3-Methoxy-3-methylbutyl acetate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2005

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)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

PHYSICO-CHEMICAL PROPERTIES
- Vapour pressure: 2.58hPa at 25°C
- Water solubility: 58g/L at 20°C
- log Pow: 1.6 at 25°C
- pKa: no data
- Base or acid catalysis of test material: no data
- Stability of test material at room temperature: no data

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products:
pH 4.0 : two points (at the start and after 5 days)
pH 1.2, pH 7.0, and pH 9.0: six points for test duration (each pH and each temperature)
- Sampling method: 1 mL (transfer pipet)

Buffers:

Buffer Solutions
- pH 1.2: 12.9 mL of 1 mol/L hydrochloric acid and 5.0 mL of 2 mol/L potassuim chloride were determined with purified water to 200 mL of a constant volume.
- pH 4.0: 18.0 mL of 0.1 mol/L sodium hydroxide and 100 mL of 0.1 mol/L potassium dihydrogen citrate were determined with purified water to 200 mL of a constant volume.
- pH 7.0: 148.15 mL of 0.1 mol/L sodium hydroxide and 250 mL of 0.1 mol/L potassium dihydrogen phosphate were determined with purified water to 500 mL of a constant volume.
- pH 9.0: 106.5 mL of 0.1 mol/L sodium hydroxide, 0.1 mol/L potassium chloride, and 250 mL of 0.1 mol/L boric acid were determined with purified water to 500 mL of a constant volume.

Estimation method (if used):

Methods of Calculating Residual Percentage of Test Substance, Rate Constant of Hydrolysis, and Half-Life Period
(1) Method of Calculating Residual Percentage of Test Substance (pH 4.0)
The residual factor of the test substance in the test liquid was calculated on the basis of the following equation.
Residual percentage (%) = C/Ci × 100
Ci : Initial concentration (mg/L) of test substance in test liquid
C : Concentration (mg/L) of test substance in test liquid after five days

(2) Method of Calculating Rate Constant of Hydrolysis and Half-Life Period (pH 7.0, pH9.0, and pH1.2)
The logarithm (log C) of the concentration of the test solution at each time was plotted for time (t) to deteramine a regression equation.
The regression equation can be expressed as : log C=at + b
and slant (a) and intercept (b) were calculated from this equation.

Also, the rate constant of the hydrolysis of the test substance and the half-life period were calculated by using the following equations.
k = -2.303 × a
t1/2 = 0.693/k
k : Rate constant of hydrolysis
t1/2 : Half-life period

In addition, with regard to pH7.0 and pH9.0, the logarithm (log k) of the rate constant of the hydrolysis at each temperature was plotted for the reciprocal number (1/T) of the absolute temperature, and a regression equation was found with the method of least squares. The rate constant of the hydrolysis and the half-life period at a temperature of 25°C were extrapolated and determined by using the regression equation obtained from the method of least squares.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 10 mL-Glass test tube with ground-in plug (covered with an aluminum foil)
- Sterilisation method: 0.22µm filter
- Lighting: Under condition of light shielding
- Measures taken to avoid photolytic effects: no data
- Measures to exclude oxygen: no data

TEST MEDIUM
- Volume used/treatment: 10mL
- Kind and purity of water: purified water
- Renewal of test solution: no
- Identity and concentration of co-solvent: none

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Dissolved oxygen: no data

Duration:

11 h

pH:

1.2

Temp.:

37 °C

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

ca. 971 mg/L

Duration:

238 h

pH:

7

Temp.:

60 °C

Duration:

90 h

pH:

7

Temp.:

70 °C

Duration:

24 h

pH:

7

Temp.:

80 °C

Duration:

10 h

pH:

9

Temp.:

50 °C

Duration:

5 h

pH:

9

Temp.:

60 °C

Duration:

130 min

pH:

9

Temp.:

70 °C

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Transformation products:

not measured

% Recovery:

ca. 96.6

pH:

4

Duration:

ca. 5 d

pH:

4

Temp.:

25 °C

DT50:

>= 1 yr

Key result

pH:

7

Temp.:

25 °C

DT50:

ca. 15 200 h

pH:

9

Temp.:

25 °C

DT50:

ca. 157 h

Details on results:

The test substance was immersed in a test liquid with pH 4.0 at a temperature of 50±0.1°C for five days. After the five days, the residual percentage is 90% or more, and therefore the half-life period at a temperature of 25 °C is regarded as being a year or more.


TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

MAJOR TRANSFORMATION PRODUCTS: no data

INDICATION OF UNSTABLE TRANSFORMATION PRODUCTS: no

PATHWAYS OF HYDROLYSIS
- Description of pathways: no
- Figures of chemical structures attached: No

Table1: Hydrolysis

Test liquid	Initial concentration (mg/L)	Concentration after five days (mg/L)	Residual percentage (%)
			Measured value	Mean value
pH 4.0	971	944	97.3	96.6
		931	95.9

Table2: Rate constant and half-life period

		Rate constant (Hour^-1)	Half-life period (Hour)
pH7.0	60°C	4.64×10^-3	149
	60°C	4.64×10^-3	149
	70°C	1.17×10^-2	59.2
	70°C	1.17×10^-2	59.2
	80°C	4.23×10^-2	16.4
	80°C	4.15×10^-2	16.7
	25°C (extrapolated value)	4.57×10^-5	15200
pH 9.0	50°C	6.92×10^-2	10.0
	50°C	7.05×10^-2	9.83
	60°C	2.23×10^-1	3.11
	60°C	2.23×10 ^-1	3.10
	70°C	4.93×10^-1	1.41
	70°C	4.90×10^-1	1.41
	25°C (extrapolated value)	4.41×10^-3	157
pH 1.2	37°C	7.31×10^-2	9.48
	37°C	7.25×10^-2	9.56

Validity criteria fulfilled:

yes

Conclusions:

The test substance was immersed in a test liquid with pH 4.0 at a temperature of 50±0.1°C for five days. After the five days, the residual percentage is 90% or more, and the test substance is regarded as being stable. The half-lives have been extrapolated at 15200h at pH 7.0 and at 157h at pH 9.0.

Description of key information

The test substance was immersed in a test liquid with pH 4.0 at a temperature of 50±0.1°C for five days. After the five days, the residual percentage is 90% or more, and the test substance is regarded as being stable. The half-lives have been extrapolated at 15200h at pH 7.0 and at 157h at pH 9.0.

Key value for chemical safety assessment

Half-life for hydrolysis:

15 200 h

at the temperature of:

25 °C