3-(methylthio)propionaldehyde

Endpoint summary

Additional information

3-(Methylmercapto)propionaldehyde is a colourless, organic liquid with pungent odour. The melting point and boiling point of 3-(methylmercapto)propionaldehyde are determined to be -75 °C and 170.3 °C at 1,013 hPa, respectively. The relative density is 1.036 at 20 °C. According to REACH regulation (Annex VII, 7.14, column II), the study on granulometry does not need to be conducted if the substance is marketed or used in a non solid or non granular form. The vapour pressure at 20 °C was calculated based on the measured values (range: 27 - 82 °C) obtained in a study conducted according to OECD Guideline 104. The calculation yielded a vapour pressure of 0.53 hPa at 20 °C. The n-octanol/water partition coefficient of 3-(methylmercapto) propionaldehyde was found to be 0.35 at 20 °C and pH 7.4 - 7.8 in a study conducted according to OECD Guideline 107. The water solubility is 16.3% (v/v) at 25 °C, corresponding to ca. 170 g/L. MMP is regarded as very soluble in water. According to REACH regulation (Annex VII, 7.6, column II), the surface tension study needs only to be conducted if based on the structure of the substance, surface activity is to be expected or can be predicted or surface activity is a desired property of the material. In a study conducted according to the German DIN 51758 (Pensky-Martens: closed cup), the flash point was determined to be 69 °C. In a study according to ASTM D56 (Tag closed cup) the flash point was determined to be 61.4 °C. In a study conducted according to the German DIN 51794, the auto-ignition temperature was found to be 280 °C. Based on the flash point the substance is not a flammable liquid according to CLP. Based on the chemical structure and experience in handling and use, pyrophoricity and flammability on contact with water are not expected. Liquids do not show self-heating behaviour if they are not absorbed on a large surface. There are no chemical groups associated with explosive or self-reactive properties present in the molecule, therefore according to CLP regulation MMP is not an explosive and not a self-reactive substance. On the basis of the chemical structure the substance is incapable of reacting exothermically with combustible materials, therefore it is not an oxidising substance according to CLP. MMP showed a strong exothermal behaviour above 30 °C in a hot storage test. The stability assessment demonstrated stable storage conditions up to 60 °C. 1:1 MMP/acrolein mixtures containing catalyst exhibited no exothermal behaviour at 13 °C - 119 °C. The substance does not contain acidic or basic groups, it does not contain halogen and is not a complexing agent. In an immersion test the substance shows corrosivity towards unalloyed steel, however the corrosion rate is far below 6.25 mm/a even at 65 °C for 455 h. Furthermore, from experience in handling and use for over 30 years a manufacturer never observed any corrosion issues. Therefore, it is concluded that the substance does not need to be considered for classification as metal corrosive according to CLP.