Reaction mass of Amines, coco alkyl and β-Alanine, N-(2-carboxyethyl)-, N-coco alkyl derivs. and β-Alanine, N-coco alkyl derivs.

Adsorption / desorption

Description of key information

The test substance is considered to have low potential for adsorption and no further testing is required. A conservative value of 1000 is considered for Koc.

Key value for chemical safety assessment

Koc at 20 °C:

1 000

Additional information

Waiver. In accordance with column 2 of REACH Annexes XIII, the adsorption / desorption study (required in section 9.3.1 and 9.3.3) do not need to be conducted if, based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g. the substance has a low octanol-water partition coefficient). The log partition coefficient of the test substance was predicted to be <3.0. Therefore, the test substance is considered to have low potential for adsorption and no further testing is required.

915-790-0 consists of ‘Reaction mass of Amines, coco alkyl and ß-Alanine, N-(2-carboxyethyl)-, N-coco alkyl derivs. and ß-Alanine, N-coco alkyl derivs’ (official name). The composition comprises
•    Coco alkyl amines (CAS 61788-46-3; 15-30%)
•    ß-Alanine, N-coco alkyl derivatives (CAS 84812-94-2; approximately half of remainder)
•    ß-Alanine, N-(2-carboxyethyl)-, N-coco alkyl derivatives (CAS 99035-54-8; approximately half of remainder)
Alkyl chain length distribution conforms with coco fatty acid distribution, with primarily C₁₂and C₁₄chains.
It is assumed that the components do not interact (not very likely) and an overall Koc can be estimated as a weighted sum of individual values (as for the Kow average).
PCKOC (EPISuite) estimates are calculated for the most important individual components (and some model compounds); note that PCKOC does not provide experimental values:

	KOCWIN			pKa (SPARC)
	MCI	KOW	Remark
octylamine	2.688	2.507		10.41
decylamine	3.21	2.994		10.41
dodecylamine	3.731	3.536		10.41
tetradecylamine	4.252	4.084		10.41
hexadecylamine	4.773	4.626		10.41
ß-Alanine, N-coco alkyl derivatives (C12)	3.12	1.091	pH	3.58, 10.87
ß-Alanine, N-coco alkyl derivatives (C14)	3.643	1.639	pH	3.58, 10.87
ß-Alanine, N-(2-carboxyethyl)-, N-coco alkyl derivatives (C12)	4.101	0.767	pH	3.16, 3.81, 7.59
ß-Alanine, N-(2-carboxyethyl)-, N-coco alkyl derivatives (C14)	4.62	1.269	pH	3.16, 3.81, 7.59
				3.16, 3.81
hexadecanoic acid	3.547	4.122	pH	3.16, 3.81

PCKOC offers two prediction models, one based on molecular connectivity indices, and one based on log Kow - one of the advantages of the Kow model is that it can accommodate user-input for ‘better’ (measured) Kow values. In the absence of any experimental data, for simple substances, the MCI and KOW models should present comparable results, since they are based on the same training set. Both models do in fact, implicitly or explicitly, embrace the notion that KOC can be regarded as a partition coefficient where the relevant compartments are water and an organic material fraction associated with soil or sediment; while this is a useful approximation for nonpolar and neutral polar substances, it regularly breaks down for strongly polar and/or charges substances.
 
This shows the values for amines, including the trend in the homologous series, are indeed quite similar between the two models. Since these substances are not very polar, the estimated Kow values can be regarded as relevant.
For the ß-alanine derivatives and the N-(2-carboxyethyl) ß-alanine derivatives, this is no longer true, with the Kow-based model predicting a much lower (log) Koc than the MCI model. The difference is in the Kow predictions (see the EPISuite output), where it looks like the KOWWIN model explicitly takes into account the amino acid structure. Kow-based estimates are generally regarded as more reliable than the MCI based estimates. For that reason, the entire approach was based on PCKOC’s Kow-based estimates. For the amino acids, PCKOC warns that the Koc may be subject to variability depending on pH. In fact, PCKOC estimates are for the undissociated acids. The (relevant) pKa values (estimated values using SPARC) suggest that the ß-alanine-derivatives will be dissociated appreciably at environmentally relevant pH. In a dissociated state, association with organic matter will be lower, but adsorption to inorganic matter in sediment and soil may be significantly higher. There is no simple way of accounting for these processes.

Assuming, for the sake of example, a product with a composition of 20% coco alkylamines, 40% ß-Alanine, N-coco alkyl derivatives and 40% ß-Alanine, N-(2-carboxyethyl)-, N-coco alkyl derivatives, each with a chain length distribution of 60% C12, and 40% C14, a weighted average log Koc (based on Kow-based estimates) value would be 1.662. Other potential product compositions would not differ too much from this value - a composition with 35% coco alkylamines with 10% C10 would result in a log Koc value of 1.97.  Therefore, overall, it is conservative to say that log Koc will very likely be < 3.0.

 

[LogKoc: 3.0]