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Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

MDEA Esterquat C18 satd. is an organic substance which is characterized as yellowish waxy substance at 20°C and 1013 hPa.

Physical and chemical data of MDEA Esterquat C18 satd. are not available. Therefore studies of the structurally similar source substances MDEA-Esterquat C16-18 and C18 unsatd. and DODMAC (Dimethyldioctadecylammonium chloride) are taken into consideration. A justification for read across is given below.

The melting point was determined to be 54°C at atmospheric pressure (OECD Guideline 102 and EU Method A.1; read-across MDEA-Esterquat C16-18 and C18 unsatd.).

The boiling point of MDEA-Esterquat C16-18 and C18 unsatd. could not be determined up to a temperature of 250°C at 1013 hPa (OECD Guideline 103 and EU Method A.2; read-across MDEA-Esterquat C16-18 and C18 unsatd.).

The density and relative density (D20/4) of MDEA-Esterquat C16-18 and C18 unsatd. were determined to be 1.04 g/cm³ and 1.04 (at 20°C each), respectively (OECD Guideline 109 and and EU Method A.3; read-across MDEA-Esterquat C16-18 and C18 unsatd.).

According to REACH regulation (Annex VII, 7.14, column II), testing for particle size analysis is not required for those substances which are marketed or used in a non solid or non granular form.

According to REACH regulation (Annex XI, 2.), the vapour pressure does not need to be determined if the measurement is technically not feasible due to the substance properties. MDEA-Esterquat C18 satd. is an ionic solid at standard conditions (20°C, 1013 hPa), therefore a very low vapour pressure is to be expected. According to OECD guideline 104 vapour pressures lower than 1E-05 Pa cannot be determined.

According to REACH regulation (Annex XI, 2.), a 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. In the EU RAR 'DODMAC' (CAS 107 -64 -2), a chemical structurally similar to MDEA-Esterquat C18 satd., a measured log Kow=3.8 is reported.

The water solubility of the source substance MDEA-Esterquat C16-18 and C18 unsatd. was estimated to be 17.6 mg/L at 19.7°C based on the results of turbidity measurements (Method 2 of ASTM International E 1148 – 02); according to the classification scheme, the test substance can be regarded as slightly soluble in water.

The surface tension of the source substance MDEA-Esterquat C16-18 and C18 unsatd. was investigated in a study conducted according to OECD Guideline 115 and EU Method A.5. A mean surface tension (5-9 measurements) of 68.3 mN/m at 20°C was determined. The result in this test is not in line with the expected surface tension behaviour of the test substance. Cationic surfactants carrying two C18 alkyl chains are designed to possess surface active properties and typically exhibit surface tension values as low as 27 mN/m (depending on the area per molecule) when studied on a Langmuir film balance. Therefore due to the intrinsic properties (crystallization) of this double-chain cationic amphiphile at temperatures below the melting point no reliable results were obtained using the ring method. At temperatures of 20°C, the inner-molecular mobility of the fatty acid C-chains is hindered. Corresponding to this hinderance, on the one hand, the time to reach solubilisation equilibrium is long and on the other hand, there is a tendency to form vesicles.

According to REACH regulation (Annex XI, 1.), a test for determination of the flash point is scientifically not necessary, because the flash point refers to liquids (Reach R7.1.9). The test item is a solid at ambient temperature. Therefore determination of the flash point is not required.

The source substance MDEA-Esterquat C16-18 and C18 unsatd. proved to be not self-ignitable between 20°C and the melting temperature (54°C; EU Method A.16). The source substance MDEA-Esterquat C16-18 and C18 unsatd. is not highly flammable.

According to the REACH regulation (Annex VII, 7.11, column II), the study on explosiveness does not need to be conducted, if the substance does not contain chemical groups indicating explosive properties.

According to REACH regulation (Annex VII, 7.13, column II), testing of MDEA-Esterquat C18 satd. for oxidising properties does not need to be conducted, as the substance does not contain any structural groups known to be correlated with a tendency to react exothermically with combustible material.

 

Endpoint specific justification for read-across (physical and chemical properties)

For more details on substance identity , please refer also to the general justification for read-across given in chapter 5 of the CSR and attached as pdf document to section 7 of the IUCLID file.

