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Vapour pressure

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Description of key information

Vapour pressure (VP) is estimated by limited calculation considering only those constituents present with a measurable VP as contributing to the overall VP of the substnce. 

Key value for chemical safety assessment

Vapour pressure:
0 Pa
at the temperature of:
20 °C

Additional information

Because no reliable data were available to fulfill the vapour pressure (VP) endpoint, a conservative estimation was generated based considering only the probable contribution of the known constituents present. The estimated VP of 4x10 -4 is considered a conservative estimate because more than half the manufactured component is comprised of oligomers with molecular weights > 500 which are expected to have a VP < 1x10 -13 (undectable).

A study performed on the Registration material (Phenol, dodecyl-, branched, sulfurized CAS No. 96152-43-1) was carried out but the results actually disregarded based on inconsistencies of the findings with the outcome predicted by application of Raoult's Law of partial pressures for solutions. In accordance with Raoult's Law, the major species present in the manufactured substance would be expected to contribute on a mass molar basis to overall VP of the manufactured substance. The lowest VP for any species present is 0.011 Pa. Based on the principles of chemistry, the findings in this study cannot be considered representative of the substance. The reliability rating was set to 3 and this study was disregarded for CSA purposes.

Data from the QSAR model EPIWIN (Estimations Programs Interface for Windows), are presented within this dossier as they were previously presented as a part of the SIDS Initial Assessment Report for this category of substances. However, it should be borne in mind that current versions of EPIWIN have not been validated for salts or chemicals that are of variable composition. This substance is a highly complex mixture comprising a number of molecules of varying structure with a distribution of carbon chain lengths with varying numbers of alkyl-phenol rings and sulphur bridging between those alkyl-phenol rings. As such the calculated value presented for the category members is based upon an individual representative structure of the alkylated phenol and not the UVCB substance being registered.

Whilst the results of the EPIWIN predictions for each of the individual structures are anticipated to be highly reliable, those results are not considered to be representative of the values that would be predicted for the substance as a whole. As such the estimated values derived from the EPIWIN models have been disregarded for this submission as they are not considered to add any meaningful information to the data presented.

EPISuite - MPBPWIN version 1.41 estimates the vapour pressure to be 9.67 x 10-26mm Hg at 25°C for the mono-sulfur derivative of the test material.

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