N,N,N',N'-tetramethylhexamethylenediamine

Biodegradation in water: screening tests

Description of key information

The substance is not readily biodegradable (according to OECD criteria) but inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Additional information

Parent compound:

In an enhanced OECD 301B ready biodegradability study, using non-adapted activated sludge from a municipal sewage treatment plant as inoculum, the substance was found to be degraded by 87% after 60 days based on CO2 evolved (BASF SE 2012, report no. 22G0487/11G091). However, the substance was only 56% degraded by day 32 and the 10-day window was not met. Hence, the substance cannot be considered readily biodegradable, but these results strongly indicate that the substance is inherently biodegradable.

The data of an inherent biodegradability test conducted equivalently to an OECD 302 B study support this indication; the substance was 97% degraded after 13 days based on DOC (BASF SE 1986, report no. 01.449/86). As inoculum, industrial activated sludge was used.

The model CATALOGIC 301C v11.15 (OASIS Catalogic v5.13.1.156) was used to predict potential metabolites of N,N,N',N'-tetramethylhexane-1,6-diamine (BASF SE, 2020). The substance was within the applicability domain of the model (100%)

Predicted metabolites:

Metabolites (n = 29) from the degradation of N,N,N',N'-tetramethylhexane-1,6-diamine (CAS 111-18-2) were predicted using the QSAR model Catalogic 301C v11.15. The metabolites are identified by their SMILES code. The table below also lists the estimated quantity of appearance from the degradation as well as the log Kow and the biodegradability (BOD prediction). The metabolites with a quantity of > 0.001 mol/mol parent are regarded to be relevant for the environmental assessment. It was attempted to identify the relevant metabolites either via the QSAR Toolbox and/or the advanced search option for substances on the ECHA website. In case a name and/or CAS number was assigned, the PBT/vPvB status according to the ECHA website was checked.

Based on the available information, it can be concluded that all metabolites have a log Kow < 3. Sixteen of the 29 metabolites have a predicted quantity of > 0.001 mol/mol parent and are regarded as relevant for further assessment. The majority of these metabolites (11/16) are not readily biodegradable (< 60% after 28 days, based on BOD), but all of these 16 metabolites have a log Kow < 3; therefore, a significant bioaccumulation potential is not expected. It can be concluded that these substances are not PBT/vPvB substances.

Their toxicity (T) was not further assessed as no critical combination of potential P/vP (= not readily biodegradable) and potential B/vB (log Kow > 3) properties was observed.

 

Table: QSAR prediction for CAS-#111-18-2 using CATALOGIC 301C v11.15 – July 2018 (OASIS CATALOGIC v5.13.1.156; metabolites with a quantity > 0.001 mol/mol parent after 28 d are highlighted by grey background and bold type; metabolite no: according to (Q)SAR model Catalogic v11.15 – July 2018 (OASIS CATALOGIC v5.13.1.156))

#	Metabolite (no)	SMILES	Substance name (CAS)	Quantity (mol/mol parent)	Log Kow	BOD prediction (% after 28 d)	PBT-Assessment: ECHA (disseminated substances)
parent	1	CN(C)CCCCCCN(C)C	N,N,N',N'-tetramethylhexane-1,6-diamine (CAS 111-18-2)	0.683	1.70	8	not PBT/vPvB
1	15	C=O	Formaldehyde (CAS 50-00-0)	0.0063	0.35	100	not PBT/vPvB
2	2	CNCCCCCCN(C)C	1,6-Hexanediamine, N,N,N'-trimethyl- (CAS 1862-11-9)	0.0266	1.49	36	not registered under REACH
3	22	CN(C)CCCCCCN(C)CO	not identified	0.1016	0.24	8	not identified
4	16	OC=O	Formic acid (CAS 64-18-6)	3.87E-06	-0.46	100	not checked
5	14	CN	Methanamine (CAS 74-89-5)	0.0349	-0.64	64	not PBT/vPvB
6	3	CN(C)CCCCCC=O	Hexanal, 6-(dimethylamino)- (CAS 2554-94-1)	0.0035	1.00	37	not registered under REACH
7	21	CN(C)CCCCCCN	1,6-Hexanediamine, N,N'-dimethyl- (CAS 13093-04-4)	0.0326	1.02	29	not registered under REACH
8	23	CN(C)CCCCCCNCO	not identified	0.0019	0.02	36	not identified
9	25	CNCCCCCCN(C)CO	not identified	0.0019	0.02	37	not identified
10	4	CN(C)CCCCCC(O)=O	Hexanoic acid, 6-(dimethylamino)- (CAS 1072-09-9)	1.38E-06	-1.94	34	not checked
11	24	NCO	Cyanooxy (CAS 22400-26-6)	5.668E-08	-2.10	100	not checked
12	26	CN(CCCCCC=O)CO	not identified	0.0035	-0.46	39	not identified
13	33	CN(CCCCCCN)CO	not identified	0.0021	-0.44	30	not identified
14	5	CN(C)CCCC=CC(O)=O	not identified	1.38E-06	-0.66	34	not checked
15	27	CN(CCCCCC(O)=O)CO	not identified	5.667E-08	-3.41	36	not checked
16	6	CN(C)CCCC(O)CC(O)=O	not identified	1.38E-06	-3.48	31	not checked
17	28	CN(CCCC=CC(O)=O)CO	not identified	5.667E-08	-2.12	36	not checked
18	7	CN(C)CCCC(=O)CC(O)=O	not identified	1.38E-06	-3.99	31	not checked
19	29	CN(CCCC(O)CC(O)=O)CO	not identified	5.667E-08	-4.54	33	not checked
20	8	CN(C)CCCC(O)=O	Butanoic acid, 4-(dimethylamino)- (CAS 693-11-8)	0.1226	-2.92	8	not registered under REACH
21	20	CC(O)=O	Acetic acid (CAS 64-19-7)	1.43E-06	0.09	100	not checked
22	30	CN(CCCC(=O)CC(O)=O)CO	not identified	5.667E-08	-5.46	33	not checked
23	9	CNCCCC(O)=O	Butanoic acid, 4-(methylamino)- (CAS 1119-48-8)	0.0026	-3.14	66	not registered under REACH
24	31	CN(CCCC(O)=O)CO	not identified	0.0051	-4.39	9	not identified
25	10	OC(=O)CCC=O	Butanoic acid, 4-oxo- (CAS 692-29-5)	0.0015	-0.42	91	not registered under REACH
26	19	NCCCC(O)=O	2-Butynoic acid, 4-amino- (CAS 56-12-2)	0.0023	-3.60	57	not PBT/vPvB
27	32	OCNCCCC(O)=O	not identified	6.18E-04	-4.60	68	not checked
28	11	OC(=O)CCC(O)=O	Butanedioic acid (CAS 110-15-6)	8.80E-04	-0.75	90	not checked
29	12	CCC(O)=O	Propanoic acid (CAS 79-09-4)	0.0077	0.58	100	not PBT/vPvB

Conclusion:

The substance is considered to be inherently biodegradable, but not readily biodegradable (according to OECD criteria).