Substance identities

The target substance MDEA Esterquat C18 satd. is a monoconstituent substance composed of diesters of saturated C18 fatty acids (IV < 1) with MDEA (Methyldiethanol amine) as amine backbone.

The first source substance MDEA Esterquat C16-18 and C18 unsatd. is a structurally similar UVCB substance composed of diesters of the long chain fatty acids C16, C18 and C18 unsaturated (iodine value, IV < 25) with MDEA (Methyldiethanol amine) as amine backbone

The second source substance DODMAC (Dimethyldioctadecylammonium chloride) is a structurally similar substance composed of C16 and C18 alkyl chains bound to a quaternised and dimethylated amine function.

 

Source substances

Target substance

 

MDEA-Esterquat C16-18 and C18 unsatd.

DODMAC (DHTDMAC)

MDEA Esterquat C18 satd.

CAS number

1079184-43-2

61789-80-8

67846-68-8

EC number

620-174-7

263-090-2

267-382-0

Fatty Acid

C16-18, C18’ (IV < 25)

C16-18

C18 (IV < 1)

Chain length distribution

<C16 <7%

 

C16, 16‘, 17 26-35%

C18 42-52%

C18‘ 15-20%

C18‘‘, 18‘‘‘ </= 1.5%

>C18 </= 2%

C12: </=2 %

C14: 1 - 5 %

C16: 25 - 35 % C18: ca. 65 %

 

 

C 20: </=2 %

 

 

C16 8%

C18 92%

Amine

Methyldiethanol amine

Dimethyl amine

Methyldiethanol amine

Anion

Chloride

Chloride

Chloride

 

Structural similarity

a. Structural similarity and functional groups

The target substance, MDEA Esterquat C18 satd., consists of an amine backbone (MDEA = Methyldiethanolamine) esterified with long chain fatty acid C18 saturated (IV < 1). The main reaction product is the dialkylester compound, next to that a smaller amount of the monoalkylester is formed. The amine function is quaternised with two methyl groups. The counter ion is Chloride.

The first source substance, MDEA-Esterquat C16-18 and C18 unsatd., consists of the same amine backbone (MDEA = Methyldiethanolamine) but esterified with a mixture of the long chain fatty acids C16, C18 and C18 unsaturated (IV < 25). Similar to MDEA Esterquat C18 satd. the main reaction product is the dialkylester compound (83-87%), next to that small amounts of the monoalkylester (4.5-8%) may be formed. The amine function is quaternised with two methyl groups. The counter ion is Chloride.

The source substance DODMAC (Dimethyldioctadecylammonium chloride) is one of the active components of the technical product DHTDMAC (dihydrogenated tallow alkyl dimethyl ammonium chloride). DHTDMAC consists of about 65% C18 (DODMAC) and 25-35% C16 and bound to a quaternised and dimethylated amine function. The counter ion is again Chloride.

 

Figure 1: Structures of the target substance MDEA Esterquat C18 satd. and the source substances MDEA-Esterquat C16-18 and C18 unsatd. and DODMAC (see attached image file)

b. Differences

There are small differences in fatty acid chain length distribution (additional shorter and less saturated fatty acid chains in the first source substance MDEA-Esterquat C16-18 and C18 unsatd.) between the target substance and the first source substance MDEA-Esterquat C16-18 and C18 unsatd. which could be relevant for bioavailability and may be of relevance for local effects but are not considered to be of great relevance for the physical chemical properties.

The target and the first source substance have a methyldiethanol amine backbone whereas the second source substance DODMAC contain a dimethyl amine. The main difference of these two chemical structures is that the target substance MDEA Esterquat C18 satd. and the first source substance MDEA Esterquat C16-18 and C18 unsatd. have, in contrast to the second source substance DODMAC, two polar ester moieties which are susceptible to hydrolysis and/or degradation. This is of relevance for the environmental fate and the toxicokinetic behaviour but is not considered to have a great influence on the partition coefficient. 

Comparison of physicochemical properties

 

Source substances

Target substance

Endpoints

MDEA-Esterquat C16-18 and C18 unsatd.

DODMAC

MDEA Esterquat C18 satd.

