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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]
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Names | |
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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 | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard | 100.021.846 |
EC Number |
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KEGG | |
PubChem CID |
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RTECS number |
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UNII |
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UN number | 1143 |
CompTox Dashboard (EPA) |
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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] |
Refractive index (nD) |
1.4362 |
Hazards | |
GHS labelling: | |
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Danger | |
H225, H301, H310, H311, H315, H318, H330, H335, H341, H373, H400 | |
P201, P202, P210, P233, P240, P241, P242, P243, P260, P261, P262, P264, P270, P271, P273, P280, P281, P284, P301+P310, P302+P350, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P308+P313, P310, P312, P314, P320, P321, P322, P330, P332+P313, P361, P362, P363, P370+P378, P391, P403+P233, P403+P235, P405, P501 | |
NFPA 704 (fire diamond) | |
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] |
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 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Crotonaldehyde is produced by the aldol condensation of acetaldehyde:
Crotonaldehyde is a multifunctional molecule that exhibits diverse reactivity. It is a prochiral dienophile.[5] It is a Michael acceptor. Addition of methylmagnesium chloride produces 3-penten-2-ol.[6]
Polyurethane catalyst N,N,N′,N′-tetramethyl-1,4-butanediamine (also known as NIAX TMBDA) was obtained by hydrogenating the reaction product of crotonaldehyde and dimethylamine.[7]
It is a precursor to many fine chemicals. A prominent industrial example is the crossed aldol condensation with diethyl ketone to give trimethylcyclohexenone, this can be easily converted to trimethylhydroquinone, which is a precursor to the vitamin E.[9] Other derivatives include crotonic acid, 3-methoxybutanol and the food preservative Sorbic acid. Condensation with two equivalents of urea gives a pyrimidine derivative that is employed as a controlled-release fertilizer. [4]
Crotonaldehyde is a potent irritant even at the ppm levels. It is not very toxic, with an LD50 of 174 mg/kg (rats, oral).[4]