The solubilities of 2-carboxyethylphenylphosphinic acid (CEPPA) and a potential reactive flame retardant, 4-carboxyphenylphenylphosphinic acid (CPPPA), in water were measured. The concentration of the solution was determined by sodium hydroxide titration with phenolphthalein as the indicator. The solubilities of CEPPA were measured from 25.10 °C to 76.32 °C with an uncertainty of 2.2%, and the solubilities of CPPPA were measured from 26.70 °C to 94.52 °C with an uncertainty of 2.1%.

The density of phenylphosphonic dichloride (C6H5POCl2) over a temperature range from 293.17 K to 342.85 K and viscosity over a temperature range from 293.21 K to 341.85 K were measured. The vapor pressure of phenylphosphorus dichloride (C6H5PCl2) and phenylphosphonic dichloride in the ranges from 349.26 K to 426.06 K and from 377.15 K to 457.65 K, respectively, were measured by a static method. The density data were fitted to a second-order polynomial, and the viscosity data were fitted to the Andrade equation. The results of vapor pressure of phenylphosphorus dichloride and phenylphosphonic dichloride were fitted to the Antoine equation. The density data of phenylphosphonic dichloride and vapor pressure data of phenylphosphorus dichloride and phenylphosphonic dichloride were compared with literature values.