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Hydrolysis

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Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Remarks:
Excerpt from US EPA report. Expert opinion. Data extracted from Revised Robust Summaries.
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
not specified
GLP compliance:
yes
Specific details on test material used for the study:
Butyl glycidyl ether, CAS 2426-08-6, Purity: 99.8% Measured
Radiolabelling:
not specified
Analytical monitoring:
not specified
Details on sampling:
Time points for the preliminary test were time zero and Day 5. Times for the definitive tests were chosen so that at least six time points were sampled at 20-70% of total hydrolysis.
Positive controls:
not specified
Transformation products:
no
Key result
pH:
4
Temp.:
20 °C
DT50:
ca. 0.3 h
Key result
pH:
7
Temp.:
20 °C
DT50:
20.3 d
Other kinetic parameters:
The rate of hydrolysis was extrapolated to 25°C for pH 4.0 and 7.0 using the Arrhenius equation: k(obs) = Ae-(Ea/RT) or ln k(obs) = Ln A -Ea/RT
Details on results:
t1/2 pH 4: ca. 1 hour(s) at 10 ºC

The rate of hydrolysis was determined to be:
19.64 l/s x l0e5 for pH 4.0 (10ºC),
68.75 l/s x l0e5 for pH 4.0 (20ºC),
0.04 l/s x l0e5 for pH 7.0 (20°C)
0.26 l/s x l0e5 for pH 7.0 (40°C)

There was not a determined rate of hydrolysis for pH 9.0 (50°C) since hydrolysis was less than 10%.

The extrapolated rates of hydrolysis for:

12.44 l/s x l0e5 for pH 4.0 (25°C)
6.26 l/s x l0e5 for pH 7.0 (25°C)

Therefore, the test substance, n-Butyl glycidyl ether, CAS RN 2426-08-6, underwent rapid hydrolysis at pH 4.0. The rate of hydrolysis slowed down as the pH was increased.
Validity criteria fulfilled:
not specified
Remarks:
Excerpt from US EPA report. Data extracted from Revised Robust Summaries.
Conclusions:
The test substance n-Butyl glycidyl ether (CAS No. 2426-08-6), underwent rapid hydrolysis at pH 4.0. The rate of hydrolysis slowed down as the pH was increased.
Executive summary:

In the course of a OECD 111 study butyl glycidyl ether has been assessed to be readily and moderately hydrolysable at pH 4 and 7 (with half-times of 0.3 hours and 20.3 days, respectively). At pH 9 and 50 °C no remarkable hydrolysis rate has been determined, as the hydrolysis rate was less than 10 % under these conditions.

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Expert opinion. Data extracted from revised robust summaries.
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
not specified
GLP compliance:
yes
Analytical monitoring:
not specified
Details on sampling:
not specified
Details on test conditions:
not specified
Positive controls:
not specified
Negative controls:
not specified
Transformation products:
not specified
Key result
pH:
4
Temp.:
25 °C
DT50:
2.83 d
Key result
pH:
7
Temp.:
25 °C
DT50:
3.66 d
Key result
pH:
9
Temp.:
25 °C
DT50:
2.22 d
Validity criteria fulfilled:
not specified
Conclusions:
The substance is readily hydrolysable.
Executive summary:

In the course of a OECD 111 study glycidyl methacrylate has been assessed to be readily hydrolysable (with T1/2 = 2.83, 3.66 and 2.22 day at pH 4,7,and 9, respectively).

Endpoint:
hydrolysis
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
The source compound n-butyl glycidyl ether (EC 219-376-4, CAS 2426-08-6) is considered a suitable read across partner for tert-butyl glycidyl ether (EC 231-640-0, CAS 7665-72-7). Both substances are structural isomers regarding the alkyl chain structure.

Both ethers have similar physico-chemical properties. Both are highly water soluble (20 g/L vs 90 g/L), exhibit similar log Kow values (0.63 vs 0.97), similar boiling points (169 °C vs 152 °C) and vapour pressure (3.5 hPA vs 6.26 hPa) compared to tert-butyl glycidyl ether.

