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Structural formula
Ball-and-stick model
Preferred IUPAC name
Systematic IUPAC name
Other names
3D model (JSmol)
ECHA InfoCard 100.003.158
EC Number 203-472-8
Molar mass 78.50 g mol−1
Appearance Colourless liquid
Odor acrid, penetrating
Density 1.117 g/mL
Melting point −16.3 °C (2.7 °F; 256.8 K)
Boiling point 85 to 85.5 °C (185.0 to 185.9 °F; 358.1 to 358.6 K)
Solubility soluble in acetone, methanol
Main hazards alkylating agent
Flash point 87.7 °C (189.9 °F) (closed cup)
Lethal dose or concentration (LD, LC):
89 mg/kg (oral, rat)
82 mg/kg (oral, mouse)[2]
200 ppm (rat, 1 hr)[3]
US health exposure limits (NIOSH):
PEL (Permissible)
C 1 ppm (3 mg/m3)[1]
REL (Recommended)
C 1 ppm (3 mg/m3)[1]
IDLH (Immediate danger)
45 ppm[1]
Related compounds
Related compounds
2-chloroethanol, Chloroacetic acid
Except where otherwise noted, 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 chlorination of aqueous vinyl chloride:

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

It can also be prepared from vinyl acetate.[4] The related bromoacetaldehyde is prepared via bromination of vinyl acetate. It also rapidly forms an acetals in the presence of alcohols.[5]

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.[4]

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.[6]


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.[7] The Occupational Safety and Health Administration established a permissible exposure limit at a ceiling of 1 ppm (3 mg/m3) for exposures to chloroacetaldehyde.[8]


  1. ^ a b c "NIOSH Pocket Guide to Chemical Hazards #0118". National Institute for Occupational Safety and Health (NIOSH). 
  2. ^ "Chloroacetaldehyde". National Institute for Occupational Safety and Health. 4 December 2014. Retrieved 20 February 2015. 
  3. ^ "Chloroacetaldehyde". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH). 
  4. ^ 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
  5. ^ S. M. McElvain and D. Kundiger "Bromoacetal" Organic Syntheses 1943, volume 23, p. 8. doi:10.15227/orgsyn.023.0008.
  6. ^ 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
  7. ^ Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)
  8. ^ CDC - NIOSH Pocket Guide to Chemical Hazards