Methyl ketones
Methyl ketones give the iodoform reaction with alkaline iodine, producing yellow triiodomethane and a carboxylate with one fewer carbon.
- Functional group
- RCOCH3
- Also known as
- methylketones, methyl ketone, CH3CO compounds, alkan-2-ones
Overview
Ketones containing the CH3CO- group.
Methyl ketones give the iodoform reaction with alkaline iodine, producing yellow triiodomethane and a carboxylate with one fewer carbon.
Identifiers
- Functional group
- RCOCH3
- Also known as
- methylketones, methyl ketone, CH3CO compounds, alkan-2-ones
Chemical identifiers
- SMILES
- CC(=O)C
Diagnostic tests
iodoform test
- Reagent
- iodine in alkaline solution
- Conditions
- Add iodine followed by aqueous alkali and warm gently in a water bath.
- Positive observation
- a pale-yellow precipitate of triiodomethane forms
- Negative observation
- no pale-yellow precipitate forms
- Interpretation
- A positive result supports the presence of the CH3CO- group in a methyl ketone.
- Scope
- Methyl ketones give the characteristic triiodomethane precipitate.
- Limitations
- Not unique to methyl ketones: ethanol, ethanal and methyl secondary alcohols also give a positive result.
- Evidence
- textbook core
Related compounds
- Propanone
The simplest ketone, connecting carbonyl addition with secondary-alcohol formation.
- Butan-2-one
An unsymmetrical ketone whose reduction creates a stereogenic centre.
- Pentan-2-one
Pentan-2-one is an organic compound with the molecular formula C5H10O.
- Acetophenone
An aromatic methyl ketone with different groups on either side of its carbonyl.
- 4-Methylpentan-2-one
4-Methylpentan-2-one is an organic compound with the molecular formula C6H12O.
Connected reactions
- Iodoform reaction: Methyl ketones → Triiodomethane products
Alkaline iodine converts methyl ketones into yellow triiodomethane and a carboxylate with one fewer carbon.
References
- Pearson Edexcel International Advanced Level Chemistry Practical GuidePearson Education Limited · Pearson qualifications · 2018
Official Pearson practical guidance for organic qualitative tests, including bromine water, acidified dichromate, silver nitrate, carbonyl reagents and the iodoform reaction.
- PubChem Compound Summary: Propanone (CID 180)National Center for Biotechnology Information · PubChem
Identity, molecular formula, molecular weight and aliases retrieved via PUG REST on 2026-09-08.
- PubChem Compound Summary: Butan-2-one (CID 6569)National Center for Biotechnology Information · PubChem
Identity, molecular formula, molecular weight and aliases retrieved via PUG REST on 2026-09-08.
- PubChem Compound Summary: Pentan-2-one (CID 7895)National Center for Biotechnology Information · PubChem
Identity, molecular formula, molecular weight and aliases retrieved via PUG REST on 2026-09-08.
- PubChem Compound Summary: Acetophenone (CID 7410)National Center for Biotechnology Information · PubChem
Identity, molecular formula, molecular weight and aliases retrieved via PUG REST on 2026-09-08.
- PubChem Compound Summary: 4-Methylpentan-2-one (CID 7909)National Center for Biotechnology Information · PubChem
Identity, molecular formula, molecular weight and aliases retrieved via PUG REST on 2026-09-08.