Under the conditions of the hydrolysis test, both substances will react with water: in the course of a ring opening, a vicinal diol will be formed as the final product (the ether group will remain intact under the conditions of this test). Since both substances have alkyl chain groups with identical molecular weight (n-butyl and tert-butyl), it can reasonably be inferred that the ring opening in tBGE will take place within the same magnitude as that of n-BGE.
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
not specified
GLP compliance:
yes
Radiolabelling:
not specified
Analytical monitoring:
not specified
Details on sampling:
Time points for the preliminary test were time zero and Day 5. Times for the definitive tests were chosen so that at least six time points were sampled at 20-70% of total hydrolysis.
Positive controls:
not specified
Preliminary study:
A preliminary experiment was used to determine the approximate rate of hydrolysis of the test substance and the course of further testing. This test was performed at all three pH levels (4.0, 7.0 and 9.0) at 50 +/- 0.1 ºC for five days and the outcomes determined further testing. A sample of test substance was weighed into an autoclaved vial of sterile buffer solution (pH 4.0, 7.0 and 9.0) and then dispersed by syringe to appropriately labeled, autoclaved containers using aseptic technique. The containers were sealed, covered with foil, purged with nitrogen and placed in the appropriate constant temperature bath until retrieved for sampling. The quantity of containers was sufficient to allow for removal of one container at each time point.
Transformation products:
not specified
Key result
pH:
4
Temp.:
20 °C
DT50:
ca. 0.3 h
Key result
pH:
7
Temp.:
20 °C
DT50:
20.3 d
Key result
pH:
9
Temp.:
50 °C
DT50:
> 21 d
Remarks on result:
hydrolytically stable based on preliminary test
Other kinetic parameters:
The rate of hydrolysis was extrapolated to 25°C for pH 4.0 and 7.0 using the Arrhenius equation: k(obs) = Ae-(Ea/RT) or ln k(obs) = Ln A -Ea/RT
Details on results:
t1/2 pH 4: ca. 1 hour(s) at 10 ºC

The rate of hydrolysis was determined to be:
19.64 l/s x l0e5 for pH 4.0 (10ºC),
68.75 l/s x l0e5 for pH 4.0 (20ºC),
0.04 l/s x l0e5 for pH 7.0 (20°C)
0.26 l/s x l0e5 for pH 7.0 (40°C)

There was not a determined rate of hydrolysis for pH 9.0 (50°C) since hydrolysis was less than 10%.

The extrapolated rates of hydrolysis for:

12.44 1s x l0e5 for pH 4.0 (25°C)
6.26 l/s x l0e5 for pH 7.0 (25°C)

Therefore, the test substance, n-Butyl glycidyl ether, CAS RN 2426-08-6, underwent rapid hydrolysis at pH 4.0. The rate of hydrolysis slowed down as the pH was increased.
Validity criteria fulfilled:
not specified
Conclusions:
The test substance, n-Butyl glycidyl ether (CAS No. 2426-08-6), underwent rapid hydrolysis at pH 4.0. The rate of hydrolysis slowed down as the pH was increased.
Executive summary:

In the course of a OECD 111 study butyl glycidyl ether has been assessed to be readily and moderately hydrolysable at pH 4 and 7 (with half-times of 0.3 hours and 20.3 days, respectively). At pH 9 and 50 °C no remarkable hydrolysis rate has been determined, as the hydrolysis rate was less than 10 % under these conditions.

Endpoint:
hydrolysis
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Justification for type of information:
There is no study available elucidating the hydrolytic stability of the target substance tert-butyl glycidyl ether. Therefore, a hydrolysis study conducted with glycidyl methacrylate was used in a read-across approach.

This read-across is based on the hypothesis that source and target substances have similar physico-chemical properties because:
- of structural similarity of the target and the source substances (the presence of the identical functional group (2,3-epoxypropyl ether)
- similarity in physico-chemical profile of the source and target substances (MW, water solubility, partitioning behaviour (log Kow value)).
Reason / purpose:
read-across source
Transformation products:
not specified
Key result
pH:
4
Temp.:
25 °C
DT50:
2.83 d
Key result
pH:
7
Temp.:
25 °C
DT50:
3.66 d
Key result
pH:
9
Temp.:
25 °C
DT50:
2.22 d
Conclusions:
The substance is readily hydrolysable.
Executive summary:

In the course of a OECD 111 study glycidyl methacrylate has been assessed to be readily hydrolysable (with T1/2 = 2.83, 3.66 and 2.22 day at pH 4,7,and 9, respectively).

Description of key information

There is no study available elucidating the hydrolytic stability of the target substance tert-butyl glycidyl ether. Therefore, for the determination of the hydrolysis rate the substances 2,3-epoxypropyl methacrylate (EC No. 203-441-9) and n-butyl glycidyl ether (EC No. 219-376-4) are considered as appropriate read-across partners.

This read-across is based on the hypothesis that source and target substances have similar physico-chemical properties, triggered mainly due to similar physico-chemical properties (MW, water solubility, partitioning behaviour (log Kow value) and the presence of the same reactive functional group (2,3-epoxypropyl ether group).

Since n-BGE and tBGE are substances with the same molecular weight (which differentiate only in the structure of the butyl-group), the determined hydrolysis rate for nBGE will therefore be used as a comparative value for the determination of the same value for tBGE.

Consequently, the half-life of tBGE is estimated to 20.3 d (at pH 7 and 20°C).

Key value for chemical safety assessment

Half-life for hydrolysis:
20.3 d
at the temperature of:
20 °C

Additional information