2,6-dimethyl-4-(2,2,3-trimethylcyclopent-3-en-1-yl)cyclohex-2-en-1-ol

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

October 2nd, 2019

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
iSafeRat® toolbox – in Silico Algorithms For Environmental Risk And Toxicity version 2.4

2. MODEL (incl. version number)
iSafeRat® vapour pressure HA-QSAR v1.3

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CC1CC(C=C(C1O)C)C2CC=C(C2(C)C)C

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF

5. APPLICABILITY DOMAIN
See attached QPRF

6. ADEQUACY OF THE RESULT
See attached QPRF

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

not applicable

Remarks:

QSAR model

Principles of method if other than guideline:

The purpose of the in silico study was to determine the vapour pressure of the test item. The determination was performed using a regression method in which validated boiling point values are plotted against the log of vapour pressure values, where the pressure is in Pascals. The comparison was made with other members of the same chemical group. The results are considered to be as accurate as those from a good quality OECD guideline 104 study.

GLP compliance:

no

Type of method:

other: QSAR model

Key result

Temp.:

25 °C

Vapour pressure:

0.112 Pa

95% confidence interval (α = 0.05): 0.081 – 0.155 Pa

Statistical characteristics of the model are given in the QMRF report.

Applicability domains of the model have been verified:

Descriptor domain:

As described in the relevant QMRF report, the applicability domain of the iSafeRat® HA-QSAR module for vapour pressure was based on k-Nearest Neighbours approach taking into account 5 closest training neighbours (k=5). The boiling point value for the test substance (BP = 305.9°C) used as the descriptor for this prediction falls outside the applicability domain comprised between 82.3°C and 296.88°C. However, substances with a higher boiling point than 296.88°C or lower boiling point than 82.3 °C are expected to follow the same tendency as the training set. Therefore, the predicted extrapolated value is considered valid with an accuracy comprised within the reported 95% confidence interval range.

Structural fragment domain:                                                                                                                                         

All chemical groups within the molecular structure are represented within the datasets used by the model.

Mechanism domain:

Vapour pressure of the substance is determined using boiling point as the descriptor. The local model used is depending on the capability of the substance to participate in intermolecular interactions, such as hydrogen bonding. iSafeRat® vapour pressure HA-QSAR v1.3 includes the following local models, ranked by increasing intermolecular attractive interactions:

·       Vapour pressure local model for NonPolar Organic compounds:for compounds which can only participate in weak Van der Waals attractive forces (e.g. alkanes, halides, alkenes, thiols…etc.).

·       Vapour pressure local model for Oxygenated, NonHydroxylated compounds:for compounds which can participate in strong Van der Waals attractive forces (e.g. ethers, mono-esters, ketones, aldehydes, epoxides, lactones, carbonates, (meth)acrylates).

·       Vapour pressure local model for Oxygenated, Hydroxylated compounds (Secondary and Tertiary Alcohols and phenols), which can participate in hydrogen bonds.

·       Vapour pressure local model for Oxygenated, Hydroxylated compounds (Primary Alcohols), which can participate in hydrogen bonds.

·       Vapour pressure local model for Carboxylic Acids, which can participate in hydrogen bonds.

Given the molecular structure of the substance (a secondary alcohol), the submodel used to predict its vapour pressure is the one dedicated to Oxygenated, Hydroxylated compounds (Secondary and Tertiary Alcohols and phenols) which are both bond acceptor and donor compounds.

Conclusions:

Low volatility (based on volatility bands criteria for occupational exposure (Chesar / ECETOC TRA), << 500 Pa).

Executive summary:

A validated Quantitative Structure-Property Relationship (QSPR) model was used to calculate the vapour pressure of the test item.

The determination was performed using a regression method in which validated boiling point values are plotted against the log of vapour pressure values, where the pressure is in Pascals.

The experimental boiling point was used as input.

The test item falls within the applicability domains of the model, except for descriptor domain and was therefore predicted by extrapolation for its vapour pressure. The predicted extrapolated value is considered valid with an accuracy comprised within the reported 95% confidence interval range. Therefore, this endpoint value can be considered valid and fit for purpose.

The vapour pressure was determined as 0.112 Pa at 25°C.

95% confidence interval (α = 0.05): 0.081 – 0.115 Pa.

Description of key information

Low volatility (calculated value).

Key value for chemical safety assessment

Vapour pressure:

0.112 Pa

at the temperature of:

25 °C

Additional information

No experimental study was available on the substance.

Therefore, the Vapour Pressure was reliably estimated by a validated QSAR, using the experimental boiling point as input.