| Chemical Abstract Number (CAS #) |
78591
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| Synonyms | Isophorone |
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3,5,5-Trimethyl-2-cyclohexenone |
| Analytical Methods |
EPA Method 609 |
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EPA Method 625 |
EPA Method 8250A |
| Molecular Formula | C9H14O |
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| Use | SOLVENT FOR LACQUERS & PLASTICS
SOLVENT FOR MANY OILS, FATS, GUMS, RESINS, NITROCELLULOSE, &
VINYL-RESIN COPOLYMERS
CHEM INT FOR 3,3,5-TRIMETHYLCYCLOHEXANOL, & 3,5-XYLENOL; SPECIALTY
SOLVENT
IN PESTICIDES; STOVING LACQUERS
SOLVENT IN ACRYLIC, EPOXY, POLYESTER AND SILICONE RESIN SYSTEMS
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| Apparent Color | WATER-CLEAR LIQ
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| Odor | PEPPERMINT-LIKE ; Camphor-like
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| Boiling Point | 214 DEG C @ 754 MM HG; 99 DEG C @ 18 MM HG
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| Melting Point | -8.1 DEG C
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| Molecular Weight | 138.2
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| Density | 0.9229 AT 20 DEG C
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| Odor Threshold Concentration | Odor detection in air= 2.00 ppm. Purity not specified.
Odor recognition in air= 5.40 ppm. Purity not specified.
1 mg/cu m (odor low); 50 mg/cu m (odor high)
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| Sensitivity Data | MEN EXPOSED AT 40, 85, 200 & 400 PPM ISOPHORONE EXPERIENCED
EYE, NOSE, AND THROAT IRRITATION.
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| Environmental Impact | Isophorone is used as a solvent for a large number of natural and synthetic polymers,
resins, waxes, fats, oils, and pesticides, in addition to being used as a chemical intermediate. As a
result this compound may be released to the environment from a wide variety of industries, from
the disposal of many different products and during the application of some pesticides. If released
to soil or water, isophorone is predicted to be removed partially by volatilization (half-life 7.5
days from a model river) and partially by biodegradation. Potential biodegradation products
include: 3,5,5-trimethyl-2-cyclohexene-1,4-dione, 3,5,5-trimethylcyclohexane-1,4-dione,
(S)-4-hydroxy-3,5,5-trimethyl-2-cyclohexen-1-one, and
3-hydroxymethyl-5,5-dimethyl-2-cyclhexen-1-one. Potential exists for contamination of
groundwater by leaching through soil. Isophorone is not expected to sorb significantly to
suspended solids and sediments in water, bioaccumulate significantly in aquatic organisms,
photolyze, oxidize by reaction with singlet oxygen or alkyperoxy radicals in water, or undergo
chemical hydrolysis. If released to air, isophorone is expected to exist primarily in the vapor
phase. Reaction with ozone is expected to be the dominant removal process and reaction with
photochemically generated hydroxyl radicals is expected to be of minor importance (overall
half-life 32 min). Isophorone emitted to the atmosphere in particulate form may be removed by
wet or dry deposition. The most probable route of human exposure to isophorone in the ambient
environment is by ingestion of drinking water contaminated with this compound. Worker
exposure may occur by inhalation or dermal contact.
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| Environmental Fate | TERRESTRIAL FATE: If released to soil, isophorone may be removed partially by
volatilization and partially by biodegradation.
AQUATIC FATE: If released to water, isophorone may biodegrade or it may volatilize (half-life
7.5 days from a model river(1,SRC). Results of biodegradation screening studies are conflicting:
However, it has been shown that mixed microbial populations are capable of degrading
isophorone fairly rapidly. Potential biodegradation products include
3,5,5-trimethyl-2-cyclohexane-1,4-dione, 3,5,5-trimethylcyclohexane-1,4-dione,
(S)-4-hydroxyl-3,5,5-trimethyl-2-cyclohexen-1-one and
3-hydroxymethyl-5,5-dimethyl-2-cyclohexen-1-one . Adsorption to suspended solids and
sediments, bioacculmulation in aquatic organisms, photolysis, oxidation by reaction with singlet
oxygen or alkylperoxy radicals and chemical hydrolysis are not expected to be important fate
process in water.
ATMOSPHERIC FATE: Based on a vapor pressure of 0.38 mm Hg at 20 deg C, isophorone is
expected to exist primarily in the vapor phase in the atmosphere(1,2). Isophorone is predicted to
be removed from the atmosphere by reaction with ozone (t/2 39 minutes) and reaction with
photochemically generated hydroxyl radicals (t/2 3 hours). The overall half-life for isophorone has
been estimated to be 32 minutes . Direct photolysis is not expected to occur. Isophorone
emitted to the atmosphere in particulate form may be removed by wet or dry deposition.
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| Drinking Water Impact | SURFACE WATER: USEPA STORET Data Base - 795 water samples, 1% pos.,
median concn <10.00 ug/l . During Aug 1977 in Delaware River at river mile 106, 108, and 110
isophorone concentration was found to be 3, 0.6 and <0.01 ug/l, respectively . Isophorone was
detected in the St. Joseph River and not detected in the Cuyahoga River . USEPA National
Urban Runoff Program (NURP) results as of July 1982 indicate that isophorone was found in
runoff in 1/19 cities across USA . 10 ug/l was detected in urban runoff of Washington DC .
DRINKING WATER: Isophorone identified in finished drinking water from: Cincinnati, OH -
Oct 1978 and Jan 1980; Philadelphia, PA - Feb 1976; Ottumwa, IA - Sept 1976; and Seattle, WA
- Nov 1976 . During the USEPA 1974 National Organics Reconnaissance Survey (NORS)
isophorone was detected in 1/10 finished drinking water supplies . Approximately 0.02 ug/l was
found in drinking water from Cincinnati, OH . Trace levels detected in Philadelpha, PA drinking
water during Aug 1977 . Detected in drinking water from New Orleans, LA during 1974, max
concn 2.9 ug/l .
GROUNDWATER: Identified in groundwater in the Netherlands, max concn 10 ug/l .
EPA maintains an inventory of organic compounds that have been isolated and identified in
drinking water in the USA. Isophorone was detected at concentrations as high as 9.5 ug/l.
EFFL: USEPA STORET Data Base - 1272 effluent samples, 1.6% pos, median concn <10.0
ug/l . Isophorone has been found in the treated wastewater from the following industries: iron
and steel mfg, 1/5 samples pos, concn 170 ug/l; Coil coating, 5/31 samples pos, max concn 560
ug/l, mean concn 120 ug/l; Foundries, 7/7 samples pos, max concn 28 ug/l, mean concn 12 ug/l;
photographic equipment and supplies, 2/4 samples pos, max concn 10 ug/l, mean concn 10 ug/l;
paint and ink formulation, 1/1 samples pos, concn <7 ug/l; automobile tire plant, 40 ug/l; and oil
shale retorting, 340-5800 ug/l(2,3,4). The influent and effluent of the Philadelphia (PA) Northeast
Sewage Treatment plant during Aug 1977 was 100 and 10 ug/l, respectively .
Isophorone was also identified as a contaminant (approximate concn, 0.04 mg/l) in the waste
water from a tire manufacturing plant.
Isophorone has been detected in the effluents from latex and chemical plants in Alabama, but no
levels were reported.
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