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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption of the test item (represented by C13H29N, C23H49N, C26H55N and C29H61N) to the solid soil phase is expected.

Key value for chemical safety assessment

Additional information

Di-tridecylamine, branched and linear (CAS 101012-97-9) is a mixture of (predominantly) di-alkyl amines with varying alkyl-chain length in a range between C13 and C29. The main fraction (81.2%) consists of di-tridecylamine (C26H55N; CAS 57157-80-9).

Regarding the main fraction of the mixture (C26H55N, represented by CAS 57157 -80 -9) and using the Molecular Connectivity Index (MCI), the log Koc for the uncharged molecule was estimated to be 7.02 (Koc = 1040000). Based on the calculated log Pow of 11.47 (Kowwin), the log Koc was estimated at 7.23 (Koc = 1682000) (both estimations by KOCWIN v2.00 for the uncharged molecule; BASF SE, 2011).

However, the calculated pKa of 10.80 (SPARC, 2011) indicates that di-iso-tridecylamine (CAS 57157 -80 -9) will exist primarily as a cation in the environment (pH 5 to 9) and cations generally adsorb stronger to soils containing organic carbon and clay than their neutral counterparts. Regarding the charged molecule, at pH 7 the log Koc was estimated to be 4.7 (Koc = 49787) following the method of Franco & Trapp (2008, 2009, 2010) and using the pKa of 10.80 (BASF SE, 2013). The correction was performed for pH 5, 7, and 8, which represents 98% of the European soils. The value at pH 7 will be used as key value, i.e. for PEC and PNEC calculations.

Regarding the other compounds of the test item (CAS 101 012 -97 -9), the pH-corrected log Koc for molecules with a C-chain length between C23 and C29 is expected to be at a similar level (log Koc = 4.7; pH 7). For the mono alkyl amine (C13H29N, CAS 35723 -81-0) the corrected log Koc is estimated a little lower at 4.58 (BASF, 2013).

SMILES code

Mol. formula

CAS No.

Input parameter

Corrected Koc

(log Koc)

log Kow*

pKa**

pH 5

pH 7

pH 8

NCCCCCCCCCCC(C)C

C13H29N1

35723-81-0

5.18

10.41

37923

(4.58)

37923

(4.58)

37805

(4.58)

C(C)(C)CCCCCCCCNCCCCCCCCCC(C)C

C23H49N1

-

9.99

10.80

49656

(4.70)

49688

(4.70)

49971

(4.70)

CC(C)CCCCCCCCCCNCCCCCCCCCCC(C)C

C26H55N1

57157-80-9

11.47

10.80

49657

(4.70)

49787

(4.70)

50968

(4.71)

CC(C)CCCCCCCCCCCCCCNCCCCCCCCCC(C)C

C29H61N1

-

12.94

10.80

49661

(4.70)

50135

(4.70)

54443

(4.74)

* KOWWIN v1.68 estimation for the uncharged molecule

** pKa from SPARC estimation (see chapter 4.21)

The data refer to the charged molecules at pH 5, 7, and 8.

These values are supported by the analogue substance octadecylamine (CAS 124 -30 -1), where a log Koc of 4.54 (Koc = 34850) was determined experimentally (Slangen, 2000). Octadecylamine is a primary alkylamine which is used as read-across substance for tridecylamine, branched and linear (CAS 86089 -17 -0). It has the molecular formula C13H29N1 and is also part of the test item discussed here.

Primary alkylamines are surface active substances which at environmentally relevant pH occur predominantly as charged species. As already stated in the EU RAR on primary alkylamines (EC, 2004; draft) as well as in the ECHA Guidance Document R.7A (ECHA, 2008), it is assumed that ionic interactions play a more important role than hydrophobic partitioning with organic matter. An interaction with negativ charges of humic substances or with mineral particles is very likely. Therefore, the influence of the chain length on the sorption behaviour is expected to be low.