Formaldehyde vs Acetaldehyde: what is the difference?
Formaldehyde is the simplest aldehyde, used in resins and embalming; acetaldehyde is what ethanol becomes in the body, long blamed for part of a hangover.
Sources and notes
- The sentence under the titlefrom sourceMoleculeFinder comparison notesThe pair's answer line.
- The two drawingscomputedMoleculeFinder rule (RDKit MCS)Each molecule's own drawing, as its page shows it. The common core, 2 of 3 atoms, is too small to align on.
Side by side
| Formaldehyde | Acetaldehyde | |
|---|---|---|
| Molecular weightCalculated PubChem | 30.03 g/molCH2O | 44.05 g/molC2H4O |
| Hydrogen-bond donorsCalculated PubChem | 0 | 0 |
| Where each turns upEditorial MoleculeFinder food and product lists | Not on our lists | |
| FamilyEditorial MoleculeFinder curated | Aldehydes | Aldehydes |
| Everyday groupEditorial MoleculeFinder curated | Everyday chemistry | Food & flavor |
| Chemical groupsCalculated Found by rule (RDKit) | Aldehydes | Aldehydes |
| Hazard labelReported ECHA, EU CLP Regulation, Safe Work Australia, HSDB via PubChem | Danger | Danger |
| The supplier-filed hazard label's signal word, not a statement about ordinary use. | ||
| Oral LD50Measured HSDB via PubChem | 100 mg/kgpure formaldehyde, rat, oral | 661 mg/kgpure acetaldehyde, rat, oral |
| A single acute animal measure. It ranks nothing about human safety. | ||
Sources and notes
- Molecular weightcomputedPubChemComputed from the structure; the formula is under each weight.
- Hydrogen-bond donorscomputedPubChemThe hydrogens on nitrogen or oxygen that each molecule can lend to a hydrogen bond, counted from its structure.
- Where each turns upfrom sourceMoleculeFinder food and product listsEach amount is an editorial figure from our lists, not a measurement of any one product. Each mark is set by hand on the list, never inferred.
- Familyfrom sourceMoleculeFinder curated
- Everyday groupfrom sourceMoleculeFinder curated
- Chemical groupscomputedFound by rule (RDKit)Each group is found in the structure by a chemical pattern.
- Hazard labelfrom sourceECHA, EU CLP Regulation, Safe Work Australia, HSDB via PubChem
- Oral LD50from sourceHSDB via PubChem
- ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
- EU CLP Regulationfrom sourceAttributionSource: EUR-Lex, Regulation (EC) No 1272/2008, © European Union.
- Safe Work Australiafrom sourceAttributionSource: Safe Work Australia, Hazardous Chemical Information System, © Commonwealth of Australia, CC BY 4.0.
- Identifiersfrom sourcePubChemPubChem CID 712 (Formaldehyde) and 177 (Acetaldehyde).
In more detail
Both are small aldehydes, both are reactive, and both are classified as carcinogenic to humans, but they arrive by different routes. Formaldehyde is the simplest of all aldehydes at 30.03, used in resins, embalming fluid and disinfectants, and it cross-links proteins on contact, which is precisely what preservation and what irritation both are. Acetaldehyde at 44.05 is what ethanol becomes as the body breaks it down; it is long blamed for part of a hangover, and it causes the flushing reaction in people whose version of the clearing enzyme works slowly. Their reported oral LD50 values differ by more than sixfold, 100 mg/kg in rats for formaldehyde against 661 mg/kg for acetaldehyde. The body produces both in small amounts as a normal part of metabolism.
Sources and notes
- The paragraphfrom sourceMoleculeFinder comparison notes
Questions
- What is the difference between Formaldehyde and Acetaldehyde?
- Formaldehyde is the simplest aldehyde, used in resins and embalming; acetaldehyde is what ethanol becomes in the body, long blamed for part of a hangover.
- Is Formaldehyde bigger than Acetaldehyde?
- Acetaldehyde is the heavier molecule, 44.05 g/mol against 30.03 g/mol for Formaldehyde. Formaldehyde is CH2O and Acetaldehyde is C2H4O.
- Which has the lower reported LD50, Formaldehyde or Acetaldehyde?
- Formaldehyde, at 100 mg/kg (oral, rat), against 661 mg/kg (oral, rat) for Acetaldehyde. An LD50 is one acute animal measurement, and the two here were not necessarily measured in the same species, so it is a data point rather than a ranking of how dangerous either is to a person.
Sources and notes
- The answersfrom sourceMoleculeFinderThe first is the pair's answer line; the others are read off the table above.