Dilithium azelate

Endpoint summary

Additional information

Data on physical properties were obtained from a number of proprietary sources, with the remaining physico-chemical endpoints waived (particle size distribution, flash point, explosive properties, oxidising properties, stability in organic solvents, and viscosity). The use of Klimisch codes (Klimisch et al., 1997) was extended to these sources and a reliability code was assigned. All the studies in this section were GLP compliant and followed OECD and EU methods. Therefore, all the studies used in this section were given a reliability rating of 1. A review of the collated information determined that the substances in the lithium salts of dicarboxylic acids C6-C10 have physico-chemical properties as summarised below. On the basis of the available data, none of the substances would meet the criteria for classification for physical hazards.

Dilithium adipate (C6) is a solid at ambient temperature, with a vapour pressure of <1.3 x 10^-8 Pa at 20°C and <2.9 x 10^-8 Pa at 25°C. Dilithium adipate decomposes at temperatures greater than 250°C so no melting point or boiling point were determined. The substance has a density of 1.26 g/cm³ and the surface tension at 20°C and a concentration of 1 g/L in water is 74.2 mN/m. The self-ignition temperature is 396°C and it was found that after removal of the ignition source, the flame extinguished after 21 seconds and no propagation of combustion was observed within 4 minutes, so the substance is considered to be non-flammable. The dissociation constant has been read across from the respective acid, with measured pK_A1 of 4.41 and pK_A2 of 5.28, indicating that the substance is expected to be in the acid (anionic) form at environmental pH. The water solubility of dilithium adipate is 343 g/L at 20°C, based on lithium analysis, and 406 g/L, based on adipate analysis. The log Pow for dilithium adipate is <-0.9 for adipate and <-3.5 for lithium.

Dilithium azelate (C9) is a solid at ambient temperature, with a vapour pressure of <1.3 x 10^-8 Pa at 20°C and <2.9 x 10^-8 Pa at 25°C. Dilithium azelate has a melting point and boiling point of >400°C, and a density of 1.32 g/cm³. The surface tension at 20°C and a concentration of 1 g/L in water is 73.2 mN/m. The self-ignition temperature is 294°C and it was found that after removal of the ignition source, the flame extinguished after 8 seconds and no propagation of combustion was observed within 4 minutes, so the substance is considered to be non-flammable. The dissociation constant has been read across from the respective acid, with measured pK_A1 of 4.53 and pK_A2 of 5.33, indicating that the substance is expected to be in the acid (anionic) form at environmental pH. The water solubility of dilithium azelate is 192 g/L at 20°C, based on lithium analysis, but the results based on azelate analysis were not conclusive. The log Pow for dilithium azelate is -3.3 for azelate and <-4.0 for lithium.

Dilithium sebacate (C10) is a solid at ambient temperature, with a vapour pressure of <1.3 x 10^-8 Pa at 20°C and <2.9 x 10^-8 Pa at 25°C. Dilithium sebacate has a melting point and boiling point of >400°C, and a density of 1.29 g/cm³. The surface tension at 20°C and a concentration of 1 g/L in water is 73.1 mN/m. The self-ignition temperature is 329°C and it was found that after removal of the ignition source, the flame extinguished after 10 seconds and no propagation of combustion was observed within 4 minutes, so the substance is considered to be non-flammable. The dissociation constant has been read across from the respective acid, with measured pK_A1 of 4.59 and pK_A2 of 5.59, indicating that the substance is expected to be in the acid (anionic) form at environmental pH. The water solubility of dilithium sebacate is 76.6 g/L at 20°C, based on lithium analysis, and 68.5 g/L based on sebacate analysis. The log Pow for dilithium sebacate is -2.1 for sebacate and <-3.1 for lithium.

The similarity in properties between the tested samples of dilithium adipate, dilithium azelate and dilithium sebacate supports the grouping of the substances into a single category of lithium salts of dicarboxylic acids C6-C10 and read across between the substances for environmental fate, ecotoxicity and mammalian toxicity endpoints. Any further substances which have not been registered but would fall within the category definition are expected to follow the identified trends in properties.