Question

Draw structures corresponding to the following names: (a) 3-Methyl-2-nitrobenzoic acid (b) Benzene-1,3,5-triol (c) 3-Methyl-2-phenylhexane (d) \(o\) -Aminobenzoic acid (e) \(m\) -Bromophenol (f) \(2,4,6\) -Trinitrophenol (picric acid) (g) \(p\) -Iodonitrobenzene

Short answer

Draw each compound by placing functional groups at specified positions on benzene or alkane chains.

Step-by-step solution

Understand the Structure of 3-Methyl-2-nitrobenzoic acid

Begin by identifying the benzoic acid, which has a benzene ring with a carboxylic acid (\( -COOH \) group). Locate carbon 1, where the \( -COOH \) group is attached. From here, count around the ring. At position 2, add a \( -NO_2 \) group, and at position 3, add a methyl (\( -CH_3 \) group). Draw these on the benzene ring.

Draw Benzene-1,3,5-triol

Recognize that benzene forms the base structure. Add hydroxyl groups (\( -OH \) group) to carbon atoms 1, 3, and 5 on a benzene ring.

Structure of 3-Methyl-2-phenylhexane

Identify a hexane chain and number it from the end nearest the first substituent. At carbon 2, attach a phenyl group (\( C_6H_5 \) or benzene ring), and on carbon 3, add a methyl group (\( -CH_3 \)).

Draw o-Aminobenzoic acid

Start with the benzoic acid structure. The "o-" (ortho) indicates that the amino group (\( -NH_2 \)) is adjacent to the carboxylic acid group, which is at position 1. Therefore, place the \( -NH_2 \) group at position 2.

Draw m-Bromophenol

Begin with a phenol, which has a hydroxyl group (\( -OH \)) on the benzene ring. The "m-" (meta) means the bromine (\( -Br \)) is three positions away from the hydroxyl group, so it's on carbon 3 if \( -OH \) is at carbon 1.

Structure of 2,4,6-Trinitrophenol (Picric Acid)

Begin with a phenol. Add nitro groups (\( -NO_2 \)) on carbons 2, 4, and 6 of the benzene ring, with the \( -OH \) group at carbon 1.

Draw p-Iodonitrobenzene

Start with benzene. Use the "p-" (para) substitution pattern to place iodine (\( -I \)) and a nitro group (\( -NO_2 \)) opposite each other on the benzene ring.

Key concepts

Chemical Nomenclature

Chemical nomenclature is the systematic method of naming chemical compounds. Understanding this is crucial for identifying structures just from their names. In organic chemistry, names often reveal the structure of a compound by indicating the type and position of functional groups attached to the main structure.
There are a few key components to consider in organic chemical nomenclature:

• **Root Name**: This tells us the main carbon chain or ring structure. For example, "hexane" indicates six carbon atoms in a continuous line.
• **Substituents**: These are atoms or groups of atoms attached to the main chain/ring, like "methyl", "nitro", or "phenyl" groups.
• **Numbering**: This shows where substituents are located on the main structure. Numbers are assigned based on priority rules and smallest-number preference.
• **Prefixes and Suffixes**: Indicate the presence of functional groups. For instance, "-ol" denotes an alcohol group, and "-oic acid" points to a carboxylic acid.

By following these rules, chemists can derive a compound's structure just by reading its name. This method ensures consistent communication across the scientific community.

Benzene Derivatives

Benzene derivatives are a vital area of study in organic chemistry due to benzene's aromatic stability. Benzene is a six-carbon ring structure with alternating double bonds, also known as an aromatic ring.
The concept of benzene derivatives involves adding functional groups to the benzene ring. These groups can change the chemical property without altering the underlying stability of benzene. Substitutions on the benzene ring:

• **Ortho (o-)**: Substitute groups are adjacent or at a 1,2 relationship on the benzene ring.
• **Meta (m-)**: Substituents located at a 1,3 relationship or one carbon apart on the benzene ring.
• **Para (p-)**: Positioned opposite each other at a 1,4 relationship.

For example, in "o"-aminobenzoic acid, the amino group is adjacent to the carboxylic group in a benzene ring structure, indicating the ortho position. These positional descriptors help communicate structural relationships and properties, essential for predicting reactivity and interactions with other compounds.

Functional Groups

Functional groups are specific groups of atoms within molecules that determine the characteristic chemical reactions of those molecules. In an organic chemistry context, they provide insight into the chemical behavior of molecules.
Here are some common functional groups found in the exercises:

• **Carboxylic Acid (\( -COOH \))**: Found in benzoic acid derivatives, this group is known for its acidic properties and forms hydrogen bonds easily.
• **Hydroxyl Group (\( -OH \))**: Present in alcohols and phenols, influencing hydrophilicity and reactivity.
• **Amino Group (\( -NH_2 \))**: Found in amino acids, contributes to basicity and acts as a building block in protein synthesis.
• **Nitro Group (\( -NO_2 \))**: Known for electron-withdrawing properties, affecting reactivity and stability.
• **Halide Group (e.g., \( -Br \), \( -I \))**: Used in electrophilic and nucleophilic substitution reactions.

Understanding these groups is essential for determining compound properties and reactions. They play a critical role in how molecules interact in chemical processes.