Question

The name 2 -ethylhexane is incorrect. Draw the carbon backbone and write the correct name for this molecule.

Short answer

The correct name is 3-ethylheptane.

Step-by-step solution

Understand the Current Naming

The name '2-ethylhexane' implies that there is a hexane (6 carbon) backbone, with an ethyl group (2 carbon) attached to the second carbon. However, this name is incorrect because it presents an inconsistency with the IUPAC naming rules.

Draw the Incorrect Structure

First, let's visualize what '2-ethylhexane' would suggest as a structure: A six-carbon chain (hexane) with an ethyl group (-CH2CH3) attached to the second carbon in the chain.

Identify the Parent Chain

To correctly name this molecule, we must find the longest continuous carbon chain, which should form the base name of the compound. In our attempt to draw '2-ethylhexane', the longest chain is actually 7 carbons, not 6.

Select the Correct Parent Name

Since the longest chain is 7 carbons, the base compound should be named heptane (not hexane). The structure derived from trying to follow the incorrect name suggests a heptane backbone, with a substituent.

Assign Numbering for Substitution

Number the longest chain (heptane) from the end nearest to a substituent. Here, the ethyl group appears on the third carbon of the heptane backbone.

Name the Substituent

With substitution on the third carbon, and knowing it is an ethyl group, the correct name should reflect the substitution as 3-ethylheptane.

Finalize the Structure and Name

After analyzing the corrected backbone based on the longest chain, the actual structure fits the IUPAC name of 3-ethylheptane, not 2-ethylhexane.

Key concepts

Organic Chemistry

When exploring organic chemistry, you delve into the fascinating world of carbon-containing compounds. This field of science is vast and covers the study of the structure, properties, reactions, and synthesis of organic compounds. These compounds mainly consist of carbon and hydrogen, but also include other elements such as oxygen, nitrogen, sulfur, and more. One of the key aspects of organic chemistry is understanding how these elements bond to form a wide variety of molecular structures.

Organic chemistry is integral to both nature and industry. It plays a vital role in the biological processes within living organisms and in the development and production of pharmaceuticals, plastics, fuels, and other essential materials. By learning organic chemistry, you begin to comprehend how molecular structures translate into the function and reactivity of substances, an essential skill for developing new and effective materials.

Alkanes

Alkanes are a fundamental class of hydrocarbons that consist exclusively of single bonds between carbon atoms. These compounds are saturated, meaning that each carbon atom forms the maximum number of bonds possible, typically four. As the simplest type of hydrocarbons, alkanes serve as a foundation for understanding more complex organic molecules.

When it comes to naming alkanes, the International Union of Pure and Applied Chemistry (IUPAC) provides specific rules. These rules help ensure consistency and reduce ambiguity in chemical nomenclature. Each alkane molecule consists of a carbon backbone with hydrogen atoms filling the remaining valences. Common alkanes include methane (CH₄), ethane (C₂H₆), propane (C₃H₈), and so forth; these names depend on the number of carbons in the longest continuous chain.

• Alkanes are named based on the longest carbon chain.
• Side groups or substituents require specific numbers and prefixes (e.g., methyl, ethyl).

Molecular Structure

In organic chemistry, understanding molecular structure is crucial for grasping how a molecule will behave in chemical reactions. At its core, the molecular structure describes how atoms are arranged in a molecule, including bond connections and angles. This arrangement impacts everything from reactivity to the physical state of a compound.

To visualize molecular structures, chemists often draw structural formulas, which depict how atoms connect within a given molecule. These diagrams help highlight the arrangement of carbon atoms and any functional groups or substituents attached. For example, the molecule initially named as "2-ethylhexane" must be drawn to accurately display the actual relation and connection of the carbon atoms, revealing the correct structure as "3-ethylheptane."

• Atoms are shown connected by lines representing bonds.
• The structure should reflect the longest carbon chain.

Carbon Chain Identification

Identifying the correct carbon chain is essential for naming organic compounds using IUPAC guidelines. The parent chain is the longest continuous chain of carbon atoms in the molecule, which determines the base name of the compound. This process involves some strategic examination of the structure to ensure accuracy in the name.

To identify the carbon chain:

• Look for the longest series of connected carbon atoms.
• Consider all possible chains to ensure you choose the one with the maximum number of carbons.

In the scenario of the molecule mentioned as "2-ethylhexane," identifying the longest chain revealed that, in fact, seven carbons are linked continuously, leading to the correct base name "heptane." This method helps ensure that compounds are not misnamed, avoiding confusion in scientific communication.