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paraldehyde

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paraldehyde

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Also known as Paral, paracetaldehyde, acetaldehyde trimer, paraacetaldehyde, 2,4,6-trimethyl-s-trioxane, 1,3,5-trimethyl-2,4,6-trioxane, 2,4,6-trimethyl-1,3,5-trioxane

Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane, with a methyl group substituted for a hydrogen atom at each carbon. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in ethanol. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of acetic acid. It attacks most plastics and rubbers and should be kept in glass bottles.

Chemical data

Formula
C6H12O3
Molecular weight
132.16 g/mol
IUPAC name
2,4,6-trimethyl-1,3,5-trioxane
SMILES
CC1OC(OC(O1)C)C
InChIKey
SQYNKIJPMDEDEG-UHFFFAOYSA-N
XLogP
0.7
Polar surface area
27.7 Ų
H-bond donors
0
H-bond acceptors
3
Formal charge
0

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Wikidata facts

Mass
132.078644
Show 8 more facts
melting point
12.6
chemical formula
C₆H₁₂O₃
Commons category
Paraldehyde
electric dipole moment
1.43
World Health Organisation international non-proprietary name
paraldehyde
canonical SMILES
CC1OC(OC(O1)C)C
isomeric SMILES
C[C@@H]1O[C@@H](OC(O1)C)C
boiling point
124.35
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Article

10 sections
Contents
  • Preparation
  • Stereochemistry
  • Reactions
  • Medical applications
  • As a hypnotic/sedative
  • As anti-seizure drug
  • Administration
  • Industrial applications
  • References
  • External links

Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane, with a methyl group substituted for a hydrogen atom at each carbon. The corresponding tetramer is metaldehyde. A colourless liquid, it is sparingly soluble in water and highly soluble in ethanol. Paraldehyde slowly oxidizes in air, turning brown and producing an odour of acetic acid. It attacks most plastics and rubbers and should be kept in glass bottles.

Paraldehyde was first observed in 1835 by the German chemist Justus Liebig; its empirical formula was determined in 1838 by Liebig's student Hermann Fehling. The German chemist Valentin Hermann Weidenbusch (1821–1893), another of Liebig's students, synthesized paraldehyde in 1848 by treating acetaldehyde with acid (either sulfuric or nitric acid) and cooling to 0°C. He found it quite remarkable that when paraldehyde was heated with a trace of the same acid, the reaction went the other way, recreating acetaldehyde.

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