1-Propanaminium, 2-hydroxy-N-(2-hydroxypropyl)-N,N-dimethyl-, esters with C18-unsatd. fatty acids, Me sulfates (salts)

Endpoint summary

Additional information

MDIPA Esterquat C18 unsatd. is described as yellow turbid liquid at 20°C and 1013 hPa (visual assessment during test on physicochemical properties (melting point)).

The melting point of MDIPA Esterquat C18 unsatd. was determined according to OECD Guideline 102 (27 July 1995) and EU Method A.1 (30 May 2008) using differential scanning calorimetry. The sample was slowly cooled down to -100°C to enhance the possibility of crystallisation. Upon heating of the sample small enthalpic effects were registered between -55 and -10°C, caused by phase and glass transitions. The effects, however, were too small to be caused by melting: the test substance had solidified amorphously and no melting point could be found.

The boiling point of MDIPA Esterquat C18 unsatd. was determined according to OECD Guideline 103 (27 July 1995) and EU Method A.2 (30 May 2008) using differential scanning calorimetry. A major endothermic peak was registered with a peak maximum temperature at 287°C and an extrapolated onset temperature of 244°C, followed by two smaller endothermic peaks (378-380°C and 447-450°C). The mass loss after the measurement was 97.8%. No boiling point for MDIPA Esterquat C18 unsatd. was detected prior to decomposition at ca. 200°C.

The density of MDIPA Esterquat C18 unsatd. was determined according to OECD Guideline 109 (27 July 1995) and EU method A.9 (30 May 2008) using the pycnometer method. The density of MDIPA Esterquat C18 unsatd. is reported to be 0.987 g/cm³ at 20°C.

In accordance with column 2 of REACH regulation annex VII, a granulometry test does not need to be conducted as the substance is a liquid.

The vapour pressure of MDIPA Esterquat C18 unsatd. was determined according to OECD Guideline 104 (23 March 2006) and EU Method A.4 (30 May 2008) using the vapour pressure balance method. Based on the experimental results, the vapour pressure of the test item at 20°C was calculated to be 5E-06 hPa using the Antoine equation.

According to REACH regulation (Annex XI, 2.), the study does not need to be done if it is technically not feasible: The determination of the n-octanol/water partition coefficient log Kow is technically not feasible due to the surface-active properties of the test substance.

However, measured data from a structurally related substance are provided: the log Kow of DODMAC is reported to be 3.8.

The n-octanol/water partition coefficients (log Kow) of the main constituents of MDIPA Esterquat C18 unsatd. were calculated to be in the range of 13.8 - 14.7 (Episuite v4.11, KOWWIN v1.68). However, charged molecules are outside of the applicability domain. Thus, the calculation is not reliable.

Calculated or measured Kow values are of limited practical use for cationic substances to estimate their physical properties or behaviour in the environment. An inherent property of cationic surfactants is that they accumulate at the interface between two phases. Thus, the accurate measurement of the Kow for any surfactant is difficult. Even if such measurements were made accurately, the Kow is not an appropriate hydrophobicity parameter for reliably predicting environmental behaviour because cationic substances in the environment instantaneously form complexes with naturally occurring negatively charged constituents in sewage, soils, sediments and with dissolved humic substances in surface waters.

The water solubility of MDIPA Esterquat C18 unsatd. was determined according to ASTM International E 1148 – 02, using turbidity measurement.The water solubility was 1.22 mg/L at 20°C.

The surface tension of MDIPA Esterquat C18 unsatd. was determined according to OECD Guideline 115 (27 July 1995) and EU Method A.5 (30 May 2008) using the ring tensiometer method. A surface tension of 37.5 mN/m at 20°C was determined at a test item concentration of 1.117 g/L. Based on the results, MDIPA Esterquat C18 unsatd. is considered to be surface-active.The measurement was performed at a concentration exceeding water solubility.

According to REACH Regulation (Annex XI, 1.), the study on flammability needs not to be done if the available data are sufficient for assessment. For liquids the relevant endpoint is the flash point.

The flash point of MDIPA Esterquat C18 unsatd. was determined according to EU Method A.9 (30 May 2008) and ISO 2719:2002 using the Pensky-Martens closed cup method. The flash point was determined to be 147°C at 1013 mBar.

The auto-ignition temperature of MDIPA Esterquat C18 unsatd. was determined according to EU Method A.15 (30 May 2008) and DIN 51794 (2003). The auto-ignition temperature was determined to be 340°C at 1012 hPa.

In accordance with column 2 of REACH regulation annex VII, explosive properties testing does not need to be conducted as there are no chemical groups associated with explosive properties in the molecule.

In accordance with column 2 of REACH regulation annex VII, 7.13, oxidising properties testing does not need to be conducted, as the substance does not contain any structural groups known to be correlated with a tendency to react exothermally with combustible material.

According to REACH regulation, Annex IX, column 1, a study on stability on organic solvents has to be conducted only if the stability in organic solvent is considered to be critical.

According to REACH regulation (Annex XI, 1.), a determination of the dissociation constant does not need to be conducted if the available data are sufficient for assessment. MDIPA Esterquat C18 unsatd. is a salt which will dissociate completely in aqueous solution. Moreover, there are no functional groups capable of acid-base-reactions at environmentally relevant pH.

