Chloroacetaldehyde

Chloroacetaldehyde
IUPAC name Chloroacetaldehyde
Systematic name Chloroethanal
Identifiers
CAS number	107-20-0 Y, (hydrate: 34789-09-8, 7737-02-2)
PubChem	33
ChemSpider	32 Y
UNII	CF069F5D9C Y
EC number	203-472-8
Jmol-3D images	Image 1
SMILES C(C=O)Cl
InChI InChI=1S/C2H3ClO/c3-1-2-4/h2H,1H2 Key: QSKPIOLLBIHNAC-UHFFFAOYSA-N
Properties
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
Hazards
Main hazards	alkylating agent
Flash point	87.7 °C (189.9 °F) (closed cup)
Related compounds
Related compounds	2-chloroethanol, Chloroacetic acid
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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

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

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]

Safety

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]

References