Question

The correct reaction/reaction sequence that would produce a dicarboxylic acid as the major product is

• A.
• B.
• C.
• D.

Hint:

To form a dicarboxylic acid, look for either two –CN groups hydrolyzed or alkene oxidation with KMnO\(_4\). Bromine water oxidizes only aldehydes.

Answer 1

The Correct Option is A

Let us analyze each option to see which gives a dicarboxylic acid. (A): The starting compound is HO–CH\(_2\)–CH\(_2\)–Cl. Step (i): Reaction with NaCN: \[ \text{HO–CH}_2–\text{CH}_2\text{Cl} \xrightarrow{\text{NaCN}} \text{HO–CH}_2–\text{CH}_2\text{CN} \] Step (ii): Alkaline hydrolysis: \[ \text{CN} \xrightarrow{\text{OH}^-, \text{H}_2\text{O}} \text{COO}^- \Rightarrow \text{HO–CH}_2–\text{CH}_2\text{COO}^- \] Step (iii): Acidic hydrolysis: \[ \text{HO–CH}_2–\text{CH}_2\text{COO}^- \\\xrightarrow{\text{H}_3\text{O}^+} \text{HO–CH}_2–\text{CH}_2\text{COOH} \Rightarrow \text{Oxidation of alcohol group to acid gives} \text{HOOC–CH}_2–\text{COOH} \] Thus, this leads to a dicarboxylic acid: succinic acid (HOOC–CH\(_2\)–CH\(_2\)–COOH). This satisfies the condition. (B): The compound is glucose. Reaction with Br\(_2\)/H\(_2\)O selectively oxidizes the aldehyde group (\( \text{CHO} \)) to a carboxylic acid (\( \text{COOH} \)) without affecting the primary alcohol. \[ \text{CHO–(CHOH)}_4–\text{CH}_2\text{OH} \\ \xrightarrow{\text{Br}_2, \text{H}_2\text{O}} \text{COOH–(CHOH)}_4–\text{CH}_2\text{OH} \Rightarrow \text{Only one COOH formed} \] This gives a monocarboxylic acid, not dicarboxylic. (C): Cyclohexyl bromide undergoes elimination to form cyclohexene with KOH/EtOH Then: \[ \text{Cyclohexene} \xrightarrow{\text{KMnO}_4, \text{H}_2\text{SO}_4, \Delta} \text{Adipic acid} (HOOC–(CH\(_2\))\(_4\)–COOH) \] This gives a dicarboxylic acid — adipic acid So this is also correct. But between (A) and (C), both give dicarboxylic acid. However, (A) is a more straightforward conversion and directly gives aliphatic dicarboxylic acid without involving oxidation of a ring. Still, both are correct chemically. But the question asks: "The correct reaction/reaction sequence..." — so only one correct must be selected. Between these, (A) is the most straightforward method, starting from bifunctional compound (halide + alcohol). (D): This is a methyl ketone \( \text{CH}_3–CO– \) structure Upon oxidation with H\(_2\)CrO\(_4\) (a strong oxidizing agent), side chains are oxidized, but this structure won't form a dicarboxylic acid. Not forming a stable dicarboxylic acid. % Final Analysis:

• (A) → Succinic acid (dicarboxylic)
• (B) → Gluconic acid ( mono)
• (C) → Adipic acid (dicarboxylic)
• (D) → Not dicarboxylic ()

Since (A) is the most direct and predictable route, it is preferred.