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  OBSH is solid (crystalline) at room temperature. The melting point of OBSH could not be determined as OBSH decomposes at 155°C and above. The density of OBSH was reported as 1.52 g/cm3. The particle size distribution of OBSH ranges between 14 and 17 microns when measured by coulter. The vapor pressure of OBSH could not be determined since the concentration in a trapping solution was below the detection limit. The limit value of 0.00000543 hPa was calculated based on the detection limit of HPLC. OBSH can therefore not be considered volatile.
  The LogKow for OBSH was 0.08 when estimated by OECD QSAR Toolbox. Based on this, OBSH will mainly partition to the water phase. The water solubility was measured to 62.5 mg/l (obtained by OECD 105) and it can be concluded that OBSH is slightly soluble (0.1-100 mg/L).

Explosives, organic peroxides, self-reactive substances and mixtures as well as pyrophoric or oxidising solids should not be considered for classification as flammable solids because flammability is an intrinsic hazard to these classes. Therefore, the classification criteria of flammable solids do not need to be applied to self-reactive substances.

OBSH was found to be explosive when shock treated by fall hammer. The explosivity was inversely related to purity, so OBSH with a purity of 91 to 97% is sensitive to shock, whereas no explosivity is observed for purities below 90%, neither when treated with shock, friction nor flame source.
OBSH has chemical groups present in the molecule which are associated with explosive or self-reactive properties according to the screening procedures provided in Appendix 6 of the UN-MTC (Tables A6.1 and A6.3). The oxygen balance (-116) identifies the substance as a potential explosive, as it is greater than the limit value of -200.

Self-reactive substances
4,4'-oxydi(benzenesulphonohydrazide) is a compound of the type of aromatic sulfohydrazides (-SO2-NH-NH2) which are known as self-reactive substances (according to section 2.8.1 of the CLP Guidance document (2017)).
Furthermore, the substance is explosive according to EEC Method A.14.
According to the adopted RAC opinion on harmonized classification of OBSH and unpublished test data of UN Test Series A to H in Part II of the UN RTDG, the substance is classified as self-reactive substance of Type D.