Crotonaldehyde

Crotonaldehyde[1]
Skeletal formula of crotonaldehyde
Ball-and-stick model of (Z)-crotonaldehyde
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 70.09 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R-phrases (outdated) R11 R24/25 R26 R37/38 R41 R48/22 R50 R68
S-phrases (outdated) S26 S28 S36/37/39 S45 S61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
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., phosphorusSpecial hazards (white): no codeNFPA 704 four-colored diamond
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]
US health exposure limits (NIOSH):
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).
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Infobox references

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]

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. 1 2 3 4 5 "NIOSH Pocket Guide to Chemical Hazards #0157". National Institute for Occupational Safety and Health (NIOSH).
  3. 1 2 "Crotonaldehyde". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. 1 2 R. P. Schulz, J. Blumenstein, C. Kohlpaintner "Crotonaldehyde and Crotonic Acid" Ullmann's Encyclopedia of Chemical Technology, Wiley-VCH, Weinheim: 2005. doi:10.1002/14356007.a08_083
  5. ↑ Longley, Jr., R. I..; Emerson, W. S.; Blardinelli, A. J. (1963). "3,4-Dihydro-2-methoxy-4-methyl-2H-pyran". Organic Syntheses. ; 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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