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Reaction mass of dipotassium 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinate and dipotassium 2-(4,5-dimethy-1H-pyrazol-1-yl) succinate is an organic solid with a low vapour pressure of 6.8E-3 Pa at 20 °C (vapour pressure balance, OECD 109). The substance is soluble in water (79.5 g/L; OECD 105) and has a low log Pow of -2.5 at 20 °C (OECD 105). The substance is not stable at environmental conditions. On contact with water the substance dissociates forming K+ and the conjugate acid (Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid; CAS 2241455-89-8). A dissociation constant (pKa) of 4 was determined for the substance. Thus, a dissociation of the substance and formation of the conjugate acid at environmental relevant pH of 5 - 9 can be expected. The substance Reaction mass of dipotassium 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinate and dipotassium 2-(4,5-dimethy-1H-pyrazol-1-yl) succinate will most probably not exist in the environment and thus persistency of the target substance can be excluded. The degradation of the conjugate acid was investigated in a study following OECD 301A. The recorded degradation rate was 0% and thus the substance is not readily biodegradable according to the OECD criteria. An available study on the degradation of the conjugate acid in soil determined a rapid degradation to 3,4-dimethylpyrazole (DMP) with normalized half-lives of 1.5 - 3.3 d (OECD 307). Degradation of DMP was tested in parallel and normalized half-lives of 3.8 - 8.9 d of the substance in soil were determined. Thus, the conjugate acid of the target substance and its metabolite degrade rapidly in the soil compartment. The substance is expected to have low adsorption potential based on the low log Pow (log Pow -2.5). The assumption is supported by experimental data available for the conjugate acid indicating a lowadsorption potential (log Koc of 0.6 - 2.1; OECD 106). The determined Koc values indicate a moderate mobility in soil. Furthermore, an accumulation in air and the subsequent transport to other environmental compartments is not likely due to the low vapour pressure of the target substance and the conjugate acid (VP:6.8E-3 Pa at 20 °C and 0.002 Pa at 25 °C, respectively). Bioaccumulation of Reaction mass of dipotassium 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinate and dipotassium 2-(4,5-dimethy-1H-pyrazol-1-yl) succinate and the conjugate acid is unlikely based on the log log Pow of both substances.