Fatty acids, C16-18 and C18-unsatd., branched and linear

Endpoint summary

Additional information

A summary of physico-chemical properties of the dimerised fatty acids and their derivatives is provided in the tables below. Table 1 contains relevant endpoints from Sec. 4.1 (Appearance) to 4.7 (Partition coefficient) and Table 2 from Sec. 4.8 (Water solubility) to 4.22 (Viscosity). As UVCB substances are derived from natural sources with highly variable compositions, some measures of physico-chemical properties are inapplicable or not accurate enough for a trend analysis. A detailed justification for the grouping of chemicals and read-across is provided in the technical dossier (see IUCLID Section 13).

Table 1. Summary of physico-chemical endpoints for dimerised fatty acids (I) 

Chemical Name	CAS No.	Appearance	Melting / freezing point	Boiling point	Density	Vapour pressure	Partition coefficient (log Pow)
Fatty acids, C16-18 and C18-unsaturated, branched and linear (monomer)	68955-98-6	Viscous liquid to solid	23 °C to 32 ° C (pour point)	decomposition	Experimental result: 0.90-0.91 g/mL at 19°C	Weight of Evidence: <1 Pa at 25 °C	Experimental result: Log Kow 4.9 at 25 °C   Judged to be >4
Octadecanoic acid, branched and linear (hydrogenated monomer)	68201-37-6	Paste solid	49 °C (pour point)	decomposition	Experimental result: 0.9 g/mL at 19 °C	Weight of Evidence: <1 Pa at 25 °C	Experimental result: Log Kow 5.6 — 6.1   Judged to be >4
Isooctadecanoic acid	30399-84-9	liquid	-21 °C	decomposition	Experimental result: 0.9 g/mL at 19 °C	(Q)SAR: 0.000445 Pa at 25°C	(Q)SAR: Log Kow 7.87 The estimation refers to the isooctdecanoic acid in unique form. Judged to be >4
Fatty acids, C16 -18 and C18-unsaturated, dimerized	71808-39-4	liquid	11 °C	decomposition	Experimental result: 0.92 to 0.94 g/mL at 19 °C	Weight of Evidence: <1 Pa at 25 °C	Experimental result Log Kow 2.4 — 7.5   Judged to be >4
Fatty acids, C18-unsaturated, dimers	61788-89-4	liquid	-18 °C to -12 °C	decomposition	Experimental result: 0.95-0.96 g/mL at 19°C	Weight of Evidence: <1 Pa at 25 °C	Experimental result: Log Kow 1 — 2.5   Judged to be >4
Fatty acids, C18-unsaturated, dimers, hydrogenated	68783-41-5	liquid	- 15 °C	decomposition	Experimental result: 0.95 g/mL at 19 °C	Weight of Evidence: <1 Pa at 25 °C	Experimental result. Log Kow 0.7 — 6.2   Judged to be >4
Fatty acids, C18-unsaturated, trimers	68937-90-6	Liquid	-3 °C	decomposition	Experimental result: 0.97 g/mL at 19 °C	Weight of Evidence: <1 Pa at 25 °C	Experimental result: Log Kow : 2.2->6 (8.9) Judged to be >4

Table 2. Summary of physico-chemical endpoints for dimerised fatty acids (II) 

Chemical Name	CAS No.	Water solubility	Surface tension	Flash point	Dissociation constant	Viscosity
Fatty acids, C16-18 and C18-unsaturated, branched and linear	68955-98-6	Experimental result: 0.6 mg/L	Experimental result: 32.5 mN/m at 30 °C	Experimental result: 204 °C at 101.3 kPa	(Q)SAR: pKa 4.72 — 4.75 at 25 °C	Experimental result: 21 to 27 mPa s at 40 °C
Octadecanoic acid, branched and linear	68201-37-6	Experimental result: 2.5 mg/L	Experimental result: 30 mN/m at 30 °C	Experimental result: 208 °C at 101.3 kPa	(Q)SAR: pKa 4.72 — 4.75 at 25 °C	Experimental result: 24 mPas at 50 °C
Isooctadecanoic acid	30399-84-9	Experimental result: 0.24 mg/L	Experimental result: 32 mN/m at 23.7 °C	Experimental result: 208 °C at 101.3 kPa	(Q)SAR: pKa 4.75 at 25 °C	Experimental result: 39 mPas at 40 °C
Fatty acids, C16-18 and C18-unsaturated, dimerized (crude dimer)	71808-39-4	Experimental result: <0.41 mg/L (water solubility below detection limit)	Experimental result: 30 mN/m at 30 °C	Experimental result: 226 °C at 101.3 kPa	Not required	Experimental result: 21 to 27 mPas at 40 °C
Fatty acids, C18-unsaturated, dimers	61788-89-4	Experimental result: <0.12 mg/L (water solubility below detection limit)	Experimental result: 33.3 mN/m at 24 °C	Experimental result: 304 °C at 101.3 kPa	Not required	Experimental result: 2255 to 1827mPas at 40°C
Fatty acids, C18-unsaturated, dimers, hydrogenated	68783-41-5	Experimental result: < 0.52 mg/L (water solubility below detection limit)	Experimental result: 32.3 mN/m at 24 °C	Experimental result: 300 °C at 101.3 kPa	Not required	Experimental result: 2671 mPas at 40 °C
Fatty acids, C18 -unsaturated, trimers	68937-90-6	Experimental result: < 0.37 mg/L (water solubility below detection limit)	Experimental result: 45 mN/m at 24.5 °C	Experimental result: 350 °C at 101.3 kPa	Not required	Experimental result: 7664 mPas at 40 °C

It can be concluded that the physico-chemical properties are similar or follow a regular pattern over the category. The patterns observed depend on whether the substance is predominantly monomer (CAS Nos. 68955-98-6, 68201-37-6, 30399-84-9), or it is predominantly oligomer (dimers: CAS Nos. 71808-39-4, 61788-89-4, 68783-41-5, or trimer: CAS No. 68937-90-6).

Endpoints demonstrating similarity: boiling point (decomposition), density (0.9-1.0 g/cm³), vapour pressure (low volatility), partition coefficient (log Kow > 4), surface tension (30-45 mN/m at room temperature), flash point (high: 200-350 °C).

Endpoints following regular trends/patterns: water solubility (for predominantly monomers: 0.2 - 15 mg/L, for predominantly oligomers below any detection limit under 1 mg/L), dissociation constant (calculated only for predominantly monomers, not required for predominantly oligomers), viscosity (low for monomers, considerably higher for dimers and the highest for trimer; exception: the value for crude dimer, CAS No. 71808-39-4, is in the range characteristic for predominantly monomers).