2-Propenoic acid, 2-[2-(ethenyloxy)ethoxy]ethyl ester

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 February 2009 to 5 March 2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The non-GLP study meets generally accepted scientific standards, is well documented and acceptable for assessment.

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

GLP compliance:

no

Remarks:

In-house study not conducted to GLP

Radiolabelling:

no

Analytical monitoring:

yes

Buffers:

Test System:
- A sterile buffer pH4: Potassium hydrogen phthalate aqueous solution
- A sterile buffer pH7: Potassium dihydrogen phosphate aqueous solution
- A sterile buffer PH9: Sodium tetraborate aqueous solution

Reagents:
- pH 4 buffer solution: Wako Pure Chemical Industries, Inc. Buffer Solution Standard (#028-03185), Japan
- pH 7 buffer solution: Wako Pure Chemical Industries, Inc. Buffer Solution Standard (#025-03195), Japan
- pH 9 buffer solution: Wako Pure Chemical Industries, Inc. Buffer Solution Standard (#028-03205), Japan
- Ethylene glycol: >99%, Wako Pure Chemical Industries, Inc., Japan

Details on test conditions:

TEST SYSTEM
- Lighting: No
- Measures taken to avoid photolytic effects: Test conducted in darkness

Duration:

2 h

pH:

4

Temp.:

30 °C

Initial conc. measured:

876.9 mg/L

Duration:

1 h

pH:

4

Temp.:

40 °C

Initial conc. measured:

874.8 mg/L

Duration:

132 h

pH:

7

Temp.:

30 °C

Initial conc. measured:

971 mg/L

Duration:

72 h

pH:

7

Temp.:

40 °C

Initial conc. measured:

928 mg/L

Duration:

40 h

pH:

9

Temp.:

30 °C

Initial conc. measured:

952.9 mg/L

Duration:

18 h

pH:

9

Temp.:

40 °C

Initial conc. measured:

916.7 mg/L

Number of replicates:

1

Positive controls:

no

Negative controls:

no

Statistical methods:

The logarithms of all relative concentrations were plotted against time and a linear regression program (least-squares method) was used to calculate the regression line.

Preliminary study:

For testing of pseudo-first order kinetics (Test 1 according to EEC guideline C.7) at pH7 and pH9, the logarithms of the relative concentrations between 80 % and 30 % (i.e. between 20 % and 70 % hydrolysis) were plotted against time. Because at both pHs linear relationships were found, the reactions were considered to be (pseudo)-first order. Hence, the half-life times at 25 °C were estimated in a subsequent test.

Test performance:

The coefficients of determination (R²) were between 0.9995 and 0.9841, which confirmed the satisfying linearity of the results.

Transformation products:

not measured

pH:

4

Temp.:

40 °C

Hydrolysis rate constant:

1.174 h-1

DT50:

0.59 h

pH:

4

Temp.:

30 °C

Hydrolysis rate constant:

0.563 h-1

DT50:

1.231 h

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

0.382 h-1

DT50:

1.81 h

Remarks on result:

other: the rate constant (and the corresponding half-life time) at 25 °C was calculated using the Arrhenius equation

pH:

7

Temp.:

40 °C

Hydrolysis rate constant:

0.016 h-1

DT50:

42.2 h

pH:

7

Temp.:

30 °C

Hydrolysis rate constant:

0.006 h-1

DT50:

116.92 h

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

0.003 h-1

DT50:

200.1 h

Remarks on result:

other: the rate constant (and the corresponding half-life time) at 25 °C was calculated using the Arrhenius equation

pH:

9

Temp.:

40 °C

Hydrolysis rate constant:

0.05 h-1

DT50:

14 h

pH:

9

Temp.:

30 °C

Hydrolysis rate constant:

0.018 h-1

DT50:

39.02 h

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0.01 h-1

DT50:

66.88 h

Remarks on result:

other: the rate constant (and the corresponding half-life time) at 25 °C was calculated using the Arrhenius equation

- The actual temperature during the tests was measured in the 40 °C treatments and found to be 40.0 ± 0.5 °C

