2-tert-pentylcyclohexyl acetate

Hydrolysis

Description of key information

The hydrolytical half-life of Coniferan is based on read-across from the close structural analogues Verdox (CAS# 20298-69-5): The DT50 is ca 2 days.

Key value for chemical safety assessment

Half-life for hydrolysis:

2 d

at the temperature of:

25 °C

Additional information

Coniferan's hydrolysis is assessed by using the information from the analogue Verdox. For this substance data are available from an OECD TG 111 study in compliance with the principles of GLP. From this study, the rate of degradation of the test substance at 20 °C and 25 °C was similar at pH 4, 7, and 9 and ranged within 42 - 49 hours (ca. 2 days). 

Hydrolysis of Coniferan (CAS #67874-72-0) using read across from data available from Verdox (CAS #20298-69-5).

Introduction and hypothesis for the analogue approach

Coniferan is an acetate-ester attached to a cyclohexyl ring with a tert-pentyl-group attached atthe ortho-position.For assessment of the hydrolysis potential of Coniferan read-across is performed to the close structural analogue Verdox.

Hypothesis: Coniferan hydrolysis similarly as Verdox because of the similarity in structure and only one methyl group difference. 

Available information: No hydrolysis data are available for the target chemical Coniferan. For the source chemical Verdox data are available from an OECD TG 111 study in compliance with the principles of GLP (K2, because the results may be impacted by the volatility of the substance).

Target chemical and source chemical s

Chemical structures and physico-chemical properties of the target chemical and the source chemical are shown in the data matrix.

Purity / Impurities

Coniferan consists of acis- and trans- variant of the molecule. As its purity is close to 100%, there are no impurities that are expected to significantly affect hydrolysis.Verdox is a comparable substance i.e. a high purity substance consisting of two stereo isomers.

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.

In accordance with RAAF (ECHA, 2017) the selection of analogues is justified. Verdox is considered the closest analogue due to only one methyl group difference in the tert-butyl group at the ortho-position for which hydrolysis information is available.

Structural similarities and differences in relation to the available experimental data:

Coniferan and Verdox show very close structural resemblance. There is only one methyl group difference.

Hydrolysis: For hydrolysis the impact of the structural differences are very limited. Verdox hydrolysed in ca 2 day. The hydrolysis information of Verdox may be due to disappearance of the substance from the test system due to the volatile nature of the substance because similar esters are fairly stable at environmental conditions.

Bioavailability:Coniferan and Verdox are sufficiently water soluble to be hydrolysed.

Hydrolysis: Coniferan and Verdox will be hydrolysed as presented below

Fig. 1 The hydrolysis of esters Coniferan and Verdox. For Coniferan the D-group is a tert-pentyl group, for Verdox this is a tert-butyl group

Uncertainty of the prediction:There is limited uncertainty considering structural and physico-chemical resemblance between the target and source substances. The hydrocarbon backbones are sufficiently alike and the key parameter is the presence of the short-alkyl chain ester group. Using the ECHA guidance (2017, RAAF) criteria for the quality of the read across the score would be 5, based on the reasoning above.

Data matrix

The relevant information on physico-chemical properties and other environmental fate properties are presented in the Data Matrix below.

Conclusions for environmental fate and risk characterisation.

Thehydrolysisinformation from Verdox indicates a degradation of < 2 days, though similar esters are generally fairly stable at environmental pH.

Result for the risk characterisation: Coniferan is expected to hydrolyse within two days.

 

Data matrix for read across for Coniferan from Verdox

Common names	Coniferan	Verdox
Chemical name	2-tert-pentylcyclohexyl acetate	cis-2-tert-butylcyclohexyl acetate
Chemical structures
CAS No.	67874-72-0	20298-69-5
EC No.	Registration 2018	243-718-1 (registered)
Empirical formula	C13H24O2	C12H22O2
Molecular weight	212.3	198.3
Physical state	liquid	Liquidat 30°C
Phys-chem properties
Melting point,^oC	-20	29.8
Boiling point,^oC	252	232
Vapour pressure, Pa	4.24       (at 24 °C)	9.72       (at 23 °C)
Water solubility, mg/L	7.6         (at 24 °C)	10          (at 23 °C)
Log Kow	5.4	4.75
Environmental Fate
Hydrolysis	Read across from Verdox	DT50 = 42-49 hours
Henry coefficient in Pa.mol/m3 at 25oC	118	119