Ethyl 3-[[bis(1-methylethoxy)phosphinothioyl]thio]propionate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014

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 (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

After defined time intervals aliquots of the test solutions were injected into the HPLC system. For calculation the peak area of the main peak was used.

Buffers:

pH 4: Bernd Kraft, citric acid, sodium chloride, sodium hydroxide
pH 7: Bernd Kraft; phosphate mixture
pH9: Bernd Kraft, boric acid, potassium chloride, sodium hydroxide

Estimation method (if used):

Assuming first order reactions, hydrolysis rates and half-lives for other temperatures can be calculated at pH4, pH 7 and pH 9 according to Arrhenius equation. By plotting the natural logarithm of the rate constant against the reciprocal of the temperature (K), the rate constans and half-lives at 20°C and 25°C were obtained by extrapolation.

Transformation products:

not specified

Key result

pH:

4

Temp.:

20 °C

DT50:

15 269 h

Type:

(pseudo-)first order (= half-life)

pH:

4

Temp.:

25 °C

DT50:

6 548 h

Type:

(pseudo-)first order (= half-life)

Key result

pH:

7

Temp.:

20 °C

DT50:

6 314 h

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

25 °C

DT50:

2 808 h

Type:

(pseudo-)first order (= half-life)

Key result

pH:

9

Temp.:

20 °C

DT50:

108 h

Type:

(pseudo-)first order (= half-life)

pH:

9

Temp.:

25 °C

DT50:

52 h

Type:

(pseudo-)first order (= half-life)

Details on results:

No significant hydrolysis products could be elucidated in any test (ph 4, 7, 9) under the analytical conditions applied. It was observed that additional peaks of the test item besides the main peak differed in the peak areas during the hydrolysis test. But there was no linear correlation observable between the main peak and the additional peaks. The peak at about 2.6 min which can be observed in some tests is also detectable in the blank.

The degradation reaction measured at pH 4, 7, 9 can be assumed to be first or pseudo-first order. Due to this the half-lives for 20°C and 25° can be calculated.

Conclusions:

In contact with water the substance will hydrolyse slowly. The slowest reaction is expected in an acidic environment.

Description of key information

In contact with water the substance will hydrolyse slowly. The slowest reaction is expected in an acidic environment.

Key value for chemical safety assessment

Half-life for hydrolysis:

117 d

at the temperature of:

25 °C

Additional information

The results of a hydrolysis study according to OECD guideline 111 show that the test substance was unstable at higher pH and elevated temperatures.

(70 - 80 °C), resulting in half-lives 74 to 67 hours, respectively. At 25 °C the half-life at pH 4 was 2665 hours and > 1 year at pH values of 7 and 9.

The degradation reaction measured by pH 4, pH 7 and pH 9 can be assumed to be pseudo-first order.

The calculated half-lives for 20°c and 25°C are:

	20°C	25°C
pH4	15269h (636.2d)	6548h (272.8d)
pH7	6314h (236.1d)	2808 h (117d)
pH9	108h (4.5d)	52h (2.2d)

No significant hydrolysis products could be elucidated in any test (pH 4, pH 7 and pH 9) under the analytical conditions applied.