Question

Draw structures for the following: (a) 2-Methylheptane (b) 4-Ethyl-2,2-dimethylhexane (c) 4 -Ethyl-3,4-dimethyloctane (d) \(2,4,4\) -Trimethylheptane (e) 3,3-Diethyl-2,5-dimethylnonane (f) 4-Isopropyl-3-methylheptane

Short answer

Draw each structure by identifying the main chain and adding substituents at specified positions.

Step-by-step solution

Understand the Nomenclature

To draw each structure, first identify the longest carbon chain based on the name suffix, which indicates the root structure (e.g., -heptane = 7 carbons). Identify any prefixes indicating additional groups (like methyl, ethyl, etc.) and their positions on the main chain.

Draw 2-Methylheptane

Start with the heptane backbone, a straight chain of 7 carbon atoms. Add a methyl group (-CH₃) to the second carbon on the main chain.

Draw 4-Ethyl-2,2-dimethylhexane

Start with a hexane backbone, a straight chain of 6 carbon atoms. Add two methyl groups (-CH₃) to the second carbon and an ethyl group (-CH₂CH₃) to the fourth carbon.

Draw 4-Ethyl-3,4-dimethyloctane

Begin with an octane backbone, a straight chain of 8 carbon atoms. Add methyl groups to the third and fourth carbons and an ethyl group to the fourth carbon.

Draw 2,4,4-Trimethylheptane

Use heptane as the base with 7 carbons. Attach a methyl group to the second carbon and two more methyl groups to the fourth carbon.

Draw 3,3-Diethyl-2,5-dimethylnonane

Start with nonane, a chain of 9 carbons. Add ethyl groups (-CH₂CH₃) to the third carbon and methyl groups (-CH₃) to the second and fifth carbons.

Draw 4-Isopropyl-3-methylheptane

Start with heptane, a chain of 7 carbons. Add an isopropyl group (-CH(CH₃)₂) to the fourth carbon and a methyl group to the third carbon.

Cross-check and Number Carbon Chains

Verify that each alkyl group is positioned on the correct carbon in the main chain, ensuring that you followed IUPAC naming rules and all substituents are attached appropriately.

Key concepts

IUPAC Naming Rules

When it comes to naming alkanes in organic chemistry, the IUPAC (International Union of Pure and Applied Chemistry) naming rules stand as a standardized system. The purpose is to provide a unique and universal name for each structure. Here's how it works:

• Identify the longest carbon chain as the root name. This chain rules the naming process as it indicates the number of carbons (e.g., heptane for 7 carbons).
• Determine the substituent groups attached to this main carbon chain, noting them as prefixes in the name.
• Number the carbon atoms in such a way that substituents receive the lowest possible numbers.
• List substituents in alphabetical order when writing the full compound name, despite their position numbers.

This system ensures that, regardless of who draws the structure, everyone reaches the same conclusion for its naming. This mutual understanding helps chemists communicate effectively worldwide.
Following these rules, structures from "4-Ethyl-2,2-dimethylhexane" to "3,3-Diethyl-2,5-dimethylnonane" can be correctly identified and named with confidence.

Organic Chemistry Structures

Understanding organic chemistry structures involves visualizing the arrangement of atoms in a molecule. In alkanes, carbon atoms connect in a chain and hydrogen atoms fill the remaining valences.

• Each carbon atom can form four covalent bonds, giving it the ability to bind with other carbon atoms, hydrogen, or functional groups.
• Structural formulas show these connections, illustrating the bonding between atoms in a manner that's easy to follow.
• The chains and branches are formed based on the presence of different substituents or functional groups attached to the main carbon chain.

For example, in the compound "2-Methylheptane," the main structure is a straight chain of seven carbon atoms, with a single methyl group attached to the second carbon. Learning to interpret these structures enables you to draw any alkane using just the IUPAC name as a guide.

Carbon Chains

Carbon chains form the backbone of organic compounds, crucial for defining their structure and properties. In alkanes, these are saturated chains with only single bonds.

• A straight carbon chain (like in "heptane") involves carbon atoms linearly connected, forming the longest continuous structure in the molecule.
• Branched chains result from substituents like methyl or ethyl groups, creating side chains from the main carbon skeleton.
• Understanding carbon chains is critical because it directly impacts the compound's chemical behavior, including its boiling and melting points.

For instance, in "4-Ethyl-3,4-dimethyloctane," the longest chain is an octane, and the addition of ethyl and methyl groups at specific positions creates branches that define its unique structure. Mastery of identifying and drawing carbon chains makes working with organic compounds significantly more intuitive.