Understanding the IUPAC Naming of Simple Alkanes

The question asks for the IUPAC (International Union of Pure and Applied Chemistry) name of the compound with the structural formula CH₃CH₂CH₃.

This compound is a simple alkane. Alkanes are saturated hydrocarbons, meaning they contain only single bonds between carbon atoms and are composed solely of hydrogen and carbon atoms. Their general formula is \(C_nH_{2n+2}\), where 'n' is the number of carbon atoms.

Steps to Determine the IUPAC Name

To find the IUPAC name of a simple straight-chain alkane like CH₃CH₂CH₃, we follow these steps:

1. Count the number of carbon atoms in the main chain.
2. Identify the root name based on the number of carbon atoms.
3. Add the suffix '-ane' to the root name, as it is an alkane.

Counting Carbon Atoms and Identifying the Root Name

Let's look at the given structure: CH₃CH₂CH₃. We can see there are three carbon atoms connected in a chain:

• Carbon 1: CH₃
• Carbon 2: CH₂
• Carbon 3: CH₃

So, there are a total of 3 carbon atoms.

The root names for the first few number of carbon atoms in alkanes are:

Since the compound has 3 carbon atoms, the root name is "Prop-".

Adding the Suffix '-ane'

As the compound is an alkane (all single bonds between carbons, following the formula \(C_nH_{2n+2}\) with \(n=3\), which gives \(C_3H_{2 \times 3 + 2} = C_3H_8\)), we add the suffix '-ane' to the root name.

Root name: Prop-

Suffix: -ane

Combining them gives the IUPAC name: Propane.

Evaluating the Options

Let's quickly review the given options based on the number of carbon atoms:

• Pentane: This alkane has 5 carbon atoms (C₅H₁₂).
• Methane: This alkane has 1 carbon atom (CH₄).
• Butane: This alkane has 4 carbon atoms (C₄H₁₀).
• Propane: This alkane has 3 carbon atoms (C₃H₈).

The compound CH₃CH₂CH₃ has 3 carbon atoms, which matches the structure of propane.

Conclusion on IUPAC Naming

Based on the IUPAC nomenclature rules for alkanes, the compound CH₃CH₂CH₃ with 3 carbon atoms in a continuous chain is named Propane.

Revision Table: Alkane IUPAC Naming

Additional Information on Alkanes and IUPAC Nomenclature

Alkanes form a homologous series, where successive members differ by a \(CH_2\) group. They are relatively unreactive and are often referred to as paraffins (from the Latin words 'parum affinis', meaning 'little affinity').

Key points about IUPAC nomenclature for alkanes:

• Find the longest continuous carbon chain, which determines the root name.
• Number the carbon atoms in the main chain from the end nearest to any substituents.
• Identify and name the substituents (like methyl, ethyl, etc.).
• If the same substituent appears more than once, use prefixes like di-, tri-, tetra-, etc.
• List substituents in alphabetical order.
• Use hyphens to separate numbers and words, and commas to separate numbers.

For simple straight-chain alkanes, the process is straightforward: count carbons for the root and add '-ane'.