Ethylene glycol vs Propylene glycol: what is the difference?
The body turns ethylene glycol into oxalic acid, which harms the kidneys, and propylene glycol into lactic acid, which it handles routinely.
One methyl group apart.
Sources and notes
- The sentence under the titlefrom sourceMoleculeFinder comparison notesThe pair's answer line.
- The two drawingscomputedMoleculeFinder rule (RDKit MCS)Drawn the same way round on the skeleton they share; the amber marks where the two differ.
- The captionfrom sourceMoleculeFinder curated
- What is highlightedfrom sourceMoleculeFinder curatedOne line under each drawing, written from the atoms the amber marks.
Side by side
| Ethylene glycol | Propylene glycol | |
|---|---|---|
| Molecular weightCalculated PubChem | 62.07 g/molC2H6O2 | 76.09 g/molC3H8O2 |
| Hydrogen-bond donorsCalculated PubChem | 2 | 2 |
| Where each turns upEditorial MoleculeFinder food and product lists | Not on our lists |
|
| FamilyEditorial MoleculeFinder curated | Alcohols | Alcohols |
| Everyday groupEditorial MoleculeFinder curated | Everyday chemistry | Food & flavor |
| Chemical groupsCalculated Found by rule (RDKit) | Alcohols | Alcohols |
| Hazard labelReported ECHA, EU CLP Regulation, Safe Work Australia via PubChem | Warning | Not recorded |
| The supplier-filed hazard label's signal word, not a statement about ordinary use. | ||
| Oral LD50Measured HSDB via PubChem | 4,700 mg/kgpure ethylene glycol, rat, oral | 22,000 mg/kgpure propylene glycol, 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 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 174 (Ethylene glycol) and 1030 (Propylene glycol).
In more detail
The difference is toxicological rather than chemical. Ethylene glycol is C2H6O2 and the body oxidises it to oxalic acid, which forms calcium oxalate crystals in the kidneys, and that is what makes antifreeze poisoning so damaging. Propylene glycol is C3H8O2 and is metabolised to lactic acid, which the body handles routinely, which is why it is permitted in food, e-liquid, and medicines. Both are sweet tasting, and the sweetness of ethylene glycol is a recurring hazard to pets and children. Many antifreeze products now use propylene glycol for exactly that reason, and some add a bitterant to the ethylene glycol kind.
Sources and notes
- The paragraphfrom sourceMoleculeFinder comparison notes
Questions
- What is the difference between Ethylene glycol and Propylene glycol?
- The body turns ethylene glycol into oxalic acid, which harms the kidneys, and propylene glycol into lactic acid, which it handles routinely.
- Is Ethylene glycol bigger than Propylene glycol?
- Propylene glycol is the heavier molecule, 76.09 g/mol against 62.07 g/mol for Ethylene glycol. Ethylene glycol is C2H6O2 and Propylene glycol is C3H8O2.
- Which has the lower reported LD50, Ethylene glycol or Propylene glycol?
- Ethylene glycol, at 4,700 mg/kg (oral, rat), against 22,000 mg/kg (oral, rat) for Propylene glycol. 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.