Ethanal
Ethanal is the aldehyde exception in the iodoform reaction because it contains the CH3CO- carbonyl pattern after oxidation state accounting.
- Formula
- C2H4O
- Functional group
- CH3CHO
- Molar mass
- 44.05 g/mol
- Also known as
- acetaldehyde, CH3CHO
Overview
Two-carbon aldehyde that gives the iodoform reaction.
Ethanal is the aldehyde exception in the iodoform reaction because it contains the CH3CO- carbonyl pattern after oxidation state accounting.
Identifiers
- Formula
- C2H4O
- Functional group
- CH3CHO
- Molar mass
- 44.05 g/mol
- Also known as
- acetaldehyde, CH3CHO
Chemical identifiers
- SMILES
- CC=O
- InChI
- InChI=1S/C2H4O/c1-2-3/h2H,1H3
- PubChem CID
- 177
Properties
- Melting Point
- -123.4 °C
- Boiling Point
- 20.8 °C
- Density
- 0.7834 g/cu cm at 18 °C
- Water solubility
- Miscible with water
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 is consistent with ethanal, the aldehyde that gives the iodoform reaction.
- Scope
- Ethanal is the aldehyde member of the iodoform-positive set.
- Limitations
- Not unique to ethanal: ethanol, methyl ketones and methyl secondary alcohols also give a positive result.
- Evidence
- textbook core
Related compounds
- Aldehydes
Ethanal is a two-carbon molecule-level member of the aldehyde family.
Connected reactions
- Iodoform reaction: Ethanal → Triiodomethane products
Ethanal gives triiodomethane and methanoate in the alkaline iodine iodoform reaction.
- Partial oxidation: Ethanol → Ethanal
Ethanol is oxidised to ethanal.
- Oxidation: Ethanal → Ethanoic acid
Ethanal is oxidised to ethanoic acid.
- Reduction: Ethanal → Ethanol
Ethanal is reduced to ethanol.
References
- PubChem Compound Summary for AcetaldehydeNational Center for Biotechnology Information · PubChem · 2026
Used for stable identifiers and basic compound metadata.
- Hazardous Substances Data Bank (HSDB): Ethanal — melting pointHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/177#section=Melting-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 3-4
- Hazardous Substances Data Bank (HSDB): Ethanal — boiling pointHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/177#section=Boiling-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 3-4
- Hazardous Substances Data Bank (HSDB): Ethanal — densityHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/177#section=Density. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Haynes, W.M. (ed.). CRC Handbook of Chemistry and Physics. 95th Edition. CRC Press LLC, Boca Raton: FL 2014-2015, p. 3-4
- ILO-WHO International Chemical Safety Cards (ICSCs): Ethanal — solubilityILO-WHO International Chemical Safety Cards (ICSCs)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/177#section=Solubility. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred.
- 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.