Question

What is the IUPAC name of glyoxal?

• A. Propanedial
• B. Ethanedial
• C. 2-Methyl propanal
• D. Prop-2-enal

Hint:

Glyoxal is the simplest possible dialdehyde molecule in organic chemistry. Since a dialdehyde must contain at least two aldehyde carbon atoms (-CHO units), the smallest possible chain length is 2 carbons, which directly corresponds to the prefix "ethan-", making it ethanedial.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The problem requires us to determine the official IUPAC systematic name for the common chemical dialdehyde known as glyoxal.

Step 2: Key Formula or Approach:
According to IUPAC nomenclature rules for aliphatic dialdehydes: 1. Find the longest continuous carbon chain containing both aldehyde carbon atoms.
2. Count the total number of carbon atoms to identify the parent alkane name.
3. Replace the ending "-e" of the parent alkane with the suffix suffix "-dial".
4. Position numbers are not required for simple dialdehydes since the aldehyde groups (-CHO) are inherently located at the two ends of the chain.

Step 3: Detailed Explanation:
5. The chemical structure of glyoxal consists of two carbonyl carbon atoms bonded directly to each other, with each attached to a hydrogen atom: $$\text{CHO}\mathrel{-}\text{CHO}$$ 6. Counting the continuous chain, there are exactly 2 carbon atoms present.
7. The parent alkane with 2 carbon atoms is ethane.
8. Combining the parent alkane name with the dialdehyde functional suffix gives: $$\text{Ethane} + \text{dial} = \text{Ethanedial}$$

Step 4: Final Answer:
The official IUPAC name of glyoxal is ethanedial, which matches option (B).