Reaction mass of ethyl 2,6,6-trimethylcyclohexa-1,3-diene-1-carboxylate and ethyl 2,6,6-trimethylcyclohexa-2,4-diene-1-carboxylate and ethyl 6,6-dimethyl-2-methylenecyclohex-3-enecarboxylate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Remarks:

as a function of pH

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 November 2020- 04 March 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 20 to 21 November 2018 and 7 June 2019; Date of decision: 21 August 2019

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals/times for pH measurements: 0, 120 and 126 h

Buffers:

pH 4: Ready-made concentrate (Titrisol®, MERCK, Darmstadt, Germany, art. No. 9884, citrate/ hydrochloric acid buffer) pH 4.00 ± 0.02 at 20°C,
pH 7: Ready-made concentrate (Titrisol®, MERCK, Darmstadt, Germany, art. No. 9887, phosphate buffer) pH 7.00 ± 0.02 at 20°C,
pH 9: Ready-made concentrate (Titrisol®, MERCK, Darmstadt, Germany, art. No. 9889, boric acid/ potassium chloride/ sodium hydroxide buffer) pH 9.00 ± 0.02 at 20°C,
In order to avoid any unnecessary excess of inorganic salts that could reduce the solubility of the test substance, these buffer solutions were diluted to 10% with ultrapure water before being used as test media.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: Hydrolysis reactions are performed in amber glass bottles (repeated sampling from recipient) or 20 ml amber-glass vials (crimp caps with Teflon coated rubber septa, a minimum of two vials is sacrificed for each sampling point). A constant temperature water bath (JULABO MP, JULABO Labortechnik GmbH, Seelbach, Germany) is used to maintain to ±0.1 °C the test vessel temperature.
- Sterilisation method: None

Duration:

0 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

71.91 mg/L

Remarks:

Ethyl Safranate is considered hydrolytically stable.

Duration:

0 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

74.24 mg/L

Remarks:

Ethyl Safranate is considered hydrolytically stable.

Duration:

0 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

73.88 mg/L

Remarks:

Ethyl Safranate is considered hydrolytically stable.

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Preliminary study:

The preliminary test (Tier 1) was performed at 50°C and at pH 4, pH 7 and pH 9. The obtained hydrolysis values were 0.82%, 7.12% and 10.54% respectively.

Transformation products:

not specified

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Type:

not specified

pH:

9

Temp.:

25 °C

DT50:

>= 1 yr

Type:

not specified

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Type:

not specified

Table 5.1.2/1. Percentage decrease of test item after 120 h and 126 h of hydrolysis at pH 4, 7 and 9

pH	Percentage decrease of test item
pH 4 at 120h	0.82
pH 7 at 120h	7.13
pH 9 b t 120h	10.54
pH 4 at 126h	2.23
pH 7 at 126h	3.66
pH 9 at 126h	28.00

  

At pH 4 and pH 7, test item is considered hydrolytically stable since, less than 10% hydrolysis occurred after 120 h, which corresponds to a half-life of more than one year at 25°C according to the OECD Guideline 111. Therefore, no additional testing is required at pH4 and pH 7.

At pH 9 the observed hydrolysis in the preliminary test was slightly higher than 10%. However, it was decided not to pursue with the Tier 2 test given that the observed value of 10.54% after 120 h would not represent significant hydrolysis potential or a significant change in the half-life of the substance which was estimated to be approximately 30 days at 50 °C, equivalent to approximately 1 year at 25°C according to the OECD Guideline 111.

Validity criteria fulfilled:

yes

Conclusions:

The half-life time of test item at 25°C is higher than one year at pH 4 and pH 7, while at pH 9 the hydrolysis of test item corresponds to a value of approximately 1 year at 25°C according to the OECD Guideline n° 111.

Executive summary:

An abiotic degradation study (hydrolysis as a function of pH) was carried out with test item according to OECD guideline 111. The preliminary test (Tier 1) was performed at 50°C and at pH 4, pH 7 and pH 9. The obtained hydrolysis values were 0.82%, 7.12% and 10.54% respectively.

At pH 4 and pH 7, test item is considered hydrolytically stable since, less than 10% hydrolysis occurred after 120 h, which corresponds to a half-life of more than one year at 25°C according to the OECD Guideline n° 111. Therefore, no additional testing is required at pH4 and pH 7.

At pH 9 the observed hydrolysis in the preliminary test was slightly higher than 10%. However, it was decided not to pursue with the Tier 2 test given that the observed value of 10.54% after 120 h would not represent significant hydrolysis potential or a significant change in the half-life of the substance which was estimated to be approximately 30 days at 50 °C, equivalent to approximately 1 year at 25°C according to the OECD Guideline 111.

Therefore, the half-life time of test item at 25°C is higher than one year at pH 4 and pH 7, while at pH 9 the hydrolysis of test item corresponds to a value of approximately one year at 25°C according to the OECD Guideline 111.

Description of key information

An abiotic degradation study (hydrolysis as a function of pH) was carried out with test item according to OECD guideline 111. The preliminary test (Tier 1) was performed at 50°C and at pH 4, pH 7 and pH 9. The obtained hydrolysis values were 0.82%, 7.12% and 10.54% respectively.

 

At pH 4 and pH 7, test item is considered hydrolytically stable since, less than 10% hydrolysis occurred after 120 h, which corresponds to a half-life of more than one year at 25°C according to the OECD Guideline n° 111. Therefore, no additional testing is required at pH4 and pH 7.

 

At pH 9 the observed hydrolysis in the preliminary test was slightly higher than 10%. However, it was decided not to pursue with the Tier 2 test given that the observed value of 10.54% after 120 h would not represent significant hydrolysis potential or a significant change in the half-life of the substance which was estimated to be approximately 30 days at 50 °C, equivalent to approximately 1 year at 25°C according to the OECD Guideline 111.

 

Therefore, the half-life time of test item at 25°C is higher than one year at pH 4 and pH 7, while at pH 9 the hydrolysis of test item corresponds to a value of approximately one year at 25°C according to the OECD Guideline 111.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C