The dynamic viscosity of MDIPA Esterquat C18 unsatd was determined according to OECD Guideline 114 (12 May 1981) and DIN 53015 using a rolling ball viscosimeter. The test substance did not behave like a Newtonian fluid: the measured viscosity depended on the history of the test item. As the measured viscosity data tend to approach asymptotically an equilibrium value, a lower limit for the viscosity of the test substance was deduced. The dynamic viscosity of MDIPA Esterquat C18 unsatd. is > 17000 mPa s at 20°C.

 

JUSTIFICATION FOR READ-ACROSS 

Substance identities

The target substance MDIPA-Esterquat C18 unsatd. is a UVCB substance composed of diesters of unsaturated C18 fatty acids with MDIPA (Methyldiisopropanol amine) as amine backbone.

 

The source substance DODMAC (Dimethyldioctadecylammonium chloride) exhibits large structural similarities with the target substance. Details are described below.

 

	Target substance	Source substance
	MDEA-Esterquat C18 unsatd.	DODMAC
CAS number	95009-13-5	61789-80-8
EC number	305-741-6	263-090-2
Fatty Acid	C18‘, C18‘‘, C18‘‘‘ (IV = 110)	C16-18, C18‘
Chain length distribution	<C16 no relevant amount expected C16 </=7% C18 </= 4% C18‘ 55-65% C18‘‘ 18-25% C18‘‘‘ 6-12% >C18 </= 5%	C12: </=2 % C14: 1 - 5 %  C16: 25 - 35 %  C18: ca. 65 %  C 20: </=2 %
Amine	MDIPA	---
Anion	Methyl sulphate	Chloride

 

Structural similarity

a. Structural similarity and functional groups

Figure 1 (see attachment): Structures of source substance (DODMAC) and target substance (MDIPA Esterquat C18 unsatd.)

The target substance, MDIPA-Esterquat C18 unsatd., consists of an amine backbone (MDIPA = Methyldiisopropanol amine) esterified with unsaturated long-chained fatty acids, C18´, C18´´, C18´´´(IV = 110). The main constituent is the dialkylester compound, next to that small amounts of the monoalkylester may be formed. The amine function is quaternised with two methyl groups. The counterion is Methosulfate.

The source substance DODMAC (Dimethyldioctadecylammonium chloride) is one of the active components of the technical product DHTDMAC (dihydrogenated tallow alkyl dimethyl ammonium chloride). DHTDMAC is produced of tallow fatty acid via the nitrile to result in the amine, which is then methylated twice to the quaternised amine. The counter ion is Chloride. DODMAC has a similar chain length distribution as the target substance and contains a quaternised and dimethylated amine function.

Differences

The chemical structure of the target substance MDIPA-Esterquat C18 unsatd. contains, in contrast to the source substance, two polar ester moieties which are susceptible to hydrolysis and /or degradation.

 

Comparison of physicochemical properties

	Target substance	Source substance
Endpoints	MDIPA-Esterquat C18 unsatd.	DODMAC
Molecular weight	ca. 796 g/mol	586.52 g/mol
Physical state at 20°C / 1013 hPa	liquid	Solid
Melting point	Amorphous solidification between -55 and -10°C	72-122 °C
Boiling point	Decomposition at ca. 200°C	decomposition at 135°C
Surface tension	37.5 mN/m at 20°C	11 mN/m at 20 °C
Water solubility	1.22 mg/L at 20°C	2.7 mg/L
Log Kow	No data, read-across from DODMAC	3.8
Vapour pressure	5E-08 Pa at 20°C	negligible because of the salt character

 

Experimental data on log Kow are not available for the target substance MDIPA-Esterquat C18 unsatd. A read-across approach from the structurally similar substance DODMAC was applied. Both substances have a very low vapour pressure.

There are, however, differences in melting point, surface tension. The differences in melting point result from the higher degree of unsaturation of the target substance MDIPA-Esterquat C18 unsatd. in comparison to the source substance DODMAC.

 

Conclusion

The structural similarities between the source and the target substance support the read-across hypothesis. Therefore, it can be concluded that the log Kow of the target substance MDIPA-Esterquat C18 unsatd. will be in a comparable range as the log Kow of the source substance DODMAC.

However, the log Kow is not an appropriate hydrophobicity parameter for reliably predicting environmental behavior of surfactants because cationic substances in the environment instantaneously form complexes with naturally occurring negatively charged constituents in sewage, soils, sediments and with dissolved humic substances in surface waters.

The predictive power of the log Kow for the partitioning to soil, sediment and sludge or its bioaccumulation potential is considered to be limited, because the common Koc derivations are not valid for surface active substances like MDIPA-Esterquat C18 unsatd. Therefore the log Kow values cannot be used to derive the environmental distribution constants. Instead as a more reliable basis, the data on sorption and bioaccumulation will be used.

 

References

EU, 2009: European Union Summary Risk Assessment Report - dimethyldioctadecylammonium chloride (DODMAC) - with addendum, available online: http: //publications. jrc. ec. europa. eu/repository/handle/111111111/5276

 

HERA, 2008: Esterquats Environmental Risk Assessment Report, available online: http: //www. heraproject. com/files/17-E-01-03-2008%20%20HERA%20EQ%20Environment%20Final%20Draft. pdf