MOLECULE

Acrolein

Acrolein, also known as propenal or acrylic aldehyde, belongs to the class of organic compounds known as enals. These are alpha, beta unsaturated aldehydes, with the general chemical formula RC=C-CH=O in which the aldehydic C=O function is conjugated to the C=C double bond located at the alpha beta position. Acrolein 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. Acrolein 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. Acrolein is used as an etherification agent in the preparation of modified food starches. It is also used as an herbicide and algicide in water treatment. It can be produced by microorganisms, e.g. Clostridium perfringens. Acrolein is a relatively electrophilic compound and, due to its reactivity it shows high toxicity. It is a good Michael acceptor, making it a useful reaction tool 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 toxic and is a strong irritant to 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 mg/day per kilogram of body weight. Although acrolein occurs in French fries, the levels are only a few micrograms per kilogram. Acrolein has also been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID: 22626821). Acrolein is found in fruit aromas, black tea, carrot, cooked potato, cheeses, white wine, hydrolyzed soy protein, turkey, pork, beef fat and other foods. Acrolein has also been detected in the volatile fraction of Cannabis sativa samples obtained from police seizures (PMID: 26657499).