3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-indenyl propionate

Hydrolysis

Description of key information

For Cyclaprop the estimated half-life for hydrolysis is > 1 year for pH 4 and 7; for pH 9 the half life is 13 days based on information from Cyclobutanate which was tested in an OECD TG 111 study.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

For Cyclaprop no experimental hydrolysis information is available. This information can be retrieved from Cyclobutanate using read across. First the experimental information of Cyclobutanate is presented and thereafter the read across justification to use this information for Cyclaprop.

Cyclobutanate experimental hydrolysis information

For assessing hydrolysis of Cyclobutanate a test according to OECD TG 111 was performed with the following results. At pH 4 and 7 the estimated half-lives at 25°C are > 1 year. At pH 9 at 25°C the estimated half-life is 13 days.

Cyclaprop and its hydrolysis as function of pH using read across information from Cyclobutanate

Introduction and hypothesis for the analogue approach

Cyclaprop is a propionic ester attached to a tricyclodecenyl fused ring structure. For this substance no experimental hydrolysis data is available. In accordance with Article 13 of REACH where is presented that lacking information can be generated by means other than experimental testing such as SARs, grouping and read-across, the data gap of Cyclaprop is filled by using read across from the analogue Cyclobutanate.

Hypothesis: Cyclaprop has the same hydrolysis properties as its analogue Cyclobutanate because it is hypothesised that one methyl group difference in the alkyl chain does not affect the hydrolysis rate.

Available experimental information: For Cyclobutanate a well conducted hydrolysis test (OECD TG 111, Klimisch 1) is available. The obtained data showed that the estimated half-life for hydrolysis is > 1 year for pH 4 and 7, and for pH 9 the half-life is 13 days.

Target chemical and source chemical(s)

Chemical structures of the target chemical Cyclaprop and the source chemical Cyclobutanate are shown in the data matrix, including relevant physico-chemical properties.

Purity / Impurities

Cyclaprop is a reaction masses containing a mixture of two very similar isomers (5-yl and 6-yl). The impurities are all below 1%.

Analogue approach justification

According to Annex XI 1.5 read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation, which is presented below.

Analogue justification: For Cyclaprop the analogue Cyclobutanate is selected based on similarity in chemical structure and because for Cyclobutanate hydrolysis information is available.

Structural similarities and differences: The target and the source chemical both have a tricyclodecenyl fused ring structure with an unsaturated bond in the outside ring, which can be on the 5yl or 6 yl position. On the other side of the ring an ester bond is attached with a short alkyl chain. The alkyl chain of Cyclaprop is a propyl chain while the source Cyclobutanate has a butyl chain. This means that the only difference between the two is that Cyclaprop has a one methyl group shorter alkyl chain.

Hydrolysis reactivity: The propionic ester of Cyclaprop versus the butyric ester group of Cyclobutanate is expected to be similarly (in)sensitive to hydrolysis. The protrusive positive charge of the methyl groups towards the ester bond may be slightly lower for Cyclaprop compared to Cyclobutanate but this will be minimal and therefore not affect the hydrolysis potential.

Uncertainty of the prediction: There or no remaining uncertainties other than those already addressed above.

Conclusions on the hydrolysis of Cyclaprop

For Cyclaprop no hydrolysis information is available. For Cyclobutanate, a related analogue, such information is present, which can be used for read-across. When using read across the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation. The current document fulfils this documentation.The estimated Cyclobutanate half-life for hydrolysis is > 1 year at pH 4 and 7 and 13 days at pH 9. As the one methyl will not influence the hydrolysis, the same values can be used for Cyclaprop.

Final conclusion: For Cyclaprop the estimated half-life for hydrolysis is > 1 year for pH 4 and 7 and for pH 9 the half-life is 13 days

Data matrix to support the read across to Cyclaprop from Cyclobutanate on hydrolysis

Common names	Cyclaprop Target	Cyclobutanate Key source
Chemical structures
Cas no 5-yl Cas no of the generic	- 68912-13-0	1361017-07-3 113889-23-9
Empirical formula	C13H18O2	C14H20O2
EINECS	272-805-7	441-420-8
REACH registered	Registered	Registered
Molecular weight	206	220
Physico-chemical data
Physical state	liquid	liquid
Melting point (°C)	< -20	< -20
Boiling point (°C)	263	275
Water solubility (mg/l)	57	11.5
Log Kow	4.4 (HPLC, OECD TG 117)	4.48 (Shake-flask, OECD TG 107)
Environmental Fate
Hydrolysis	RA Cyclobutanate	Half-life: pH 4: > 1 year pH 7: > 1 year pH 9: 13 days