Question

Identify the correct IUPAC name of the compound: $\text{CH}_3\text{–CH}_2\text{–CHO}$

• A. Propanone
• B. Propanal
• C. Propanoic acid
• D. Propene

Hint:

The carbon in the aldehyde group (\(\text{–CHO}\)) is always counted as part of the main carbon chain.
It is also assigned position number 1 during numbering.
Therefore, a three-carbon chain containing \(\text{–CHO}\) is simply named propanal, and no locant number is needed.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The goal is to determine the correct systematic IUPAC name for the given organic molecular structure.

Step 2: Key Formula or Approach:
To name an organic compound, identify the longest continuous carbon chain, determine the principal functional group, and assign the appropriate suffixes and prefixes.
\[ \text{IUPAC Name} = \text{Word Root} + \text{Primary Suffix} + \text{Secondary Suffix} \]

Step 3: Detailed Explanation:

• Counting the Carbons: The given structure is \(\text{CH}_3\text{–CH}_2\text{–CHO}\). There are three carbon atoms in the longest continuous chain.
  
• Determining the Word Root: A three-carbon chain corresponds to the word root "prop".
  
• Determining the Primary Suffix: The carbon atoms are linked by single bonds, which means the hydrocarbon chain is saturated. The primary suffix is therefore "an".
  
• Identifying the Functional Group: The functional group present is \(\text{–CHO}\), which is an aldehyde group.
  
• Determining the Secondary Suffix: The secondary suffix for an aldehyde functional group is "-al".
  
• Combining the Components: Adding the root, primary suffix, and secondary suffix gives: \(\text{prop} + \text{an} + \text{al} = \text{propanal}\).
  
• Eliminating Other Options: Propanone is a ketone, propanoic acid is a carboxylic acid, and propene is an alkene. None of these match the aldehyde structure.
  

Step 4: Final Answer:
The correct IUPAC name for the given compound is Propanal, which is represented by option (B).