Problem 10 - A Complete Resource Book in Chemistry for JEE Main

Question

Hinsberg reagent is (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NO}\) (b) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2} \mathrm{Cl}\) (c) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{SO}_{2} \mathrm{Cl}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{SO}_{3} \mathrm{H}\)

Step-by-Step Solution

Answer

The Hinsberg reagent is \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{SO}_{2} \mathrm{Cl}\), benzene sulfonyl chloride.

Step 1: Understanding the Question

We need to identify which of the given chemical compounds is known as the Hinsberg reagent. This reagent is specifically used in organic chemistry to distinguish primary, secondary, and tertiary amines.

Step 2: Analyzing the Options

Let's review each option:- (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NO}\) is nitrosobenzene.- (b) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{~N}_{2} \mathrm{Cl}\) is benzene diazonium chloride.- (c) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{SO}_{2} \mathrm{Cl}\) is benzene sulfonyl chloride.- (d) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{SO}_{3} \mathrm{H}\) is benzenesulfonic acid.

Step 3: Identifying the Correct Reagent

The Hinsberg reagent is a chemical compound that reacts with amines. It is well known to be benzene sulfonyl chloride, which is the chemical \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{SO}_{2} \mathrm{Cl}\). This reagent reacts with amines to form sulfonamides.

Key Concepts

Amines

Amines are a class of compounds in organic chemistry derived from ammonia by replacement of one, two, or all three hydrogen atoms with organic groups. They are categorized as primary (RNH₂), secondary (R₂NH), and tertiary (R₃N) amines based on the number of organic groups attached to the nitrogen atom.
This functional group is essential in many biological molecules, including amino acids. They are also crucial in synthetic applications due to their wide range of reactivity.

• Primary amines: Have one carbon-containing group attached (e.g., methylamine).
• Secondary amines: Have two carbon-containing groups (e.g., dimethylamine).
• Tertiary amines: Contain three carbon-containing groups (e.g., trimethylamine).

Amines can exhibit basicity due to the presence of the lone pair of electrons on nitrogen, making them act as Lewis bases. This property is instrumental when using reagents like the Hinsberg reagent for differentiation in experiments.

Sulfonamides

Sulfonamides are an essential class of organic compounds that can be synthesized using benzene sulfonyl chloride and amines. When benzene sulfonyl chloride reacts with primary or secondary amines, a sulfonamide compound forms.
The Hinsberg test utilizes this process to differentiate between amines:

• Primary amines react to form sulfonamides which are soluble in alkali solutions.
• Secondary amines yield sulfonamides that are insoluble.
• Tertiary amines don't react, leading to no formation of sulfonamides.

This test is a crucial aspect of organic analysis, allowing chemists to discern and classify amines effectively based on their reactivity and the solubility of their sulfonamide products.

Organic Chemistry

Organic chemistry is the branch of chemistry focused on the study of carbon-containing compounds, their properties, structures, and reactions. It forms the basis for understanding both numerous natural substances and a plethora of synthetic materials.
The discipline categorizes compounds into families based on functional groups, like alcohols, acids, amines, and more. Each group has characteristic reactions, aiding in the prediction of behavior in chemical reactions.
One of the fundamental tasks in organic chemistry is the identification of compounds through analytical techniques and reactions, such as the Hinsberg test, which is quintessential for determining the nature of amines.

Benzene Sulfonyl Chloride

Benzene sulfonyl chloride is a chemical compound with the formula exttt{C₆H₅SO₂Cl}. It is the active component in the Hinsberg reagent, widely used for its ability to engage in reactions with amines, leading to the formation of sulfonamides.
In the presence of benzene sulfonyl chloride, primary and secondary amines form solid sulfonamide derivatives, which can then be further analyzed based on their solubility in basic or acidic solutions.
This compound consists of a benzene ring bonded to a sulfonyl chloride group, making it highly reactive due to the presence of the electrophilic sulfur atom. Its role in distinguishing between amines cannot be overstated, as its reactivity properties allow clear and practical experimentation.