| Chemical |
Methacrylic acid |
| CAS-number : |
79-41-4 |
| |
| Synonyms : |
| 2-methyl-2-propenoic acid |
| 2-methylacrylic acid |
| 2-Methylpropenoic acid |
| 2-Propenoic acid, 2-methyl- |
| alpha-methacrylic acid |
| |
| Sumformula of the chemical : |
| C4H6O2
|
| EINECS-number : |
| 2012044 |
| |
| State and appearance : |
Liquid or colorless crystals.
|
| |
| Odor : |
Acrid, repulsive odor.
|
| |
| Molecular weight : |
86.1 |
| |
| Spesicif gravity (water=1) : |
| 1.02 |
water = 1 |
| |
| Vapor pressure, mmHg : |
| 0.65 |
20 °C |
| 0.975 |
25 °C, HSDB 1998 |
| |
| Water solubility, mg/l : |
| 89000 |
25 °, HSDB 1998 |
| |
| Melting point, °C : |
| 15 |
|
| 16 |
HSDB 1998 |
| |
| Boiling point, °C : |
| 163 |
HSDB 1998 |
| |
| pKa : |
| 4.66 |
HSDB 1998 |
| |
| Log octanol/water coefficient, log Pow : |
| 0.93 |
HSDB 1998 |
| |
| Henry's law constant, Pa x m3/mol : |
| 0.13 |
HSDB 1998 |
| |
| Volatilization : |
Based upon a water solubility of 89 g/l and a vapor pressure of
0.975 mmHg at 25 °, the Henry's Law constant for methacrylic
acid has been calculated to be 2.24X10-6 atm m3/mol.
The
volatilization half-life from a model river (1 m deep flowing 1
m/sec with a wind speed of 3 m/sec) has been estimated to be
27.5 days.
The volatilization half-life from a model pond has
been estimated to be 298 days (HSDB 1998).
|
| |
| Adsorption/desorption : |
Using a log Kow of 0.93, a Koc of 76 has been calculated using
a recommended regression-derived equation.
The estimated Koc
indicates that methacrylic acid will not be expected to adsorb
significantly to soil, sediment or suspended particulate matter
(HSDB 1998).
Methacrylic acid was weekly adsorped to the soil (five soils:
sandy loam, loamy sand, two loams, a clay loam).
To the loamy
sand, the having the lowest organic carbon content (0.46 %),
methacrylic acid was most strongly adsorped.
The Freundlich
coefficient values for adsorption phase ranged from 0.076 to
0.24.
For the five soils the Koc's for methacrylic acid ranged
from 1.7 to 52.
Once adsorped to the soil, methacrylic acid was
less readly desorped.
The Freunlich coefficient values for the
three desoprtion phases ranged from 0.069 to 2.04; calculated
desorption conctants ranged from 3.2 to 144 (IUCLID 2000).
|
| |
| Mobility : |
The estimated Koc indicates that methacrylic acid will exhibit
a high mobility in soil (HSDB 1998).
Calculation according Mackay, Level I
methacrylic acid (%) in different comparments:
air 2.41 %
water 97.46 %
soil 0.07 %
sediment 0.06 %
suspended matter, aquatic 0.00 %
biota 0.00 %
(IUCLID 2000).
|
| |
| Photochemical degradation in air : |
Methacrylic acid may directly photolyze in sunlight based upon
its slight adsorption of light at wavelenghts > 290 nm in
methanol solution.
Methacrylic acid will be susceptible to
photooxidation via vapor phase reaction with photochemically
produced hydroxyl radicals and ozone.
An atmospheric half-life
of 6.12 hours at an atmospheric concentration of 5X10+5 radicals
per cm3 and 7X10+11 ozone molecules per cm3 has been estimated
for this process (HSDB 1998).
|
| |
| Chemical oxygen demand, g O2/g : |
| 1.7 |
IUCLID 2000 |
| |
| Biochemical oxygen demand, g O2/g : |
| 0.9 |
BOD5, IUCLID 2000 |
| |
| Total degradation in water : |
Methacrylic acid is rapidly biodegrade in tests using adapted
sludge inoculums under aerobis conditions.
Aerobic standard
dilution tests using sewage inoculums provided: 53 %
theoretical BOD after 5 days incubation; 68 % and 86 %
theoretical COD after 19 and 42 days, respectively.
Methacrylic
acid and other acrylic acid derivatives create considerable
oxygen demand which can cause problems in water bodies
receiving these wastes (HSDB 1998).
Biodegradation:
type: aerobic
inoculum: activated sewage sludge bacteria
concentration: 3 mg/l related to test substance
degradation: 86 % after 28 days
result: readily biodegradable
method: OECD Guide-line 301 D
(IUCLID 2000).
Biodegradation:
type: aerobic
inoculum: sludge, industrial
concentration: related to DOC
degradation: > 95 % after 28 day
method: OECD Guide-line 302 B "Inherent biodegradability"
(IUCLID 2000).
|
| |
| Other information of degradation : |
Based upon a pKa in water solution of 4.43 methacrylic acid is
expected to remain in the dissociated state in aqueous solution
under normal environmental conditions (IUCLID 2000).
Methacrylic acid was found to be stable to hydrolysis at 25 °C
at pH 3, 7 and 11 (IUCLID 2000).
BOD5/COD = 0.53 (IUCLID 2000).
|
| |
| Other information of bioaccumulation : |
Using a log Kow of 0.93, a BCF of 3.0 has been calculated using
a recommended regression-derived equation.
This estimates BCF
indicates that mathacrylic acid will not be expected to
bioconcetrate in aquatic organisms (HSDB 1998).
|
| |
| EC50 values to algae, mg/l : |
| 0.59 |
96 hr, Selenastrum capricornutum, OECD Guide-line 201 |
| |
IUCLID 2000 |
| |
| NOEC values to algae, mg/l : |
| 0.38 |
96 hr, Selenastrum capricornutum, IUCLID 2000 |
| |
| EC50 values to crustaceans, mg/l : |
| 100 |
100 - 180 mg/l, 284 hr, Daphnia magna, |
| 180 |
OECD Guide-line 202, IUCLID 2000 |
| |
-- |
| 130 |
> 130 mg/l, 48 hr, Daphnia magna, IUCLID 2000 |
| |
| NOEC values to crustaceans, mg/l : |
| 56 |
24 hr, Daphnia magna, IUCLID 2000 |
| 130 |
48 hr, Daphnia magna, IUCLID 2000 |
| |
| LC50 values to fishes, mg/l : |
| 100 |
> 100 - 180 mg/l, 96 hr, Brachydanio rerio, |
| 180 |
OECD Guide-line 203 |
| 85 |
96 hr, Oncorhynchus mykiss |
| 224 |
48 hr, Leuciscus idus melanotus |
| |
IUCLID 2000 |
| |
| NOEC values to fishes, mg/l : |
| 12 |
96 hr, Oncorhynchus mykiss |
| 100 |
96 hr, Brachydanio rerio |
| 200 |
48 hr, Leuciscus idus melanotus |
| |
IUCLID 2000 |
References |
| 3114 | HSDB Database 1992 -.
Hazardous Substances Data Bank.
US.
National Library of Medicine.
TOMES Plus CD-ROM.
|
| 3253 | IUCLID 1995 -.
International Uniform Chemical Information
Database.
European Commission.
European Chemicals Bureau.
Existing Chemicals.
Ispra, Italy.
|
