyze the dehydration step without excessively protonating the hydroxylamine and diminishing its nucleophilicity.

Answer

Ph = 1

Answer

Ph = 4-5

Answer

pH = 12

Answer

Any pH

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