Problem 96 - A Complete Resource Book in Chemistry for JEE Main

Question

The No. of C-atoms present in Paracetamol?

Step-by-Step Solution

Answer

Paracetamol contains 8 carbon atoms.

Step 1: Understanding the Chemical Structure

Paracetamol is known by its IUPAC name, N-(4-hydroxyphenyl)acetamide. The structure consists of a benzene ring (a phenyl group with a hydroxy group) and an acetamide group attached to it.

Step 2: Identifying Carbon Atoms in the Benzene Ring

The benzene ring in Paracetamol is a phenyl group, which consists of 6 carbon atoms. This is a common structure that can be identified by the hexagonal arrangement of carbon atoms.

Step 3: Identifying Carbon Atoms in the Acetamide Group

The acetamide group contributed to the structure includes one carbon atom in the carbonyl (C=O) and one in the adjacent methyl group (CH3). Therefore, there are 2 carbon atoms in the acetamide group.

Step 4: Calculating the Total Number of Carbon Atoms

Now, add the carbon atoms from the benzene ring and the acetamide group. The benzene ring has 6 carbon atoms and the acetamide group adds 2 more carbon atoms. Thus, the total number of carbon atoms in Paracetamol is 6 + 2 = 8.

Key Concepts

IUPAC Nomenclature

The IUPAC nomenclature system is a standardized method for naming chemical compounds. In this system, every chemical has a unique IUPAC name, which reflects its molecular structure. For Paracetamol, the IUPAC name is N-(4-hydroxyphenyl)acetamide. This name provides specific information about its chemical structure:

• "N-" indicates that a substituent is attached to the nitrogen atom.
• "4-hydroxyphenyl" refers to a benzene ring with a hydroxy group (-OH) attached to the fourth carbon in the ring.
• "Acetamide" suggests the presence of an acetamide group, consisting of a carbonyl group (C=O) bonded to a nitrogen atom.

This systematic naming helps chemists easily understand the molecule's structure and its functional groups.

Benzene Ring Carbon Atoms

The benzene ring is a fundamental component in many organic compounds, including Paracetamol. It consists of six carbon atoms arranged in a hexagonal ring. In organic chemistry, we often refer to this as a 'phenyl group' when it's part of a larger structure.

• Each corner of the hexagon represents a carbon atom.
• The ring has alternating single and double bonds creating a stable aromatic system.
• Benzene is particularly stable due to the delocalization of electrons across the ring, helping to distribute energy evenly.

In Paracetamol, the benzene ring is modified with a hydroxy group (-OH) at one of its carbon atoms, adding to its chemical functionality and reactivity.

Acetamide Group

The acetamide group is another vital component of Paracetamol's structure. It's a specific type of amide, which includes the following:

• A carbonyl group (C=O), where carbon is double-bonded to oxygen.
• A methyl group (CH3), a simple alkyl group consisting of one carbon atom and three hydrogen atoms.
• A nitrogen atom that links the carbonyl and methyl groups to the rest of the molecule.

Amides like acetamide are crucial in organic chemistry and biological processes because they form through reactions between carboxylic acids and amines. In Paracetamol, the acetamide group contributes two carbon atoms to the overall structure, playing a significant role in its pharmacological activity.