- No test substance was detected in the blank buffer solutions

Results of hydrolysis tests at pH 4, pH 7 and pH 9

Code pH and temperature	Measured pH value	Time [hours]	Concentration test substance [mg/L]	Relative concentration [%]	Logarithm relative concentration
pH 4- 30 °C	4.01	0	876.9	100	2.00
		0.5	679.8	77.5	1.89
		0.67	608.7	69.4	1.74
		0.83	549.6	62.7	1.70
		1	504.7	57.6	1.76
		1.17	456.4	52.0	1.72
		1.33	417.9	47.7	1.68
		1.67	346.0	39.5	1.60
	4.01	2	287.0	32.7	1.51
pH 4- 40 °C	4.02	0	874.8	100	2.00
		0.25	688.9	78.8	1.90
		0.33	636.8	72.8	1.86
		0.5	538.1	61.5	1.79
		0.67	419.0	47.9	1.68
		0.83	312.8	35.8	1.55
	4.01	1	292.3	33.4	1.52
pH 7- 30 °C	6.88	0	971.0	100	2.00
		48	727.6	74.9	1.87
		61	677.7	69.8	1.84
		65	651.1	67.1	1.83
		69.5	652.5	67.2	1.83
		84	592.8	61.1	1.79
		89	582.3	60.0	1.78
		94	559.1	57.6	1.76
		108	507.5	52.3	1.72
		114.5	487.3	50.2	1.70
	6.88	132	446.0	45.9	1.66
pH 7- 40 °C	6.90	0	928.0	100	2.00
		22	666.6	71.8	1.86
		30	578.9	62.4	1.80
		48	415.6	44.8	1.65
		56	381.5	41.1	1.61
		60	350.1	37.7	1.58
	6.89	72	286.8	30.9	1.49
pH 9- 30 °C	9.14	0	952.9	100	2.00
		14.2	718.8	75.4	1.88
		16	714.5	75.0	1.87
		18	674.8	70.8	1.85
		20	662.8	69.6	1.84
		23	627.8	65.9	1.82
	9.15	40	465.6	48.9	1.69
pH 9- 40 °C	9.16	0	916.7	100	2.00
		5	670.3	73.1	1.86
		8	592.1	64.6	1.81
		10	564.2	61.5	1.79
		13	478.5	52.2	1.72
		15	428.3	46.7	1.67
	9.15	18	363.1	39.6	1.60

 

Conclusions:

The hydrolysis of the test substance as a function of pH was assessed according to EU Method C7. The test substance was determined to be hydrolytically unstable (half-life time at 25 °C < 1 day) in aqueous solutions buffered at pH 4. The half-life time of the test substance at 25 °C was 1.81 h in aqueous solutions buffered at pH 4, 200.1 h in aqueous solutions buffered at pH 7 and 66.9 h in aqueous solutions buffered at pH 9.

Executive summary:

The determination of the hydrolysis rate of VEEA as a function of pH was based on the EEC-Directive 92/69 EEC, Part C, Methods for the determination of Ecotoxicity, C.7: "Abiotic degradation: Hydrolysis as a function of pH", EEC Publication no. L383, December 1992.

The test substance is hydrolytically unstable (half-life time at 25 °C < 1 day) in aqueous solutions buffered at pH 4.

The half-life time of test substance at 25 °C was 1.81 hours in aqueous solutions buffered at pH4.

The half-life time of test substance at 25 °C was 200.1 hours in aqueous solutions buffered at pH7.

The half-life time of test substance at 25 °C was 66.9 hours in aqueous solutions buffered at pH9.

Description of key information

Readily hydrolisable, pH dependent, transformation products unknown but readily biodegradable

Key value for chemical safety assessment

Half-life for hydrolysis:

200.1 h

at the temperature of:

25 °C

Additional information

The submission item is hydrolytically instable under environmentally relevant conditions. The degradation half-life peaks around neutral pH 7 (ca. 200 hours) and is lower in acidic (ca. 2 hours at pH 4) or basic media (ca. 67 hours at pH 9). As it is in addition readily biodegradable the identification of hydrolysis products is considered not required and a full hydrolysis study with a radiolabelled test item was therefore not performed.