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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
secondary literature
Justification for type of information:
origninal report not available, but the substance was assessed in ICCA/OECD-HPV program, giving it a high reliabbility.
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
yes
Analytical monitoring:
yes
Details on test conditions:
Pretest:
- test concentrations: 1000 mg/L
- pH 4, 7, 9 and 50 °C
Main test:
- test concentration: 1000 mg/L
- pH 4, 60 °C, 70 °C, 80 °C
- tests were performed in duplicate
Preliminary study:
degradation observed at pH 4
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
breakdown products not studied
pH:
4
Temp.:
25 °C
DT50:
72.1 d
Type:
other: extrapolated
pH:
4
Temp.:
60 °C
DT50:
8.92 d
Type:
(pseudo-)first order (= half-life)
pH:
4
Temp.:
70 °C
DT50:
3.68 d
Type:
(pseudo-)first order (= half-life)
pH:
4
Temp.:
80 °C
DT50:
3.11 d
Type:
(pseudo-)first order (= half-life)

m-toluidine is stable in water at pH 7 and pH 9

Validity criteria fulfilled:
not specified
Remarks:
Since the test is poorly reported the validity criteria cannot be assessed sufficiently. Nevertheless the test is considered as valid based on the data given.
Conclusions:
m-Toluidine is stable at pH 7.0 and 9.0, but it is hydrolysed with the half-life time of 72.1 days at pH 4.0.
Executive summary:

According to the OECD Guideline 111 (Hydrolysis as a Function of pH) m-toluidine revealed a half-life of 72.1 d at pH 4 and 25°C. At pH 7.0 and 9.0 m-toluidine was stable with a half-life of > 1 year.

Description of key information

m-Toluidine is stable (half-life time >1 year) at pH 7.0 and 9.0, but it

is hydrolysed with the half-life time of 72.1 days at pH 4.0.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 yr
at the temperature of:
25 °C

Additional information

Stability of m-toluidine in water was investigated according to the OECD Guideline 111 (Hydrolysis as a Function of pH).

The preliminary test was performed at 1000 mg/L and at 50 °C for 5 days in each buffer of pH 4.0, 7.0 and 9.0. The kinetics of the hydrolysis was studied at 1000 mg/L and at 60, 70 and 80 °C in the buffer of pH 4.0, at which the test substance was unstable in the preliminary test. The first-order rate constants of the hydrolysis at three temperatures were calculated by lease squares method. The rate constant of hydrolysis at 25°C was calculated by extrapolating the linear regression equation between the logarithm of the rate constant and reciprocal of temperature. The half-life time of hydrolysis was calculated from the rate constant. All tests were performed in duplicate. The concentration was determined with HPLC.

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