|Jmol-3D images||Image 1
|Molar mass||56.06 g mol−1|
|Appearance||Colorless to yellow liquid|
−88 °C, 185 K, -126 °F
53 °C, 326 K, 127 °F
|Solubility in water||very soluble|
|MSDS||JT Baker MSDS|
|Main hazards||Highly poisonous. Causes severe irritation to exposed membranes. Extremely flammable liquid and vapor.|
|Flash point||−26 °C (−15 °F)|
|278 °C (532 °F)|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Acrolein (systematic name: propenal) is the simplest unsaturated aldehyde. It is a colourless liquid with a piercing, disagreeable, acrid smell. The smell of burnt fat (as when cooking oil is heated to its smoke point) is caused by glycerol in the burning fat breaking down into acrolein. It is produced industrially from propylene and mainly used as a biocide and a building block to other chemical compounds, such as the amino acid methionine.
- CH2=CHCH3 + O2 → CH2=CHCHO + H2O
About 500,000 tons of acrolein are produced in this way annually in North America, Europe, and Japan. Additionally, all acrylic acid is produced via the transient formation of acrolein. The main challenge is in fact the competing over oxidation to this acid. Propane represents a promising but challenging feedstock for the synthesis of acrolein (and acrylic acid).
When glycerol (also called glycerin) is heated to 280 °C, it decomposes into acrolein. This route is attractive when glycerol is cogenerated in the production of biodiesel from fatty acids. The dehydration of glycerol has been demonstrated but has not proven competitive with the route from petrochemicals.
Niche or laboratory methods
The original industrial route to acrolein, developed by Degussa, involves condensation of formaldehyde and acetaldehyde. Acrolein may also be produced on lab scale by the reaction of potassium bisulfate on glycerol (glycerine).
Acrolein is a relatively electrophilic compound and a reactive one, hence its high toxicity. It is a good Michael acceptor, hence its useful reaction with thiols. It forms acetals readily, a prominent one being the spirocycle derived from pentaerythritol, diallylidene pentaerythritol. Acrolein participates in many Diels-Alder reactions, even with itself. Via Diels-Alder reactions, it is a precursor to some commercial fragrances, including lyral, norbornene-2-carboxaldehyde, and myrac aldehyde.
Acrolein is mainly used as a contact herbicide to control submersed and floating weeds, as well as algae, in irrigation canals. It is used at a level of 10 ppm in irrigation and recirculating waters. In the oil and gas industry, it is used as a biocide in drilling waters, as well as a scavenger for hydrogen sulfide and mercaptans.
A number of useful compounds are made from acrolein, exploiting its bifunctionality. The amino acid methionine is produced by addition of methanethiol followed by the Strecker synthesis. Acrolein condenses with acetaldehyde and amines to give methylpyridines. It is also thought to be an intermediate in the Skraup synthesis of quinolines, but is rarely used as such due to its instability.
Acrolein will polymerize in the presence of oxygen and in water at concentrations above 22%. The color and texture of the polymer depends on the conditions. Over time, it will polymerize with itself to form a clear, yellow solid. In water, it will form a hard, porous plastic.
Acrolein is toxic and is a strong irritant for the skin, eyes, and nasal passages. The main metabolic pathway for acrolein is the alkylation of glutathione. The WHO suggests a "tolerable oral acrolein intake" of 7.5 μg/day per kilogram of body weight. Although acrolein occurs in French fries, the levels are only a few micrograms per kilogram.
Connections exist between acrolein in the smoke from tobacco cigarettes and the risk of lung cancer. In terms of the "noncarcinogenic health quotient" for components in cigarette smoke, acrolein dominates, contributing 40 times more than the next component, hydrogen cyanide.
The "acrolein test" is for the presence of glycerin or fats. A sample is heated with potassium bisulfate, and acrolein is released if the test is positive. When a fat is heated strongly in the presence of a dehydrating agent such as potassium bisulfate (KHSO4), the glycerol portion of the molecule is dehydrated to form the unsaturated aldehyde, acrolein (CH2=CH–CHO), which has the odor peculiar to burnt cooking grease. More modern methods exist.
- Dietrich Arntz, Achim Fischer, Mathias Höpp, Sylvia Jacobi, Jörg Sauer, Takashi Ohara, Takahisa Sato, Noboru Shimizu and Helmut Schwind "Acrolein and Methacrolein" in Ullmann's Encyclopedia of Industrial Chemistry, 2012, Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_149.pub2
- Andreas Martin, Udo Armbruster, Hanan Atia "Recent developments in dehydration of glycerol toward acrolein over heteropolyacids" European Journal of Lipid Science and Technology 2012, Volume 114, pages 10–23. doi:10.1002/ejlt.201100047
- Homer Adkins and W. H. Hartung (1941), "Acrolein", Org. Synth.; Coll. Vol. 1: 15
- M J Dykstra, L E Reuss (2003) Biological Electron Microscopy: Theory, Techniques, and Troubleshooting. Springer, ISBN 0-306-47749-1, ISBN 978-0-306-47749-2.
- Klaus Abraham, Susanne Andres, Richard Palavinskas, Katharina Berg, Klaus E. Appel, Alfonso Lampen "Toxicology and risk assessment of acrolein in food" Mol. Nutr. Food Res. 2011, vol. 55, pp. 1277–1290. doi:10.1002/mnfr.201100481
- Feng, Z; Hu W, Hu Y, Tang M (October 2006). "Acrolein is a major cigarette-related lung cancer agent: Preferential binding at p53 mutational hotspots and inhibition of DNA repair". Proceedings of the National Academy of Sciences 103 (42): 15404–15409. Bibcode:2006PNAS..10315404F. doi:10.1073/pnas.0607031103. PMC 1592536. PMID 17030796.
- Hans-Juergen Haussmann, "Use of Hazard Indices for a Theoretical Evaluation of Cigarette Smoke Composition" Chem. Res. Toxicol., 2012, vol. 25, pp 794–810. doi:10.1021/tx200536w
- Appendix A To Part 136 Methods For Organic Chemical Analysis of Municipal and Industrial Wastewater, Method 603—Acrolein And Acrylonitrile>