(3S-cis)-3,6-dimethyl-1,4-dioxane-2,5-dione

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is readily biodegradable

Reference 2

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Peer-reviewed publication, but very poorly documented (complete lack of documentation of experimental conditions like pH, buffer systems, sterility, etc.), therefore considered as invalid.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Hydrolysis of L-lactide. A 100 or 1000 ppm solution of L-lactide was prepared by diluting a 1 % solution of lactide in acetonitrile with distilled water or 8 % ethanol at the appropriate temperature. Samples were aged at the respective temperatures, removed at various times and analysed directly by gas chromatography (GC).

GLP compliance:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): L-lactide
- Substance type: Organic

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Directly analysed by GC.

Duration:

30 min

Temp.:

80 °C

Initial conc. measured:

ca. 100 other: ppm

Duration:

90 min

Temp.:

60 °C

Initial conc. measured:

ca. 100 other: ppm

Duration:

180 min

Temp.:

21 °C

Initial conc. measured:

ca. 100 other: ppm

Transformation products:

not measured

Temp.:

21 °C

Hydrolysis rate constant:

ca. 0.23 h-1

DT50:

ca. 3 h

Type:

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

Validity criteria fulfilled:

no

Conclusions:

At 21 °C a hydrolysis half-life of 3 h (k = 0.23 h^-1) was determinded for L-lactide. The expermiments are, however, very poorly documented, not allowing an assessment of reliability. The study is considered to be invalid.

Executive summary:

Hydrolyis experiments with L-lactide are reported in a published paper, but methods and results are very poorly documented. Analytical methods, employed pH, buffers (if relevant), sterility of equipment, initial and measured concentrations, or any other crucial conditions, were not reported. The study is thus considered to be unreliable.

The half-life of L-lactide in water at 21 °C was determined to be 3 h, corresponding to a rate constant of 0.23 h^–1.

Description of key information

According to Annex VIII, point 9.2.2.1, column 2 of the REACH Regulation, a hydrolysis study does not need to be conducted if the substance is readily biodegradable or highly insoluble in water. LL-lactide is predicted to be readily biodegradable hence a hydrolysis study is not considered to be required.