Crotonaldehyde
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-Crotonaldehyde_3D_ball.png) | |
| Names | |
|---|---|
| IUPAC name
(2E)-but-2-enal | |
| Other names
Crotonaldehyde Crotoinic aldehyde β-Methacrolein β-Methyl acrolein 2-butenal Propylene aldehyde | |
| Identifiers | |
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| 3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.021.846 |
| EC Number | 204-647-1 |
| KEGG | |
| PubChem CID |
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| UNII |
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| 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] |
| Refractive index (nD) |
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| R-phrases (outdated) | R11 R24/25 R26 R37/38 R41 R48/22 R50 R68 |
| S-phrases (outdated) | S26 S28 S36/37/39 S45 S61 |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 | |
| 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): | |
| LC50 (median concentration) |
600 ppm (rat, 30 min) 1375 ppm (rat, 30 min) 519 ppm (mouse, 2 hr) 1500 ppm (rat, 30 min)[3] |
| LCLo (lowest published) |
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 |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
 verify (what is  ?) | |
| 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 affords 3-penten-2-ol.[6]
Rxn of Crotonaldehyde with ethanol then gives Kethoxal (anhydrous).
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
- ↑ Merck Index, 11th Edition, 2599
- 1 2 3 4 5 "NIOSH Pocket Guide to Chemical Hazards #0157". National Institute for Occupational Safety and Health (NIOSH).
- 1 2 "Crotonaldehyde". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH).
- 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
- ↑ Longley, Jr., R. I..; Emerson, W. S.; Blardinelli, A. J. (1963). "3,4-Dihydro-2-methoxy-4-methyl-2H-pyran". Org. Synth.; Coll. Vol., 4, p. 311
- ↑ Coburn, E. R. (1955). "3-Penten-2-ol". Org. Synth.; Coll. Vol., 3, p. 696