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In the given reaction sequence CH3CHO ...

In the given reaction sequence
`CH_3CHO underset((ii)H_2O^+)overset((i) NaCN//HCl)(rarr)(A) underset("reagent")overset("Fenton")(rarr)(B)`, B will be

A

Acetic acid

B

Oxalic acid

C

Pyruvic acid

D

Citric acid

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given reaction sequence, we need to identify the product B after the specified reactions. Let's break it down step by step. ### Step 1: Reaction of Acetaldehyde with NaCN and HCl 1. **Starting Material**: We begin with acetaldehyde (CH₃CHO). 2. **Reagents**: The first step involves treating acetaldehyde with sodium cyanide (NaCN) in the presence of hydrochloric acid (HCl). 3. **Mechanism**: - NaCN dissociates into Na⁺ and CN⁻ ions. The CN⁻ acts as a nucleophile and attacks the electrophilic carbon of the carbonyl group in acetaldehyde. - This results in the formation of a cyanohydrin intermediate, where the nucleophile adds to the carbonyl carbon and the oxygen gets protonated by HCl. 4. **Product A**: The product formed after this reaction is 2-hydroxybutyronitrile (CH₃C(OH)(CN)H). ### Step 2: Acidic Hydrolysis of the Cyanohydrin 1. **Next Step**: The cyanohydrin (product A) is then treated with water (H₂O) in acidic conditions (H₃O⁺). 2. **Mechanism**: - The CN group undergoes hydrolysis to form a carboxylic acid. In this case, the cyanide group (CN) is converted into a carboxylic acid (COOH). - The hydroxyl group remains intact. 3. **Final Product A**: The resultant product after hydrolysis is 2-hydroxybutyric acid (CH₃C(OH)COOH). ### Step 3: Reaction with Fenton's Reagent 1. **Reagents**: The product A (2-hydroxybutyric acid) is then treated with Fenton's reagent, which typically consists of ferrous sulfate (FeSO₄) and hydrogen peroxide (H₂O₂). 2. **Mechanism**: - Fenton's reagent oxidizes the hydroxyl group on the alpha carbon (the carbon adjacent to the carboxylic acid) to form a ketone. - In this case, the secondary alcohol (2-hydroxybutyric acid) is oxidized to form pyruvic acid (CH₃C(=O)COOH). 3. **Final Product B**: The final product B after this oxidation step is pyruvic acid. ### Conclusion The final product B formed in the reaction sequence is **pyruvic acid (C)**.
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