Acetaldehyde



Acetaldehyde
IUPAC name acetaldehyde
Systematic name ethanal
Identifiers
CAS number 75-07-0
EINECS number 200-836-8
RTECS number AB1925000
SMILES CC=O
Properties
Molecular formula C2H4O
Molar mass 44.05 g mol−1
Appearance Colorless liquid
Pungent, fruity odor
Density 0.788 g cm−3
Melting point

−123.5 °C

Boiling point

20.2 °C

Solubility in water soluble in all proportions
Viscosity ~0.215 at 20 °C
Structure
Molecular shape trigonal planar (sp²) at C1
tetrahedral (sp³) at C2
Dipole moment 2.7 D
Hazards
MSDS External MSDS
EU classification Very flammable (F+)
Harmful (Xn)
Carc. Cat. 3
NFPA 704
4
2
0
 
R-phrases R12, R36/37, R40
S-phrases S36/37
Flash point −39 °C
Autoignition
temperature 		185 °C
Related Compounds
Related aldehydes Ethylene oxide
Supplementary data page
Structure and
properties 		εr, etc.
Thermodynamic
data 		Phase behaviour
Solid, liquid, gas
Spectral data MS
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Acetaldehyde, sometimes known as ethanal, is an metabolism. It is popularly known as the chemical that causes hangovers.[1]

In the chemical industry, acetaldehyde is used as an intermediate in the production of Wacker process.

Biological aspects

In the liver, the yeast involve the conversion of pyruvate into acetaldehyde by the enzyme pyruvate decarboxylase, followed by the conversion of acetaldehyde into ethanol. The latter reaction is again catalyzed by an alcohol dehydrogenase, now operating in the opposite direction.

Acetaldehyde and hangovers

Most people of East Asian descent have a disulfiram (Antabuse) also prevents the oxidation of acetaldehyde to acetic acid, with the same unpleasant effects for drinkers. It is used in the treatment of alcoholism.

Applications in organic synthesis

Acetaldehyde is a common 2-carbon building block in formaldehyde add to MeCHO to give pentaerythritol, C(CH2OH)4.[6]

In a amino acid alanine.[7] Acetaldehyde can condense with amines to yield imines, such as the condensation with cyclohexylamine to give N-ethylidenecyclohexylamine. These imines can be used to direct subsequent reactions like an aldol condensation.[8]

It is also an important building block for the synthesis of ammonia to 5-ethyl-2-methylpyridine ("aldehyde-collidine”).[9]

Acetal derivatives

Three molecules of acetaldehyde condense to form “metaldehyde.

Acetaldehyde forms a stable acetal is used more widely to describe other compounds with the formula RCH(OR')2.

Ethenol

Only a trace of acetaldehyde exists as the ethenol, with Keq = 6 x 10-5.[11]

Environmental occurrence

Acetaldehyde is an plastics processing industry. [12]

Safety

Acetaldehyde is toxic, an irritant, and a probable carcinogen.[13]

References

  1. ^ How Hangovers Work, HowStuffWorks
  2. ^ Xiao Q, Weiner H, Crabb DW (1996). "The mutation in the mitochondrial aldehyde dehydrogenase (ALDH2) gene responsible for alcohol-induced flushing increases turnover of the enzyme tetramers in a dominant fashion". J. Clin. Invest. 98 (9): 2027-32. PMID 8903321.
  3. ^ Sowin, T. J.; Melcher, L. M. ”Acetaldehyde” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289
  4. ^ Behrens, C.; Paquette, L. A. (2004). "N-Benzyl-2,3-Azetidinedione". Org. Synth.; Coll. Vol. 10: 41. 
  5. ^ Walter, L. A. (1955). "1-(α-Pyridyl)-2-Propanol". Org. Synth.; Coll. Vol. 3: 757. 
  6. ^ Schurink, H. B. J. (1941). "Pentaerythritol". Org. Synth.; Coll. Vol. 1: 425. 
  7. ^ Kendall, E. C. McKenzie, B. F. (1941). "dl-Alanine". Org. Synth.; Coll. Vol. 1: 21. 
  8. ^ Org. Synth.; Coll. Vol. 6: 901. 
  9. ^ Frank, R. L.; Pilgrim, F. J.; Riener, E. F. (1963). "5-Ethyl-2-Methylpyridine". Org. Synth.; Coll. Vol. 4: 451. 
  10. ^ Adkins, H.; Nissen, B. H. (1941). "Acetal". Org. Synth.; Coll. Vol. 1: 1. 
  11. ^ March, J. “Organic Chemistry: Reactions, Mechanisms, and Structures” J. Wiley, New York: 1992. ISBN 0-471-58148-8.
  12. ^ Smoking. (2006). Encyclopædia Britannica. Accessed 27 Oct 2006.
  13. ^ Chemical Summary For Acetaldehyde, US Environmental Protection Agency

See also

  • Wine faultbe-x-old:Ацэтальдэгід
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Acetaldehyde". A list of authors is available in Wikipedia.