Question

The correct structure of the drug paracetamol is (a) CC(=O)Nc1ccc(O)cc1 (b) NC(=O)c1ccc(Cl)cc1 (c) NC(=O)c1ccc(O)cc1 (d) none of these

Short answer

Option (a) is the correct structure of paracetamol.

Step-by-step solution

Understand the SMILES Notation

SMILES (Simplified Molecular Input Line Entry System) is a notation that uses letters and symbols to represent the structure of a chemical compound. It is important to be familiar with how functional groups and bonds are represented.

Analyze Option (a)

Option (a) is represented as CC(=O)Nc1ccc(O)cc1. This notation translates to an acetamide group (CH₃CO-), followed by an aromatic ring with a hydroxyl group at the para position. This matches the structure of paracetamol.

Analyze Option (b)

In option (b), NC(=O)c1ccc(Cl)cc1, the structure has an amide group but contains a chlorine substituent on the aromatic ring, which does not correspond to the structure of paracetamol.

Analyze Option (c)

Option (c) is given as NC(=O)c1ccc(O)cc1. This notation translates to a primary amide (NH₂CO-) with a phenolic hydroxyl group. However, it lacks the additional methyl group found in paracetamol.

Determine the Correct Option

Compare all options and recall that paracetamol's structure is characterized by an acetamide group and a hydroxyl group in the para position of the benzene ring. Option (a) is correct as it aligns with these structural features.

Key concepts

SMILES notation

SMILES, which stands for Simplified Molecular Input Line Entry System, is a way to represent a chemical structure using short string codes. It’s like a language for molecules that helps scientists and computers quickly understand what a molecule looks like without needing an actual image. In SMILES notation, each letter or symbol stands for a part of the molecule.
For example:

• Atoms are written as their normal atomic symbols, like C for carbon or O for oxygen.
• Single bonds are simply implied and usually not written, while double (\(=\)) and triple bonds (\(#\)) are explicitly shown.
• Branches and cyclic rings are expressed using special characters like parentheses and numbers.

With paracetamol, the SMILES code helps us identify its structure quickly. This makes it an invaluable tool in modern chemistry.

chemical structure analysis

Chemical structure analysis is the process of understanding and interpreting how a molecule is built. This involves not only recognizing functional groups within the molecule but also understanding how these groups are connected and oriented.
When examining a SMILES string like for paracetamol, we look at each part of the structure:

• The chain of atoms and how they are bonded.
• Any functional groups attached, such as acetamide or hydroxyl groups.
• Special configurations, like aromatic rings.

With this type of analysis, chemists can deduce important properties of the compound, predict its behavior in reactions, and understand its potential effects as in the case of drug design.

acetamide group

The acetamide group is a key feature in many compounds, including paracetamol. It consists of a carbon atom double-bonded to an oxygen (\(=O\)), single bonded to a nitrogen group (\(NH\)), and connected to a methyl group (\(CH_3\)).
This group is important because:

• It is polar, which can influence how the molecule interacts with water and other substances.
• The acetamide contributes to the molecule's stability and solubility properties.

In the SMILES notation for paracetamol, this group is part of the "CC(=O)N" part, indicating its role in the overall structure of the drug.

aromatic ring

An aromatic ring is a type of stable ring structure that contains alternating single and double bonds, usually involving six carbon atoms, like in a benzene ring. It’s important because:

• Aromatic rings provide stability to the molecule due to electron delocalization.
• They are commonly found in many drug molecules.
• The chemical reactivity of these rings is unique, making them useful in biological systems.

In paracetamol, this ring is represented as "c1ccc(O)cc1" in the SMILES, where "c" indicates carbons in an aromatic ring. The presence of the hydroxyl group on the aromatic ring further adds to its chemical characteristics.

hydroxyl group

The hydroxyl group, characterized by the (\(-OH\)) part, is a common functional group in organic chemistry. In paracetamol, it is a crucial part of the molecule's identity.
Here are some properties and effects of the hydroxyl group:

• It is polar, making molecules that contain it more hydrophilic (water-loving).
• It can form hydrogen bonds, which are important for solubility and reactivity.
• The hydroxyl group influences the acidity of compounds when attached to an aromatic ring, like in paracetamol.

In the SMILES for paracetamol, the hydroxyl group's presence is indicated by "(O)", and its placement on the aromatic ring is essential for the compound's pharmacological effectiveness.