Chemical Properties
Crotonaldehyde is water-white (turns paleyellow on contact with air) with an irritating, pungent, suffocating odor. The chemical can turn pale yellow when it contacts air. The chemical has a molecular weight of 70.1, a boiling point of 219°F, and a freezing point of -101°F. The vapor pressure is 30mm Hg at 25°C and the specific gravity is 0.87. The lower explosive limit is 2.1% and the upper explosive limit is 15.5%. Crotonaldehyde may be incompatible with caustics, ammonia, strong oxidizers, nitric acid, and amines. It also has the ability to polymerize at high temperatures.
Uses
Crotonaldehyde (2-butenal, β-methyl acrolein, propylene aldehyde) is similar in structure to acrolein, as both are α,β-unsaturated aldehydes. This structural similarity leads to similar sensitizing and irritating properties of the two compounds. Crotonaldehyde is used industrially in the preparation of other chemicals (chiefly sorbic acid), flavoring agents, and can form endogenously and in the environment.
Crotonaldehyde is used in the manufacture ofbutyl alcohol, butyraldehyde, and in severalorganic synthesis.
Definition
ChEBI: Crotonaldehyde is an enal consisting of propene having a formyl group at the 1-position.
Preparation
Crotonaldehyde is prepared by the liquid phase condensation of acetaldehyde under the catalysis of alkali or anion exchange resin to form butanol aldehyde, which is then heated in dilute acid for condensation and dehydration.
General Description
Crotonaldehyde is a Water-white to straw-colored liquid with a pungent, suffocating odor. It is also used for the synthesis of butyl alcohol, butyraldehyde, quinaldine, thiophenes, pyridenes, dyes, pesticides, pharmaceuticals, rubber antioxidants, and chemical warfare agents and as a warning agent in locating breaks and leaks in pipes.
Air & Water Reactions
Highly flammable.
Reactivity Profile
Crotonaldehyde is an aldehyde. Crotonaldehyde can react violently with strong oxidizing reagents, e.g., reaction with conc. nitric acid leads to instantaneous ignition [Andrussow, L., Chim. Ind. (Paris), 1961, 86, p. 542]. In contact with strong acids or bases Crotonaldehyde will undergo an exothermic condensation reaction. Reaction with 1,3-butadiene is particularly violent [Greenlee, K. W., Chem. Eng. News, 1948, 26, p. 1985]. Crotonaldehyde may rapidly polymerize with ethyl acetoacetate (Soriano, D.S. et al. 1988. Journal of Chemical Education 65:637.).
Health Hazard
Although slightly less toxic, crotonaldehyde is similar chemically and toxicologically to acrolein, which is rated as extremely toxic. Toxic concentrations for human inhalation have been reported at 12 mg/m3/10 minutes. Irritant dose to human eye is 45 ppm. As with acrolein, vapor exposures cause severe and painful eye irritation, damage to cornea, lacrimation (tearing), irritation of nasal membranes, pulmonary edema (filling of lungs with fluid) and gastrointestinal distress when ingested.
Health Hazard
Crotonaldehyde causes severe irritation ofthe eyes, nose, lungs, and throat. Exposureto a concentration of 12 mg/m
3 in air for10 minutes can cause burning of the lungsand throat in humans. The symptoms ofinhalation toxicity in rats were excitement,behavioral change, convulsion, and death.The same symptoms were observed whencrotonaldehyde was administered subcutaneously.
LC50 value, inhalation (rats): 4000 mg/m
3/30 minutes
LD50 value, subcutaneous (rats): 140 mg/kg
Crotonaldehyde is less toxic than acroleinor formaldehyde. The toxic symptoms, however,were similar to those of acrolein. Thecis-isomer of crotonaldehyde is mutagenic; itcaused cancer in test animals. Oral administrationof 2660 mg/kg for 2 years producedtumor in the liver in rats. Evidence of carcinogenicityin humans is not yet confirmed.
Fire Hazard
Vapors form explosive mixtures in air or in sewers. Hazardous peroxides and acids emitted when heated to decomposition. Avoid nitric acid. Unstable, avoid oxygen, heat, elevated pressures. Hazardous polymerization may occur. Avoid contact with alkaline materials such as caustic ammonia or amines, or at elevated temperatures.
Safety Profile
Suspected carcinogen.
A poison by ingestion, subcutaneous, and
intraperitoneal routes. Mutation data
reported. A lachrymating material that is
very dangerous to the eyes. Human
respiratory system irritant by inhalation. Can
cause corneal burns and is irritating to the
skin. In case of contact, immediately flush
the skin or eyes with water for at least 15
minutes and get medlcal attention. See also
ALDEHYDES. Dangerous fire hazard
when exposed to heat or flame. To fight
fire, use alcohol foam, Con, dry chemical.
Incompatible with 1,3-butadiene and
oxidizing materials. When heated to
decomposition it emits acrid smoke and
fumes.
Potential Exposure
Crotonaldehyde is used as a warning agent in fuel gases and gas line leaks; as solvent; in Crotonaldehyde 935 chemical warfare; as an intermediate in the manufacture of n-butanol and crotonic and sorbic acids; in resin and rubber antioxidant manufacture; also used as a solvent in mineral oil purification; as an alcohol denaturant.
Shipping
UN1143 Crotonaldehyde or Crotonaldehyde, stabilized, Hazard class: 6.1; Labels: 6.1-Poison Inhalation Hazard, 3-Flammable liquid, Inhalation Hazard Zone B.
Incompatibilities
Vapors may form explosive mixture with air. A strong reducing agent. Readily converted by oxygen to peroxides and acids; heat or contact with alkalis and many other substances may cause polymerization. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, nonoxidizing mineral acids; ammonia, organic amines; aliphatic amines; aromatic amines; 1,3-butadiene, strong bases. Liquid attacks some plastics, rubber, and coatings
Waste Disposal
Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed. May be absorbed on vermiculite and burned in open incinerator or dissolved in solvent and sprayed into incinerator
