(Z)-1,3-dichloropropene

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 April to 27 May 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

hydrolysis measured at pH 5,7 and 9 instead of 4,7, and 9.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

(Z)-1,3-dichloropropene

EC Number:

233-195-8

EC Name:

(Z)-1,3-dichloropropene

Cas Number:

10061-01-5

Molecular formula:

C3H4Cl2

IUPAC Name:

1,3-dichloroprop-1-ene

Details on test material:

Batch number HC2116288B of purity 98.9 %

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

Sampling was performed after a short incubation period and then periodically over the next 17 days in order to obtain regularly spaced data points between 20 and 70% hydrolysis.

Triplicate samples were initially prepared for each buffer system - two were for analysis at each timepoint and were maintained sealed throughout the testing to ensure that the test substance was not lost due to volatility. The third vial was prepared so that the pH of each system could be monitored at each timepoint. Further sets of replicate samples were also prepared 4 days later to allow for sampling timepoints which normally would have coincided with the weekend.

At each sampling point, portions (approximately 100 µL) of the test solutions were removed and diluted with methyl tert-butyl ether to a volume of 10 mL, and dried with anhydrous sodium sulphate. The resulting solutions were analysed by gas chromatography (GC).

Buffers:

PREPARATION OF BUFFER SOLUTIONS

Buffer solutions were prepared using the following volumes:

pH 5.0: Disodium hydrogen orthophosphate dodecahydrate (13.8 g) and citric acid monohydrate (6.45 g) were dissolved in purified water (950 mL) and the pH was adjusted to 5.0 ± 0.05 with 1M sodium hydroxide. The volume was adjusted to 1000 mL with purified water.
Measured pH = 5.00.

pH 7.0 Disodium hydrogen orthophosphate dodecahydrate (12.6 g) and 1M sodium hydroxide (15 mL) were dissolved in purified water (950 mL), and the pH was adjusted to 7.0 ± 0.05 with 1M hydrochloric acid. The volume was adjusted to 1000 mL with purified water.
Measured pH = 7.00.

pH 9.0 Disodium tetraborate decahydrate (16.6 g) and potassium dihydrogen orthophosphate (1.82 g) were dissolved in purified water (950 mL) and the pH was adjusted to 9.0 ± 0.05 with 1M hydrochloric acid. The volume was adjusted to 1000 mL with purified water.
Measured pH = 9.00.

The samples of the buffer solutions were autoclaved prior to use.

Estimation method (if used):

NDA

Details on test conditions:

PROCEDURE
Aliquots (20 mL) of each buffer solution were measured into glass bottles, purged with nitrogen, sealed and placed in a thermostatically controlled water bath at 20°C in the dark. When the buffer solutions had equilibrated at the test temperature, 1,3-D (cis isomer) (18 µL) was added to each sample to give a nominal concentration of approximately 1.1 g/L. The bottles were transferred back to the water bath and held in the dark until sampling was required. Sampling was performed after a short incubation period and then periodically over the next 17 days in order to obtain regularly spaced data points between 20 and 70% hydrolysis.

The temperature of the bath was monitored over the period of the test. It was noted that the bath was at 20 ± 1°C for the duration of testing, with the exception that the temperature fell to freezing for a short period after 10 days due to a power failure. The drop in temperature did not appear to affect the results for the study.

Duration of test

Duration:

410 min

Temp.:

20

Initial conc. measured:

>= 0.909 - <= 0.978 g/L

Number of replicates:

2

Positive controls:

not specified

Negative controls:

not specified

Statistical methods:

NDA

Results and discussion

Preliminary study:

NDA

Test performance:

NDA

Transformation products:

not measured

Details on hydrolysis and appearance of transformation product(s):

The test substance, 1,3-D (cis isomer) was shown to hydrolyse primarily to cis-3-chloroallyl alcohol and the reaction was believed to occur via a nucleophilic substitution mechanism. This mechanism is known to be independent of pH, as confirmed by the fact that the hydrolytic rate constants were observed to be approximately equal at pH 5, 7 and 9.

On quantifying the levels of 1,3-D (cis isomer) and cis-3-chloroallyl alcohol present in samples which had undergone hydrolysis, the results indicated that greater than 90% of the parent molecule was accounted for.

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

Key result

pH:

9

Temp.:

20 °C

Hydrolysis rate constant:

0.003

DT50:

211 h

Type:

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

Dissipation DT50 of parent compound 2

Key result

pH:

7

Temp.:

20 °C

Hydrolysis rate constant:

0.003 h-1

DT50:

232 h

Type:

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

Dissipation DT50 of parent compound 3

Key result

pH:

5

Temp.:

20 °C

Hydrolysis rate constant:

0.003 h-1

DT50:

202 h

Type:

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

Other kinetic parameters:

NDA

Details on results:

There was a decrease in pH of the buffer solutions with time. This observation is consistent with the hydrolysis of a chlorinated molecule via a nucleophilic substitution reaction with the formation of hydrochloric acid and the corresponding alcohol.

From the analysis of the cis-3-chloroallyl alcohol reference material it was possible to confirm that the compound was the principal byproduct of the hydrolysis reaction.

At each pH, the results indicated that on average greater than 90% of the parent molecule was accounted for during the hydrolysis study.

Any other information on results incl. tables

The following rate constants and half-lives were determined:

pH	Rate Constant  (hours^-1)	Half-Life (hours)
5	0.00343	202
7	0.00299	232
9	0.00328	211

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The test substance, 1,3-D (cis isomer) was shown to hydrolyse primarily to cis-3-chloroallyl alcohol and the reaction was believed to occur via a nucleophilic substitution mechanism. This mechanism is known to be independent of pH, as confirmed by the fact that the hydrolytic rate constants were observed to be approximately equal at pH 5, 7 and 9.

On quantifying the levels of 1,3-D (cis isomer) and cis-3-chloroallyl alcohol present in samples which had undergone hydrolysis, the results indicated that greater than 90% of the parent molecule was accounted for.

Executive summary:

The test substance, 1,3-D (cis isomer) was shown to hydrolyse primarily to cis-3-chloroallyl alcohol and the reaction was believed to occur via a nucleophilic substitution mechanism. This mechanism is known to be independent of pH, as confirmed by the fact that the hydrolytic rate constants were observed to be approximately equal at pH 5, 7 and 9.

On quantifying the levels of 1,3-D (cis isomer) and cis-3-chloroallyl alcohol present in samples which had undergone hydrolysis, the results indicated that greater than 90% of the parent molecule was accounted for.