Question

Draw structures corresponding to the following names: (a) Aniline (b) Phenol (c) \(o\) -Xylene (d) 2,4,6 -Trinitrobenzene (e) \(p\) -Chlorobenzoic acid (f) \(m\) -Nitroaniline (g) \(o\) -Chlorobenzaldehyde (h) Anisole (methoxybenzene)

Short answer

Draw each structure starting with a benzene ring and add specified groups to the appropriate positions.

Step-by-step solution

Understanding Aniline

Aniline is a benzene ring with an amino group \(\text{-NH}_2\) attached to it. To draw it, sketch a hexagonal benzene ring and attach \(\text{-NH}_2\) to one of the carbon atoms.

Sketching Phenol

Phenol is composed of a benzene ring with a hydroxyl group \(\text{-OH}\) attached. Draw a benzene hexagon and place the \(\text{-OH}\) group on one of its carbons.

Drawing \\(o\\)-Xylene

Ortho-xylene has two methyl groups attached to the benzene ring at adjacent (ortho) positions. Draw a benzene ring and add methyl groups \(\text{-CH}_3\) to two adjacent carbon atoms.

Constructing 2,4,6-Trinitrobenzene

This structure involves a benzene ring with three nitro groups \(\text{-NO}_2\) at the 2, 4, and 6 positions. First, draw the benzene ring, then add the \(\text{-NO}_2\) groups at the specified positions around the ring.

Designing \\(p\\)-Chlorobenzoic Acid

Para-chlorobenzoic acid has a chlorine atom and a carboxylic acid group \(\text{-COOH}\) attached to the opposite ends of a benzene ring. Position the \(\text{-Cl}\) group and the \(\text{-COOH}\) group on the para positions (carbon atoms 1 and 4).

Writing \\(m\\)-Nitroaniline

Meta-nitroaniline has a nitro group \(\text{-NO}_2\) and an amino group \(\text{-NH}_2\) on a benzene ring, separated by one carbon atom (meta position). Draw the benzene ring, add \(\text{-NH}_2\) to one carbon, and \(\text{-NO}_2\) to the carbon two positions over.

Drawing \\(o\\)-Chlorobenzaldehyde

Ortho-chlorobenzaldehyde is a benzene with both an aldehyde group \(\text{-CHO}\) and a chlorine atom \(\text{-Cl}\) on adjacent carbons. Draw the benzene and attach \(\text{-CHO}\) and \(\text{-Cl}\) to adjacent carbon atoms.

Creating Anisole (Methoxybenzene)

Anisole, also known as methoxybenzene, is a benzene with a methoxy group \(\text{-OCH}_3\). Draw the benzene ring and attach \(\text{-OCH}_3\) to one carbon.

Key concepts

Aniline

Aniline is an essential compound in organic chemistry. It is characterized by a benzene ring directly attached to an amino group \(\text{-NH}_2\). This structure makes aniline integral in the preparation of dyes, drugs, and other aromatic compounds. To draw aniline:

• Begin by sketching a hexagonal benzene ring, a fundamental aromatic structure known for its alternating double bonds.
• Add an amino group \(\text{-NH}_2\) to one of the carbon atoms in the ring.

This attachment places the amino group in direct resonance with the benzene ring, stabilizing the aniline molecule and influencing its reactivity in substitution reactions.

Phenol

Phenol, also known as carbolic acid, combines a benzene ring with a hydroxyl group \(\text{-OH}\). The presence of the \(\text{-OH}\) group confers unique properties, such as acidity and increased reactivity, compared to other benzene derivatives. When drawing phenol:

• Sketch the familiar hexagonal benzene ring.
• Attach the hydroxyl group \(\text{-OH}\) to one of its carbon atoms.

The placement of the \(\text{-OH}\) group enhances the solubility and reactivity of phenol. This structure makes phenol a useful precursor in the production of plastics and pharmaceuticals, due to its ability to undergo further chemical transformations.

Benzene Substitution Patterns

Understanding benzene substitution patterns is crucial for identifying the positions at which groups are added around the benzene ring. These patterns are defined as ortho, meta, and para:

• **Ortho (o-)**: Substituents are adjacent on the benzene ring, at carbons 1 and 2.
• **Meta (m-)**: Substituents are separated by one carbon atom, at positions 1 and 3.
• **Para (p-)**: Substituents are opposite each other, located on carbons 1 and 4.

These patterns influence the chemical and physical properties of the compound. For instance, ortho-substituted compounds might exhibit unique steric effects compared to their meta or para counterparts. Recognizing these patterns helps in predicting the product of aromatic substitution reactions, essential for synthesizing a wide array of aromatic compounds.