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Adsorption / desorption

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Description of key information

Parent compound isobutyryl chloride and hydrolysis product isobutyric acid: Adsorption to solid soil phase is not expected.
However, the assessment of the parent compound may be of low relevance, due to the rapid hydrolysis of the acid chlorid in aqueous solutions.

Key value for chemical safety assessment

Additional information

Parent compound isobutyryl chloride:

The adsorption potential of isobutyryl chloride (CAS 79 -30 -1) was calculated using EPI Suite v.4.10. The estimation for the uncharged molecules using the MCI and the Kow method of the KOCWIN v2.00 module from SRC EPISuite v4.10 are listed below.

Uncharged molecule:

- MCI method: Koc = 2.359; log Koc = 0.3728

- Kow method: Koc = 8.694; log Koc = 0.9392

Based on the MCI method of the uncharged molecule, adsorption to solid soil phase is not expected.

Isobutyryl chloride (CAS 79 -30 -1) rapidly decomposes in water and forms HCl (CAS 7647 -01 -0) and isobutyric acid (CAS 79 -31 -2).
Therefore, the model calculation may be of low relevance.

Hydolysis compound isobutyric acid:

The adsorption potential was estimated for isobutyric acid (CAS 79 -31 -2) using the MCI and the Kow methods of the KOCWIN v2.00 module from SRC EPI Suite v4.10. These estimates are representative for uncharged molecules. The substance ionises in aqueous solutions, therefore the adsorption coefficient was calculated according to Franco & Trapp (2008) as well as according to the REACH Guidance (2008) to correct for the charged molecule at pH 4, 5, 7 and 9. The Koc values are listed below.

 

Uncharged molecule:

- MCI method: Koc = 2.252; log Koc = 0.3526

- Kow method: Koc = 4.739; log Koc = 0.6757

Charged molecule:

- Franco & Trapp, 2008:

pH 4: Koc = 45; log Koc = 1.65

pH 5: Koc = 45; log Koc = 1.65

pH 7: Koc = 45; log Koc = 1.65

pH 9: Koc = 45; log Koc = 1.65

Based on the corrections for the charged molecule according to Franco & Trapp (2008), adsorption to the solid soil phase is not expected.