Molecular weight

697 g/mol

586.5 g/mol

702.6 g/mol

Physical state at 20°C / 1013 hPa

solid (waxy)

solid

solid (waxy)

Melting point

OECD guideline 102; RL 1; GLP

 

54°C

 

 

 

72-122°C

read-across MDEA-Esterquat C16-18 and C18 unsatd.

Boiling point

OECD guideline 103; RL 1; GLP

 

No boiling up to 250°C

 

 

Decomposition at 135°C

read-across MDEA-Esterquat C16-18 and C18 unsatd.

Surface tension

OECD Guideline 115; RL2, GLP

 

68.3 mN/m at 20°C - not in line with the expected surface active behaviour of the substance (see discussion below table)

 

 

 

11 mN/m at 20 °C (saturated solution; method: film balance)

read-across MDEA-Esterquat C16-18 and C18 unsatd.

Water solubility

ASTM International E 1148 – 02, RL1, GLP

 

 

17.6 mg/L at 19.7°C

 

 

 

 

2.7 mg/L

read-across MDEA-Esterquat C16-18 and C18 unsatd.

Log Kow

read-across DODMAC

3.8

read-across DODMAC

Vapour pressure

 7.33E-18 Pa at 25°C (EpiSuite estimation)

negligible because of the salt character

7.33E-18 Pa at 25°C (EpiSuite estimation)

Auto flammability

EU Method A.16, RL 1, GLP

 

not self-ignitable between 20°C and the melting temperature (54°C)

No data

read-across MDEA-Esterquat C16-18 and C18 unsatd.

Flammability

EU Method A.10, RL 1, GLP

 

not highly flammable

No data

read-across MDEA-Esterquat C16-18 and C18 unsatd.

 

The molecular weights of the target and source substances are in a comparable range. Experimental data regarding physical chemical properties are not available for MDEA Esterquat C18 satd. Therefore for most endpoints a read-across approach from the structurally very similar MDEA-Esterquat C16-18 and C18 unsatd. was applied.

As the target substance MDEA Esterquat C18 satd. is the main component of the source substance MDEA-Esterquat C16-18 and C18 unsatd. which is composed of 42-52% esters between MDEA and C18 satd. fatty acids (see table substance identities) no relevant differences are expected in physical chemical properties. If any, the amount of shorter alkyl chains (26-35% C16) and the higher grade of unsaturation (IV < 25) in the source substance could have a marginal effect on the boiling point and the water solubility. The target substance MDEA Esterquat C18 satd. can be expected to have a marginally higher boiling point and a negligibly lower water solubility.

The result from the study on surface tension with the source substance MDEA-Esterquat C16-18 and C18 unsatd. was not in line with the expected surface tension behaviour of this kind of test substances. Cationic surfactants carrying two long alkyl chains, such as MDEA-Esterquat C16-18 and C18 unsatd. and MDEA Esterquat C18 satd. are designed to possess surface active properties and typically exhibit surface tension values as low as 27 mN/m. However, at temperatures of 20 °C, the inner-molecular mobility of the fatty acid C-chains is hindered. Corresponding to this hinderance, on the one hand, the time to reach solubilisation equilibrium is long and on the other hand, there is a tendency to form vesicles.

Data on log Kow are not available for the source substance MDEA Esterquat C16-18 and C18 unsatd.. In this case a read-across approach from the structurally similar second source substance DODMAC was applied, resulting in a log Kow of 3.8.

Both source substances have comparable physical chemical properties which strengthen the read-across approach.

 

Conclusion

The structural similarities between the source and the target substances support the read-across hypothesis. As the source substance MDEA-Esterquat C16-18 and C18 unsatd. is also mainly composed of esters between MDEA and C18 satd. fatty acids similar to the target substance MDEA Esterquat C18 satd. and because of the great structural similarity of the C18 satd. fatty acid to the additionally present fatty acids (C16, C18 unsatd.) there is no reason to believe that there are great differences in physical chemical properties between the target and the first source substance.

For the endpoint partition coefficient a read-across approach to the second source substance DODMAC was applied. Because of the structural similarity the log Kow of the target substance MDEA Esterquat C18 satd. is expected to 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 MDEA Esterquat C18 satd. 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