Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

Styrene oxide is a colourless, organic liquid at standard conditions (20°C, 1013 hPa). It has a melting point of -35.6°C and a boiling point of 194.1°C. The substance has a density of 1.049 g/cm³ at 25°C.

The vapour pressure of styrene oxide was determined via vapour pressure balance (thermo-gravimetric effusion method; OECD guideline 104 and EU-Method A.4) at temperatures of 30, 35, 40 and 45°C. Based on the experimentally derived results the vapour pressure of 34.9 Pa at 20°C was calculated by extrapolation. Styrene oxide has an n-octanol/water partition coefficient log Kow of 1.61.

The water solubility of styrene oxide was investigated in a study conducted according to OECD Guideline 105 and EU-Method A.6 using the flask method and GC-FID for quantification. It was observed that the test substance concentrations decreased rapidly with the stirring times of 1, 3, 6 and 24 hours. It indicated that the test substance degrades/reacts when dissolved in water. The test was performed with a minimum stirring time of 1 hour. The concentration of this sample is issued as the water solubility of the test substance. The water solubility of styrene oxide was determined to be 1.49 g/L at 20°C, after 1 h of stirring. The pH of the aqueous sample after 1 hour of stirring was 4.6.

The flash point of styrene oxide was investigated in a study conducted according to EU-Method A.9 using the the Pensky-Martens closed cup method. The flash point of styrene oxide was determined to be 74°C at a barometric pressure of 1013 hPa. Styrene oxide has an ignition temperature of 498°C.