Crotonaldehyde

Crotonaldehyde is a chemical compound with the formula CH3CH=CHCHO. The compound is usually sold as a mixture of the E- and Z-isomers, which differ with respect to the relative position of the methyl and formyl groups. The E-isomer is more common (data given in Table is for the E-isomer). This lachrymatory liquid is moderately soluble in water and miscible in organic solvents. As an unsaturated aldehyde, crotonaldehyde is a versatile intermediate in organic synthesis. It occurs in a variety of foodstuffs, e.g. soybean oils.[4]

Crotonaldehyde[1]
Names
IUPAC name
(2E)-but-2-enal
Other names
Crotonaldehyde
Crotoinic aldehyde
β-Methacrolein
β-Methyl acrolein
2-butenal
Propylene aldehyde
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.021.846
EC Number
  • 204-647-1
KEGG
UNII
Properties
C4H6O
Molar mass 70.091 g·mol−1
Appearance colourless liquid
Odor pungent, suffocating odor
Density 0.846 g/cm3
Melting point −76.5 °C (−105.7 °F; 196.7 K)
Boiling point 104.0 °C (219.2 °F; 377.1 K)
18% (20°C)[2]
Solubility very soluble in ethanol, ethyl ether, acetone
soluble in chloroform
miscible in benzene
Vapor pressure 19 mmHg (20°C)[2]
1.4362
Hazards
R-phrases (outdated) R11 R24/25 R26 R37/38 R41 R48/22 R50 R68
S-phrases (outdated) S26 S28 S36/37/39 S45 S61
NFPA 704 (fire diamond)
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
3
4
2
Flash point 13 °C (55 °F; 286 K)
207 °C (405 °F; 480 K)
Explosive limits 2.1-15.5%
Lethal dose or concentration (LD, LC):
600 ppm (rat, 30 min)
1375 ppm (rat, 30 min)
519 ppm (mouse, 2 hr)
1500 ppm (rat, 30 min)[3]
400 ppm (rat, 1 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 2 ppm (6 mg/m3)[2]
REL (Recommended)
 TWA 2 ppm (6 mg/m3)[2]
IDLH (Immediate danger)
 50 ppm[2]
Related compounds
Related alkenals
 Acrolein

cis-3-hexenal
(E,E)-2,4-Decadienal

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Production and uses

Crotonaldehyde is produced by the aldol condensation of acetaldehyde:

2 CH3CHO → CH3CH=CHCHO + H2O

Its main application is as a precursor to fine chemicals. Sorbic acid, a food preservative, and trimethylhydroquinone, a precursor to the vitamin E, are prepared from crotonaldehyde. Other derivatives include crotonic acid and 3-methoxybutanol.[4]

Crotonaldehyde is a multifunctional molecule that exhibits diverse reactivity. It is an excellent prochiral dienophile.[5] It is a Michael acceptor. Addition of methylmagnesium chloride produces 3-penten-2-ol.[6]

The reaction of crotonaldehyde with ethanol then gives kethoxal (anhydrous).

Polyurethane catalyst N,N,N',N'-tetramethyl-1,4-butanediamine (also known as TMBDA) is obtained by hydrogenating N,N,N',N'-tetramethyl-1,4-butenediamine which is a reaction product of crotonaldehyde and dimethylamine.[7]

Safety

Crotonaldehyde is an irritant. It is listed as an "extremely hazardous substance" as defined by the U.S. Emergency Planning and Community Right-to-Know Act. It occurs widely in nature. It is used to make preservatives.

See also

References
  1. Merck Index, 11th Edition, 2599
  2. NIOSH Pocket Guide to Chemical Hazards. "#0157". National Institute for Occupational Safety and Health (NIOSH).
  3. "Crotonaldehyde". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. R. P. Schulz, J. Blumenstein, C. Kohlpaintner (2005). "Crotonaldehyde and Crotonic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_083.CS1 maint: uses authors parameter (link)
  5. Longley, Jr., R. I..; Emerson, W. S.; Blardinelli, A. J. (1963). "3,4-Dihydro-2-methoxy-4-methyl-2H-pyran". Organic Syntheses.CS1 maint: multiple names: authors list (link); Collective Volume, 4, p. 311
  6. Coburn, E. R. (1955). "3-Penten-2-ol". Organic Syntheses.; Collective Volume, 3, p. 696
  7. https://jadedman.wordpress.com/2011/01/08/catalysts/
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