Registration Dossier

Diss Factsheets

Environmental fate & pathways

Hydrolysis

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
03/1989 to 02/1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
EPA OTS 796.3500 (Hydrolysis as a Function of pH at 25°C)
Version / remarks:
pH 3, 7 and 11
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
- Name of test material (as cited in study report): Methyl Methacrylate-Carboxy-14C (14C-Methyl Methacrylate)
- Analytical purity: 98.8% (GC-FID); 99.2% (HPLC-UV @254 nm)
- Radiochemical purity (if radiolabelling): 100%
- Specific activity (if radiolabelling): 1.4 mCi/mmole; 31043 dpm/µg
- Lot/batch No.: #1l8F9226
- Supplier: Sigma Chemical Company, St. Louis, MO 63178
- Storage condition of test material: 0-5°C
- Concentration: 1.0 mCi/ml in acetonitrile (sealed ampule); 71. 51 mg/mL

- Name of test material (as cited in study report): methyl methacrylate
- Lot/batch No.: Lot #5-0590-88 (containing 15 ppm MEHQ)
- Storage condition of test material: room temperature
- Supplier: Rohm and Haas Company, Philadelphia, PA 19105
Radiolabelling:
yes
Analytical monitoring:
yes
Buffers:
PREPARATION OF BUFFERS
1) pH 3.0 - Prepared 500 mL of 0.01 M potassium hydrogen phthalate and adjusted pH to 3.00 ± 0.05 with 0.01 N hydrochloric acid. Diluted to 1000 mL with HPLC grade water.
2) pH 7.0 - Prepared 500 mL of 0.01 M potassium dihydrogen phosphate and adjusted pH to 7.00 ± 0.05 with 0.01 N sodium hydroxide. Diluted to 1000 mL with HPLC grade water.
3) pH 11.0 - Prepared 500 mL of 0.005 M sodium bicarbonate and adjusted pH to 11.00 ± 0.05 with 0.01 N sodium hydroxide. Diluted to 1000 mL with HPLC grade water.
Duration:
28 d
pH:
3
Temp.:
25 °C
Initial conc. measured:
10 mg/L
Duration:
28 d
pH:
7
Temp.:
25 °C
Initial conc. measured:
10 mg/L
Duration:
28 d
pH:
11
Temp.:
25 °C
Initial conc. measured:
10 mg/L
Number of replicates:
Three vials for each pH.
No.:
#1
Key result
pH:
3
Temp.:
25 °C
Remarks on result:
other:
Key result
pH:
7
Temp.:
25 °C
DT50:
53 mo
Key result
pH:
11
Temp.:
25 °C
DT50:
2.4 h
Other kinetic parameters:
Methyl methacrylate is hydrolytically stable at pH 3 and only few hydrolysis occured at pH 7.
Kinematic parameters at pH 11 see table below.


At pH 3, 14C-methyl methacrylate was stable to hydrolysis

Only few hydrolysis occured at pH 7.

Kinetic parameters of hydrolysis at pH 11 are as follows:

Sample Name

Time

(min.)

% 14 C-Methyl methacrylate

Hour 0 pH ll A

11

95.80

Hour 0 pH ll B

24

90.27

Hour 0 pH ll C

36

84.10

 

 

 

Hour 1 pH ll A

69

73.71

Hour 1 pH ll B

81

67.75

Hour 1 pH ll C

93

65.61

 

 

 

Hour 2 pH ll A

108

58.87

Hour 2 pH ll B

129

53.93

Hour 2 pH ll C

141

52.00

 

 

 

Hour 3 pH ll A

179

43.74

Hour 3 pH ll B

192

40.36

Hour 3 pH ll C

204

37.72

 

 

 

Hour 4 pH ll A

224

30.29

Hour 4 pH ll B

255

27.04

Hour 4 pH ll C

284

22.20

 

 

 

Hour 5 pH ll A

321

26.33

Hour 5 pH ll B

334

19.31

Hour 5 pH ll C

346

17.00

 

 

 

Hour 6 pH ll A

360

18.27

Hour 6 pH ll B

274

18.73

Hour 6 pH ll C

386

15.79

 

 

 

Hour 7 pH ll A

410

14.70

Hour 7 pH ll B

432

7.71

Hour 7 pH ll C

445

13.71

 

 

 

Hour 8 pH ll A

466

11.21

Hour 8 pH ll B

484

9.81

Hour 8 pH ll C

497

9.88

 

 

 

 

Conclusions:
In a valid guideline study, the hydrolysis half-life of MMA at pH 7 and 25 C was 53 months.
Executive summary:

Hydrolysis as a function of pH was tested acc. EPA OTS 796 3500 at pH 3, 7 and 11 at 25 °C with radiolabelled 14C- Methyl methacrylate was stable within 28 days at pH 3. Hydrolysis half-life of MMA at pH 7 and 25 °C was 53 months (less than 2 % hydrolysis within 28 days), at pH 11 hydrolysis half-life was 2.4 hours. The deceted transformation product was 14C- methacrylic acid.

Description of key information

MMA, like other lower methacrylate esters, is stable at neutral and acidic pH. Under normal environmental conditions, abiotic degradation by hydrolysis is slow and not expected to play an important role in the degradation of MMA in the environment. Hydrolysis time in alkali pH 11 was 2.4 hours.

Key value for chemical safety assessment

Additional information

Abiotic degradation by hydrolyses of methyl methacrylate was measured in a GLP U.S.-EPA guideline study (Archer, 1990, cited in EU-RAR 2002). The measured half-life (t 1/2 ) for 14C-methyl methacrylate at 25 °C is 143 minutes at pH 11. Since less than 2% hydrolyses occurred for 14C-methyl methacrylate at pH 7 over 28 days, the approximate half-life calculated from the initial and final concentration for pH 7 was 1600 days. 14C-methyl methacrylate is stable to hydrolysis at pH 3. Nevertheless, since methyl methacrylate is readily biodegradable, hydrolysis is not the predominate degradation process.

Categories Display