Question

The IUPAC name of ($CH_3-CH_2-CHO$) is:

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

Hint:

Draw out the full structure of $CH_3-CH_2-CHO$ first and count every carbon in the main chain, including the carbon that is part of the CHO group itself, since that carbon is always counted as carbon number one for this functional group. Once the chain length and the position of the functional group are fixed, the correct suffix follows directly from the standard IUPAC naming rules for this group. Watch out for options describing a different functional group entirely, like an alcohol or a ketone, since those are easy traps if the group in the structure is misread.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
IUPAC nomenclature follows a set of rules to name organic compounds based on the longest carbon chain containing the principal functional group.
Step 2: Detailed Explanation:
1. Identify the functional group: The group \(-CHO\) represents an aldehyde.
2. Count the longest carbon chain: The chain has 3 carbon atoms (including the carbon in the aldehyde group). The root word for 3 carbons is "prop".
3. Identify the saturation: Since there are only single bonds between the carbons in the chain, the primary suffix is "an".
4. Add the secondary suffix: For aldehydes, the secondary suffix is "al".
5. Combine: Prop + an + al = Propanal.
Note: Propanone is a ketone (3 carbons), Propanoic acid has a \(-COOH\) group, and Ethanol is a 2-carbon alcohol.
Step 3: Final Answer:
The IUPAC name of the given compound is Propanal.

Answer 2

Concept:

• Match the compound directly against the general formula for an aldehyde, $R-CHO$, instead of walking through the naming rules one at a time.

Step 1: Compare the compound to the general aldehyde pattern.
An aldehyde always has the form $R-CHO$, where $R$ is the rest of the carbon chain. Here, $R = CH_3-CH_2-$.

Step 2: Count the total carbons, including the one in $CHO$.
$CH_3-CH_2-CHO$ has 3 carbons total, so the root name is "propan" (the same root used for propane).

Step 3: Attach the aldehyde ending directly.
Every aldehyde name ends in "-al", so "propan" becomes "propanal".

Final Answer: Propanal