Chloroacetaldehyde is an 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 hemiacetal (ClCH2CH(OH))2O.
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Names | |||
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Preferred IUPAC name
Chloroacetaldehyde | |||
Systematic IUPAC name
Chloroethanal | |||
Other names
2-Chloroacetaldehyde
2-Chloroethanal | |||
Identifiers | |||
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3D model (JSmol)
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ChEBI |
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ChemSpider |
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ECHA InfoCard | 100.003.158 | ||
EC Number |
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PubChem CID
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UNII |
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CompTox Dashboard (EPA)
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Properties | |||
C2H3ClO | |||
Molar mass | 78.50 g mol−1 | ||
Appearance | Colourless liquid | ||
Odor | acrid, penetrating[1] | ||
Density | 1.117 g/mL | ||
Melting point | −16.3 °C (2.7 °F; 256.8 K) hydrate melts at 43–50 °C[1] | ||
Boiling point | 85 to 85.5 °C (185.0 to 185.9 °F; 358.1 to 358.6 K) | ||
soluble[1] | |||
Solubility | organic solvents | ||
Hazards | |||
Occupational safety and health (OHS/OSH): | |||
Main hazards
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alkylating agent | ||
GHS labelling: | |||
Danger | |||
H301, H311, H314, H330, H351, H400 | |||
Flash point | 87.7 °C (189.9 °F) (closed cup) | ||
Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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89 mg/kg (oral, rat) 82 mg/kg (oral, mouse)[3] | ||
LC50 (median concentration)
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200 ppm (rat, 1 hr)[4] | ||
NIOSH (US health exposure limits): | |||
PEL (Permissible)
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C 1 ppm (3 mg/m3)[2] | ||
REL (Recommended)
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C 1 ppm (3 mg/m3)[2] | ||
IDLH (Immediate danger)
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45 ppm[2] | ||
Related compounds | |||
Related compounds
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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
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Chloroacetaldehyde is a metabolite of the antineoplastic ifosfamide and believed to be responsible for some of the toxicity observed with ifosfamide.
Hydrated chloroacetaldehyde is produced by the chlorination of aqueous vinyl chloride:
It can also be prepared from vinyl acetate[5] or by careful chlorination of acetaldehyde.[1] The related bromoacetaldehyde is prepared via bromination of vinyl acetate. It also rapidly forms an acetals in the presence of alcohols.[6]
Water free chloroacetaldehyde is prepared from the hydrate by azeotropic distillation with chloroform, toluene, or carbon tetrachloride. Anhydrous chloroacetaldehyde reversibly converts to polyacetals.[7][1] Less reactive chloroacetaldehyde derivatives might be used instead to obtain chloroacetaldehyde or bypass its intermediate formation completely: e.g. chloroacetaldehyde dimethyl acetal (2-chloro-1,1-dimethoxyethane) hydrolyzes in acidic conditions to give chloroacetaldehyde, which may then quickly react with the other reagents[7] instead of polymerizing.
Relevant to its occurrence in humans, it arises via the isomerization of chloroethylene oxide, a metabolite of vinyl chloride.[8]
Chloroacetaldehyde readily hydrates:
Being bifunctional, chloroacetaldehyde is a precursor to many heterocyclic compounds. It condenses with thiourea derivatives to give aminothiazoles. This reaction was once used in the preparation of sulfathiazole, one of the first sulfa drugs.[5] Chloroacetaldehyde is a building block in the synthesis of the pharmaceuticals altizide, polythiazide, brotizolam, and ciclotizolam.[7] Chloroacetaldehyde is an alkylating agent. It reacts with adenosine and cytidine to give cyclic products containing a fused imidazole group. This reaction is related to the possible mutagenic properties of chloroacetaldehyde.[9]
Chloroacetaldehyde is a metabolite in the degradation of 1,2-dichloroethane, which initially converts to chloroethanol. This metabolic pathway is topical because 1,2-dichloroethane is produced on a large scale as a precursor to vinyl chloride.[10]
Chloroacetaldehyde is corrosive to mucous membranes. It irritates eyes, skin and respiratory tract.[1]
Based on data collected from human studies in 1962, exposures to 45 ppm of chloroacetaldehyde were found to be disagreeable and caused conjunctival irritation to the subjects.[11] The Occupational Safety and Health Administration established a permissible exposure limit at a ceiling of 1 ppm (3 mg/m3) for exposures to chloroacetaldehyde.[12]
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