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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
- Results of element analysis: C: 55.1% H: 0.9% 0:44.0%
- Molecular weight: 218.1
- CAS number: 89-32-7
- Supplier: Mitsubishi Gas Chemical Company Inc.
- Lot number: 5X07 A
- Purity: Test item 99.92%
The test item was treated as 100% in purity.
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
5, 10, 20 and 30 min. after preparation of samples
Buffers:
Purified water was used as test medium (pH 7); no further buffer solutions were tested due to the chemical structure of the test item (dianhydride), However, as eluent for HPLC-analysis: buffer solution pH 2 (0.2 mol/L hydrochloric acid was adjusted to pH 2.0 with 0.2 mol/L potassium chloride solution) was used.
Estimation method (if used):
no estimation conducted
Details on test conditions:
See section "any other information on materials and methods ....".
Duration:
30 min
pH:
7
Temp.:
25 °C
Initial conc. measured:
1 000 mg/L
Number of replicates:
not given
Positive controls:
yes
Negative controls:
yes
Preliminary study:
The pre-test was performed at pH 2 and 7.4. In the measurement of UV-spectrum, the UV-spectrum measured immediately after the preparation of 5 mg/L solution (purified water) of PMDA has shown the same shape as that of pyromellitic acid. The UV spectra after 5, 10, 20 and 60 min from the preparation have also shown the same shape as that of pyromellitic acid. Therefore, it was considered that PMDA was converted to pyromellitic acid in water.
In the HPLC analysis for 100 mg/L solutions of PMDA, the detected peak was so similar to the peak of pyromellitic acid that water content in the test item solution was large. From this result, it was considered that the hydrolysis rate ofPMDA became so fast that water content in the test item solution was large, and that PMDA was converted to pyromellitic acid. Then, the UV spectrum measured immediately after the preparation of PMDA solution prepared with water was shown the same shape as that of pyromellitic acid. Therefore, it was considered that PMDA was easily converted to pyromellitic acid. Unknown peaks were so large that the content rate of acetonitrile in the test item solution was large. From this result, it was considered that the hydrolysis rate of PMDA became so slow that the content rate of acetonitrile in the test item solution was large. In the both of ion suppression chromatography and ion pair chromatography, the amount of pyromellitic acid produced from PMDA was almost 100% to the theoretical amount. Therefore, it was confirmed that pyromellitic acid was produced from PMDA.
In conclusion, based on the results of this pre-test, the main study was performed at pH 2 and 25°C. The main test was stopped after 30 minutes.
Transformation products:
yes
No.:
#1
% Recovery:
0
pH:
7
Temp.:
25 °C
Duration:
30 min
Remarks on result:
other: test stopped after 30 minutes due to quantitative hydrolysis of the test item
Key result
pH:
7
Temp.:
25 °C
DT50:
< 20 min
Type:
not specified
Results with reference substance:
the hydrolysis product PMA was tested as reference in UV- and HPLC-analysis to identify/confirm the chemical structure of the hydrolysis product
Validity criteria fulfilled:
yes
Conclusions:
The test item PMDA is unstable in water and hydrolyzes quickly in contact with water. Its half-life time t(1/2) in purified water is less than 20 minutes at 25°C.
Executive summary:

Pre- and main test were both performed in accordance with OECD no. 111. Based on the chemical structure (dianhydride), it was assumed that hydrolysis of PMDA to PMA will be fast. In the pre-test, it was confirmed that PMDA was completely hydrolyzed after one hour.

In the main test, the UV spectrum of PMDA solution prepared with acetonitrile/water (1/1 v/v) was different from that of PMDA solution prepared with acetonitrile immediately after the preparation, and was come close to that of pyromellitic acid solution prepared with acetonitrile/water (1/1 v/v) with time, and then was shown the same shape as that of pyromellitic acid solution after 20 min from the preparation of PMDA solution. The UV spectrum for PMDA solution prepared with water was shown the same shape as that of pyromellitic acid solution prepared with water immediately after the preparation Therefore, it is considered that PMDA was rapidly converted to pyromellitic acid in water and that the half-life of the test item is less than 20 min. In conclusion, the test item PMDA is unstable in water and hydrolyzes quickly in contact with water. Its half-life time t(1/2) in purified water is less than 20 minutes at 25°C.

Description of key information

The test item PMDA is unstable in water and hydrolyzes quickly in contact with water to PMA. Its half-life time t(1/2) in purified water is less than 20 minutes at 25°C.

Key value for chemical safety assessment

Half-life for hydrolysis:
20 min
at the temperature of:
25 °C

Additional information

Source: GLP-report