acrolein

Acrolein
IUPAC name	Prop-2-enal
Other names	Acraldehyde Acrylic Aldehyde Allyl Aldehyde Ethylene Aldehyde
Identifiers
CAS number	107-02-8 Y
PubChem	7847
SMILES	O=C\C=C
InChI	1/C3H4O/c1-2-3-4/h2-3H,1H2
InChI key	HGINCPLSRVDWNT-UHFFFAOYAQ
ChemSpider ID	7559
Properties
Molecular formula	C3H4O
Molar mass	56.06 g mol−1
Appearance	Colorless to yellow liquid. Irritating odor.
Melting point	-88 °C (-126 °F)
Boiling point	53 °C (127 °F)
Solubility in water	Appreciable (> 10%)
Hazards
MSDS	JT Baker MSDS
Main hazards	Highly poisonous. Causes severe irritation to exposed membranes. Extremely flammable liquid and vapor.
NFPA 704	3 4 3
Flash point	-26°C
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Acrolein (systematic name: propenal) is the simplest unsaturated aldehyde. It is produced widely but is most often immediately reacted with other products due to its instability and toxicity. It has a piercing, disagreeable, acrid smell similar to that of burning fat.

Synthesis

Acrolein is prepared industrially by oxidation of propene. Efforts are under way to use propane as feedstock for the synthesis; however, this is more difficult.^[1] Several million tons of acrolein are produced each year.

When glycerol is heated to 280 °C, it decomposes into acrolein.^[2] Acrolein may also be produced on lab scale by the reaction of potassium bisulfate on glycerol (glycerine).^[3]

Uses

Acrolein is used in the preparation of polyester resin, polyurethane, propylene glycol, acrylic acid, acrylonitrile, and glycerol. Acrolein tends to polymerize when left at room temperature, leaving a gummy yellowish residue with a putrid odor. 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 is sometimes used as a fixative in preparation of biological specimens for electron microscopy.^[4] It is also used as a contact herbicide to control submersed and floating weeds, as well as algae, in irrigation canals.

Health risks

Acrolein is a severe pulmonary irritant and lachrymatory agent. It was used as a chemical weapon during World War I. It is, however, not outlawed by the Chemical Weapons Convention. Skin exposure to acrolein causes serious damage. Acrolein concentrations of 2 ppm are immediately harmful. Acrolein is not a suspected human carcinogen; no studies have been conducted on the carcinogenic effects of acrolein on humans, but studies on rats have shown an increase in cancerous tumors from ingestion, but not from inhalation. ^[5] In October 2006, researchers found connections between acrolein in the smoke from tobacco cigarettes and the risk of lung cancer.^[6] Furthermore, acrolein is a toxic metabolite of cyclophosphamide, a cytotoxic chemotherapy agent, and results in hemorrhagic cystitis.^[7] N-acetylcysteine or mesna are used to counteract the acrolein.

EPA method 603 is designed to measure acrolein in industrial and municipal wastewater streams.^[8]

Acrolein test

Acrolein test is a test for the presence of glycerin or fats. A sample is heated with potassium bisulfate, and acrolein is released if the test is positive.^[9] When a fat is heated strongly in the presence of a dehydrating agent such as KHSO₄, the glycerol portion of the molecule is dehydrated to form the unsaturated aldehyde, acrolein (CH₂=CH-CHO), which has the peculiar odor of burnt grease.

References