Registration Dossier

Physical & Chemical properties

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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.