Acetaldehyde

Acetaldehyde

Names
Preferred IUPAC name Acetaldehyde
Systematic IUPAC name Ethanal
Other names Acetic aldehyde Ethyl aldehyde Acetylaldehyde
Identifiers
CAS Number	75-07-0 Y
3D model (Jmol)	Interactive image Interactive image
ChEBI	CHEBI:15343 Y
ChEMBL	ChEMBL170365 Y
ChemSpider	172 Y
ECHA InfoCard	100.000.761
EC Number	200-836-8
IUPHAR/BPS	6277
KEGG	C00084 Y
PubChem	177
RTECS number	AB1925000
UNII	GO1N1ZPR3B Y
InChI InChI=1S/C2H4O/c1-2-3/h2H,1H3 Y Key: IKHGUXGNUITLKF-UHFFFAOYSA-N Y InChI=1/C2H4O/c1-2-3/h2H,1H3 Key: IKHGUXGNUITLKF-UHFFFAOYAB
SMILES O=CC CC=O
Properties
Chemical formula	C2H4O
Molar mass	44.05 g·mol−1
Appearance	Colourless liquid
Odor	Etherial
Density	0.784 g·cm−3 (20 °C) 0.7904–0.7928 g·cm−3 (10 °C)
Melting point	−123.37 °C (−190.07 °F; 149.78 K)
Boiling point	20.2 °C (68.4 °F; 293.3 K)
Solubility in water	miscible
Solubility	miscible with ethanol, ether, benzene, toluene, xylene, turpentine, acetone slightly soluble in chloroform
log P	-0.34
Vapor pressure	740 mmHg (20 °C)
Acidity (pKa)	13.57
Magnetic susceptibility (χ)	-.5153−6 cm3/g
Refractive index (nD)	1.3316
Viscosity	~0.215 at 20 °C
Structure
Molecular shape	trigonal planar (sp²) at C1 tetrahedral (sp³) at C2
Dipole moment	2.7 D
Thermochemistry
Std molar entropy (So298)	250 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−166 kJ·mol−1
Hazards
Main hazards	potential occupational carcinogen
Safety data sheet	See: data page HMDB
GHS pictograms
GHS hazard statements	H224, H319, H335, H351
GHS precautionary statements	P210, P261, P281, P305+351+338
EU classification (DSD)	F+ Xn Carc. Cat. 3
R-phrases	R12 R36/37 R40
S-phrases	(S2) S16 S33 S36/37
NFPA 704	4 2 2
Flash point	−39.00 °C; −38.20 °F; 234.15 K
Autoignition temperature	175.00 °C; 347.00 °F; 448.15 K
Explosive limits	4.0–60%
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1930 mg/kg (rat, oral)
LC50 (median concentration)	13,000 ppm (rat), 17,000 ppm (hamster), 20,000 ppm (rat)
US health exposure limits (NIOSH):
PEL (Permissible)	200 ppm (360 mg/m3)
IDLH (Immediate danger)	2000 ppm
Related compounds
Related aldehydes	Formaldehyde Propionaldehyde
Related compounds	Ethylene oxide
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

0.7904–0.7928 g·cm⁻³ (10 °C)

Acetaldehyde (systematic name ethanal) is an organic chemical compound with the formula CH₃CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale in industry. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants. It is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase and may be a contributing factor to hangovers from alcohol consumption. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke. Consumption of disulfiram inhibits acetaldehyde dehydrogenase, the enzyme responsible for the metabolism of acetaldehyde, thereby causing it to build up in the body.

The International Agency for Research on Cancer (IARC) has listed acetaldehyde as a Group 1 carcinogen. Acetaldehyde is "one of the most frequently found air toxins with cancer risk greater than one in a million."

Acetaldehyde was first observed by the Swedish pharmacist/chemist Carl Wilhelm Scheele (1774); it was then investigated by the French chemists Antoine François, comte de Fourcroy and Louis Nicolas Vauquelin (1800), and the German chemists Johann Wolfgang Döbereiner (1821, 1822, 1832) and Justus von Liebig (1835). In 1835, Liebig named it "aldehyde"; the name was later altered to "acetaldehyde".