Question

The IUPAC name of glyoxal is:

• A. 1,2-ethanedione
• B. ethane-1,2-dione
• C. ethane-1,2-dial
• D. Ethano-1,2-dial

Hint:

When naming compounds with two carbonyl groups, use "dione" and specify the positions of the carbonyl groups on the parent chain.

Answer 1

The Correct Option is B

Glyoxal Identification:
Glyoxal is the simplest dialdehyde, represented by the molecular formula OHC–CHO.
Its structure comprises a two-carbon backbone, with an aldehyde group (–CHO) bonded to each carbon.

IUPAC Nomenclature Application:
 1. The principal carbon chain consists of 2 atoms, yielding "ethane".
  2. The presence of two aldehyde groups dictates the use of the suffix “dial”.
  3. When identical functional groups are situated on distinct carbon atoms, locants specify their positions. However, for terminal aldehyde groups (–CHO), positional numbering is frequently omitted as they are inherently at the ends of the molecule.

Conclusion:
The IUPAC designation for glyoxal is ethane-1,2-dial.

Final Determination: Option 3: ethane-1,2-dial