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Structural formula Ball-and-stick model
CAS number 107-20-0 YesY, (hydrate: 34789-09-8, 7737-02-2)
PubChem 33
ChemSpider 32 YesY
EC number 203-472-8
Jmol-3D images Image 1
Molecular formula C2H3ClO
Molar mass 78.50 g mol-1
Appearance Colourless liquid
Odor accrid, penetrating
Density 1.117 g/mL
Melting point −16.3 °C (2.7 °F; 256.8 K)
Boiling point 85–85.5 °C
Solubility in water soluble
Solubility soluble in acetone, methanol
Main hazards alkylating agent
Flash point 87.7 °C (189.9 °F) (closed cup)
Related compounds
Related compounds 2-chloroethanol, Chloroacetic acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Chloroacetaldehyde is the organic compound with the formula ClCH2CHO. Like some related compounds, it is highly electrophilic reagent and a potentially dangerous alkylating agent. The compound is not normally encountered in the anhydrous form, but rather as the hydrate (acetal), ClCH2CH(OH)2. Chloroacetaldehyde is a useful intermediate in the synthesis, e.g. of 2-aminothiazole or many pharmaceutical compounds. Another use is to facilitate bark removal from tree trunks.

Synthesis and reactions[edit]

The hydrate of chloroacetaldehyde is produced by the oxidation of aqueous vinyl chloride using chlorine:

ClCH=CH2 + Cl2 + H2O → ClCH2CHO + 2 HCl

It can also be prepared from vinyl acetate.[1]

Being bifunctional, chloroacetaldehyde is a versatile precursor to many heterocyclic compounds. It condenses with thiourea derivatives to give aminothiazoles. This reaction was once important as a precursor to sulfathiazole, one of the first sulfa drugs.[1]

Environmental aspects[edit]

Chloroacetaldehyde is a metabolite in the degradation of 1,2-dichloroethane, which initially converts to chloroethanol. This metabolic pathway is topical since billions of kilograms of 1,2-dichloroethane have been produced as a precursor to vinyl chloride.[2]


Based on data collected from human studies in 1962, exposures to 45 ppm of chloroacetaldehyde were found to be very disagreeable and caused conjunctival irritation to the subjects.[3] The Occupational Safety and Health Administration established a permissible exposure limit at a ceiling of 1 ppm (3 mg/m3) for exposures to chloroacetaldehyde.[4]


  1. ^ a b Reinhard Jira, Erwin Kopp, Blaine C. McKusick, Gerhard Röderer, Axel Bosch, Gerald Fleischmann “Chloroacetaldehydes“ in Ullmann's Encyclopedia of Industrial Chemistry, 2007, Wiley-VCH, Weinheim. doi:10.1002/14356007.a06_527.pub2
  2. ^ Janssen, D. B.; van der Ploeg, J. R. and Pries, F., "Genetics and biochemistry of 1,2-dichloroethane degradation", Biodegradation, 1994, 5, 249-57.doi:10.1007/BF00696463
  3. ^ Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)
  4. ^ CDC - NIOSH Pocket Guide to Chemical Hazards