Question

Formula of Hinsberg reagent?

• A. \(\text{C}_6\text{H}_5\text{SOCl}\)
• B. \(\text{C}_6\text{H}_5\text{SO}_2\text{Cl}\)
• C. \(\text{C}_6\text{H}_5\text{SOCl}_2\)
• D. \(\text{C}_6\text{H}_5\text{SO}_2\text{Cl}_2\)

Hint:

In the Hinsberg test, a \(1^\circ\) amine forms a sulfonamide that is soluble in alkali (due to an acidic hydrogen on N). A \(2^\circ\) amine forms a sulfonamide insoluble in alkali. A \(3^\circ\) amine does not react.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The Hinsberg test is a standard chemical test used to distinguish between primary, secondary, and tertiary amines. It relies on the reaction of these amines with a specific chemical reagent known as the Hinsberg reagent.
Step 2: Key Formula or Approach:
This is a factual knowledge question. The approach is to correctly recall the chemical name and subsequent molecular formula of the Hinsberg reagent.
Step 3: Detailed Explanation:
The chemical name for the Hinsberg reagent is benzenesulfonyl chloride.
Let's break down its structure to find the formula:
- "benzene" provides the phenyl ring: \(\text{C}_6\text{H}_5-\)
- "sulfonyl chloride" provides the functional group: \(-\text{SO}_2\text{Cl}\)
Combining these parts gives the molecular formula: \(\text{C}_6\text{H}_5\text{SO}_2\text{Cl}\).
Let's evaluate the options:
- A) \(\text{C}_6\text{H}_5\text{SOCl}\): This is benzenesulfinyl chloride, which has one less oxygen. Incorrect.
- B) \(\text{C}_6\text{H}_5\text{SO}_2\text{Cl}\): This perfectly matches benzenesulfonyl chloride. Correct.
- C) & D): These formulas represent chemically invalid or non-standard structures for this context.
Step 4: Final Answer:
The correct formula for Hinsberg's reagent is \(\text{C}_6\text{H}_5\text{SO}_2\text{Cl}\).