1,3-diphenylguanidine

Water solubility

Description of key information

The water solubility of DPG (1,3-diphenylguanidine) was evaluated in a study performed in accordance with OECD testing guideline 105 and GLP requirements. The flask method was used. The water solubility has been calculated as the mean value from at least five consecutive samples taken from the saturation plateau. Water solubility of DPG was determined as being 325 mg/L at 20°C and pH = 10.32.

Key value for chemical safety assessment

Water solubility:

325 mg/L

at the temperature of:

20 °C

Additional information

The different records are put into order in the same way as the endpoints study records.

Companies' data

- The water solubility of DPG was evaluated in a study. The NF T 20-046 method (similar to OECD 105, flask method) was used, instead of NF T 20-045 method, although 1,3-diphenylguanidine was supposed to be slightly soluble. The water solubility of DPG was estimated at 475 mg/l (20°C, pH=7). DPG is slightly soluble in water at pH 7 and basic pH (11). At acid pH, DPG is transformed into protonated DPG which is very soluble in water. The results of this method are of acceptable scientific quality and are derived from experimental methodology routinely employed in industrial production at the MLPC plant. Nevertheless the original reference was not found and insufficient information was available.

- The water solubility of DPG was evaluated in another study. No information is given concerning the method that was used. The water solubility of DPG was estimated at 217 mg/l (30°C, pH=10). DPG is moderately soluble in water at pH 10.

- Last, the water solubility of DPG was evaluated in a study. Very few information is given concerning the method that was used. The water solubility of DPG was estimated at 860 mg/l (20°C, pH=7) and 1470 mg/l (25°C, pH = 9). Based on these values DPG is moderately soluble in water at pH = 7 and soluble in water at pH = 9. This result is in opposition with the other two aforementioned data because solubility increases with pH.

Public data

- The water solubility of DPG was recorded in a first publication. Nevertheless, no information is given concerning the method that was used. The water solubility of DPG was estimated at 519 g/l, 43,28 g/l, 22 g/l and 1.5 g/l at 20°C. Details are scarce and the solubility values should be used with care. Routine studies at low pH are not performed at the production sites. Based upon these values and as for the companies' data it can be concluded that strongly acid conditions increase  water solubility of DPG.

- The water solubility of DPG was also recorded in a data review. Again, no information is given concerning the method that was used. The water solubility of DPG was estimated at 1 g/l (25°C). DPG can be considered as moderately soluble in water at 25°C. Concerning pH, no information is clearly given in the document.

- The water solubility of DPG was lastly recorded in another publication. No information is given concerning the method that was used. The water solubility of DPG was estimated to be < 1 g/l at 25°C. Details are scarce and the solubility values should be used with care. Moreover no indication is given on the pH at which the determination was done.

As a conclusion, and in order to have relevant data for water solubility with pH and temperature conditions, a last test was performed according to OECD 105 (flask method). The water solubility has been calculated as the mean value from at least five consecutive samples taken from the saturation plateau. Water solubility was determined as being 325 mg/L at 20°C and pH = 10.32.