Registration Dossier
Registration Dossier
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EC number: 200-238-7 | CAS number: 55-56-1
Endpoint summary
Administrative data
Description of key information
Additional information
Chlorhexidine base is a white solid. According to handbook data, the melting point is 134°C. A model calculation predict a boiling point of 693.68°C. However, it is expected that chlorhexidine base will decompose before boiling, based on the results of Chlorhexidine salts.
According to a peer-reviewed database, the density was estimated to be 1.39 g/cm3.
The vapour pressure was calculated to be 2.92E-14 hPa at 25°C.
According to two peer-reviewed databases, the water solubility of chlorhexidine base is 6 mg/L and 800 mg/L, both at 20°C. The pH value is not reported. However, water solubility is expected to be strongly dependent on pH. In a potentiometric titration study the pKa of Chlorhexidine base was determined to be 10.78. A model calculation resulted in pKa values of 11.41, 12.02, 2 -4 and <0. This calculated values clearly indicate an complete dissociation in aqueous solutions in the ecological interesting pH range. Thus, the undissociated form of Chlorhexidine only exists at high pH values.
In a model calculation the octanol/water partition coefficient of Chlorhexidine base was predicted to be 1.58 in the pH range from 4 to 8. The log POW is expected to increase with increasing pH.
There are no data about surface tension of Chlorhexidine base available. However, the surface tension of Chlorhexidine digluconate was determined to ca. 50 mN/m at a concentration of 0.59 % in water. Therefore, also Chlorhexidine base is expected to have surface-active properties.
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