| Chemical Abstract Number (CAS #) |
123739
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| Synonyms | Crotonaldehyde, (E) |
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2-Butenal, (E)- |
| Analytical Methods |
EPA Method 554 |
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EPA Method 8315 |
| Molecular Formula | C4H6O |
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| Use | CHEM INT FOR N-BUTYL ALCOHOL, QUINALDINE, CROTONIC ACID,
SURFACE-ACTIVE AGENTS, TEXTILE & PAPER SIZES, INSECTICIDES & FLAVORING
AGENTS; FUEL-GAS WARNING AGENT; SOLVENT FOR POLYVINYL CHLORIDE;
ALCOHOL DENATURANT; LEATHER TANNING AGENT
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| Boiling Point | 104 DEG C
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| Melting Point | -74 DEG C
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| Molecular Weight | 70.09
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| Density | 0.869 AT 20 DEG C/20 DEG C
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| Odor Threshold Concentration | Odor detection in air 5.25X10 2 ppb (gas chromatically pure)
Odor low: 0.1050 mg/cu m; Odor high: 3.0000 mg/cu m
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| Sensitivity Data | Crotonaldehyde vapor is so highly irritant to the eyes that people are unable to remain in
the presence of dangerous concn IDLH 400 mg/cu m/; at 45 ppm the odor is extremely
obnoxious & there is considerable eye discomfort.
Its strongly lacrimatory vapors make it a valuable warning agent.
Its most pronounced feature is its irritating effect on the nose, pharynx, & larynx.
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| Environmental Impact | Crotonaldehyde (both the trans- and cis-isomers) is released to the atmosphere from the
combustion of wood, polymers, and tobacco, in gasoline, diesel, and turbine engine exhausts, and
in volcanic gases. If released to the atmosphere, trans-crotonaldehyde degrades rapidly (typical
half-life of 11 hours) via reaction with photochemically produced hydroxyl radicals. If released to
water in low concentrations, crotonaldehyde can degrade via reaction with photochemically
produced oxidants (estimated half-life of 5 days) and volatilize (estimated half-lives of 40 hours
from a model river one meter deep and 18.3 days from a pond). If released to soil, crotonaldehyde
is susceptible to significant leaching. Evaporation from dry surfaces can be expected to occur. If
released to the environment in a spill situation, a significant fraction of the spill may polymerize.
The general population may be exposed to crotonaldehyde through inhalation of tobacco smoke,
gasoline and diesel engine exhausts, and wood combustion. Occupational exposure via inhalation
and dermal contact is possible at sites of its commercial production and use.
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| Environmental Fate | TERRESTRIAL FATE: Crotonaldehyde is expected to leach in soil based on estimated
Koc values of 6-50. Its relatively high vapor pressure of 30 mm Hg at 20 deg C indicates that
evaporation from terrestrial surfaces may occur relatively rapidly. One screening study suggests
that crotonaldehyde may be biodegradable, but data are insufficient to predict the importance of
biodegradation in the environment. Crotonaldehyde readily polymerizes; therefore, if it is released
to soil in a spill situation, a significant fraction may polymerize.
AQUATIC FATE: When present in water in low concentrations, crotonaldehyde can be
degraded by photochemically produced oxidants and transported to the atmosphere via
volatilization. In sunlit natural water, olefinic structures (similar to crotonaldehyde) decompose
via hydroxyl radicals and singlet oxygen at a combined half-life rate of about 5 days(1,SRC).
Estimated volatilization half-lives are 40 hours for a model river (1 meter deep) and 18.3 days for
an environmental pond(2,3). One screening study suggests that crotonaldehyde may be
biodegradable, but data are insufficient to predict the importance of biodegradation in the
environment. Aquatic hydrolysis, bioconcentration, and adsorption to sediment are not significant.
If released in a spill situation, a significant fraction of the crotonaldehyde may polymerize.
ATMOSPHERIC FATE: Crotonaldehyde is expected to exist almost entirely in the vapor-phase
in the ambient atmosphere , based on a vapor pressure of 30 mm Hg at 20 deg C(1,SRC).
trans-Crotonaldehyde reacts rapidly in the vapor-phase (typical half-life of 11 hours) with
photochemically produced hydroxyl radicals. Reaction with ozone also occurs, but the rate
(average half-life of 15.5 days) is not significant in comparison to hydroxyl radical reaction.
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| Drinking Water Impact | DRINKING WATER: Crotonaldehyde (isomer not reported) has reportedly been
identified in a drinking water sample (source and concn not reported) . Crotonaldehyde (steric
form not reported) has reportedly been identified in a drinking water sample from the US (concn
not reported) .
EFFL: Crotonaldehyde (steric form not reported) was detected in 1 (concn <10ppb) of 6 US
industrial effluents . A photographic industry wastewater effluent was found to contain
crotonaldehyde . Crotonaldehyde concns of 0.006-0.116 g/kg were detected in emissions from
wood burning fireplaces . Crotonaldehyde has been detected in exhausts from both gasoline and
diesel engines .
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