Acetaldehyde

Names
Preferred IUPAC name Acetaldehyde[3]
Systematic IUPAC name Ethanal[3]
Other names Acetic aldehyde Ethyl aldehyde[1] Acetylaldehyde[2]
Identifiers
CAS Number	75-07-0 Y
3D model (JSmol)	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 CID	177
RTECS number	AB1925000
UNII	GO1N1ZPR3B Y
CompTox Dashboard (EPA)	DTXSID5039224
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	44.053 g·mol−1
Appearance	Colourless gas or liquid
Odor	Ethereal
Density	0.784 g·cm−3 (20 °C)[4] 0.7904–0.7928 g·cm−3 (10 °C)[4]
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)[5]
Acidity (pKa)	13.57 (25 °C, H2O)[6]
Magnetic susceptibility (χ)	-.5153−6 cm3/g
Refractive index (nD)	1.3316
Viscosity	0.21 mPa-s at 20 °C (0.253 mPa-s at 9.5 °C)[7]
Structure
Molecular shape	trigonal planar (sp2) at C1 tetrahedral (sp3) at C2
Dipole moment	2.7 D
Thermochemistry[8]
Heat capacity (C)	89 J·mol−1·K−1
Std molar entropy (S⦵298)	160.2 J·mol−1·K−1
Std enthalpy of formation (ΔfH⦵298)	−192.2 kJ·mol−1
Gibbs free energy (ΔfG⦵)	-127.6 kJ·mol−1
Related compounds
Related aldehydes	Formaldehyde Propionaldehyde
Related compounds	Ethylene oxide
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	potential occupational carcinogen[10]
GHS labelling:
Pictograms	[9]
Hazard statements	H224, H319, H335, H351[9]
Precautionary statements	P210, P261, P281, P305+P351+P338[9]
NFPA 704 (fire diamond)	3 4 3
Flash point	−39.00 °C; −38.20 °F; 234.15 K
Autoignition temperature	175.00 °C; 347.00 °F; 448.15 K[5]
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)[10]
NIOSH (US health exposure limits):
PEL (Permissible)	200 ppm (360 mg/m3)[5]
IDLH (Immediate danger)	2000 ppm[5][10]
Safety data sheet (SDS)	HMDB
Supplementary data page
Acetaldehyde (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Y verify (what is YN ?) Infobox references

Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH₃ CHO, sometimes abbreviated as MeCHO. It is a colorless liquid or gas, boiling near room temperature. 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,^[11] and is produced by plants. It is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase and is a contributing cause of hangover after alcohol consumption. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke.^[12] 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.^[13] Acetaldehyde is "one of the most frequently found air toxins with cancer risk greater than one in a million".^[14]

History

Acetaldehyde was first observed by the Swedish pharmacist/chemist Carl Wilhelm Scheele (1774);^[15] it was then investigated by the French chemists Antoine François, comte de Fourcroy and Louis Nicolas Vauquelin (1800),^[16] and the German chemists Johann Wolfgang Döbereiner (1821, 1822, 1832)^[17] and Justus von Liebig (1835).^[18][19] In 1835, Liebig named it "aldehyde";^[20] the name was later altered to "acetaldehyde".^[21]

Production

In 2003, global production was about 1 million tonnes.^{[citation needed]} Before 1962, ethanol and acetylene were the major sources of acetaldehyde. Since then, ethylene is the dominant feedstock.^[22]

The main method of production is the oxidation of ethene by the Wacker process, which involves oxidation of ethene using a homogeneous palladium/copper catalyst system:

${\displaystyle {\ce {2 CH2=CH2 + O2 -> 2 CH3CHO}}}$

In the 1970s, the world capacity of the Wacker-Hoechst direct oxidation process exceeded 2 million tonnes annually.

Smaller quantities can be prepared by the partial oxidation of ethanol in an exothermic reaction. This process typically is conducted over a silver catalyst at about 500–650 °C.^[22]

${\displaystyle {\text{CH}}_3^{}{\text{CH}}_{}^{}}$Zdroj:https://en.wikipedia.org?pojem=Acetaldehyde
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