Imidazolium compounds, 2-C17-unsatd.-alkyl-1-(2-C18-unsatd. amidoethyl)-4,5-dihydro-N-methyl, Me sulfates

Endpoint summary

Additional information

At 20°C and 101.3 kPa, Oleic-acid based IQAC, DMS quaternised is a highly viscous gel – like to paste-like dark yellow hazy liquid. A melting point for the test substance could not be identified. Instead, the substance's viscosity continually increased over a wide temperature range reaching an almost solid state at -40 °C. The cited melting range is therefore the reported pour point of the test substance according to DIN ISO 3016, which is 5°C ± 3°C. The DSC curves showed a large endothermic peak in the range between 293 -337 °C. The boiling point was therefore identified as the temperature where the observed signal is at its peak, 317 °C.

The density of the test substance is 0.976 g/cm³ at 40 °C, measured using an aerometer, and 0.9832 g/cm³ at 25 °C, measured using a Hubbard pycnometer. Testing of the substance for particle size distribution (granulometry) is scientifically not necessary, as the substance is a liquid. Testing of the vapour pressure is scientifically not justified, as the substance has a high molecular weight of 733 g/mol and is ionic. The vapour pressure is expected to be immeasurable low. This is supported by the EPIWIN calculation resulting in a vapour pressure of 1.41 x 10E-21 hPa at 25°C.

The log Kow of Oleic-acid based IQAC, DMS quaternised was calculated from experimentally derived solubility in water whereas the total solubility in n-octanol was not experimentally approved. Instead an arbitrarily value of >2000 mg/l for the solubility in n-octanol was choosen and thus an log Kow of > 5.7 was calculated.

According to the experience of the registrand, it is questionable whether a logKow can be determined experimentally at all for this substance having properties as self emulsifying, high affinity to charged surfaces and time-delay in reaching equilibrium from solutes.

A calculated log Kow by EPIWIN should not be used for the assessment, because Oleic-acid based IQAC, DMS quaternised is ionic. EPIWIN does not take into account the ionic structure of the substance.

The recalculation (with linear correlation equation as stated in guidance) of the logKow from the BCF value of 10.7 (see 4.3), the log Kow should be lower than 5.7. However correlation between log Kow and BCF is not linear for substances with high molecular weight. The database for the correlation between BCF and logKow doesn't contain sufficient substances containing quaternary structures. Therefore the lower limit of the n-octanol/water-partition coefficient (log Know = 5.7) was used for the assessment as a conservative approach.

According to the method EEC A.9, the flashpoint of the test substance is 186.5 ±1°C at 1013 hPa. In another test performed according to ISO 3679 the flash point of Oleic-acid based IQAC, DMS quaternised was determined to be 35.0°C ± 0.5°C. This study is not regarded as relevant, as the product tested contained isopropanol to a considerable amount. The low flash point is attributed to isopropanol. From a test of the read across substance Partially unsaturated IQAC, DMS quaternised, it can be concluded that Oleic-acid based IQAC, DMS quaternised is not auto-flammable. Oleic-acid based IQAC, DMS quaternised did also not ignite when exposed to an ignition source. The substance showed neither pyrophoric properties nor the potential to form flammable gases when in contact with water or humid air. The appraisal of the molecular structure indicates no risk with respect to pyrophoric properties or the potential of evolving flammable gases in contact with water or humid air. In addition, during the conduction of other tests (e. g. water solubility) the test item did not show any spontaneous ignition or formation of flammable gases. According to the reactive groups, the oxygen balance and the calorimetric test, the test item is not to be classified as explosive material and no experimental determination according to the EC test guideline A.14 has to be performed. This judgement is in respect to classification. The substance has no oxidising properties, as the substance does not contain any structural groups known to be correlated with a tendency to react exothermally with combustible material. The substance is stable in organic solvents. In water, the substance is hydrolytically unstable (half-life less than 12 hours).

Oleic-acid based IQAC, DMS quaternised is an ionic salt and dissociates rapidly in water to form the organic quaternary imidazolium cation and the inorganic sulphate anion. Since no analytical method is available for the determination of the undissociated test item, the conduct of further experimental verification was not considered to be technically or scientifically feasible. Oleic-acid based IQAC, DMS quaternised is a highly viscous gel – like to paste-like liquid. Therefore testing oft the viscosity is technically not feasible. READ-ACROSS HYPOTHISIS AND JUSTIFICATION

Hypothesis:

The physicochemical profile is expected to be similar for the target substance oleic-acid based IQAC, DMS quaternised when compared to the source substance partially unsaturated IQAC, DMS quaternised. Read-across is expected to be reliable. 

Short summary:

This read-across is based on the hypothesis that source and target substances, both Imidazolium quaternary ammonium compounds (IQACs)have similar physic-chemical properties, based on the followingunderlying identical generic structure. There are only minor differences in carbon chain length (more C18 than C16 vs. mainly C18) and degree of saturation of the fatty acid moiety present in the structure of source and target substance.

This prediction is supported by physicochemical data on the substances themselves. Associated Robust study summaries are provided in the Technical Dossier.

Both, target and source chemicals are UVCB substances, the production process includes the same steps, and raw materials with exception of the source of fatty acid are comparable.

The underlying generic structure of the two main constituents of both substances, which represents 90 – 95 % of the UVCBs, is identical, only varying in the fatty acid chain length and degree of saturation. Also the percental distribution of the main constituents is comparable. Therefore, the source and target substance share structural similarities with common functional groups, only varying in carbon chain length and degree of saturation.

Moreover, the fatty acid site chains are chemically simple structures which have no alerts for toxicity, because they occur naturally and their metabolism via beta oxidation is well known.

Considering that the source and target substances have identical generic structures of main constituents and similar physicochemical properties, read-across for the endpoints auto flammability, flammability and explosive properties is considered an appropriate adaptation to meet the standard information requirements according to REACH Regulation. 

Detailed information on substance identity of source and target substance can be found in the “Justification for read-across - toxicological information”, provided in a separate document in chapter 13 of Technical Dossier.

PHYSICOCHEMICAL PROPERTIES

Table: Information on the physicochemical properties

Corresponding standard information requirement	Source substance partially unsaturated IQAC, DMS quaternised	Target substance oleic-acid based IQAC, DMS quaternised
Appearance	“solid” Solid paste	“liquid” highly viscous liquid
Boiling point	310°C	317 °C
Melting point	76 °C	5 °C
Water solubility	Slow stirring method: 2.6 mg/L at 22 °C	Slow stirring method: 2.2 mg/L at 20 °C
Partition coefficient n-octanol/water	Questionable whether a logKow can be experimentally determined at all for this group of substances	Questionable whether a logKow can be experimentally determined at all for this group of substances
Vapour pressure	EPI-Suitev4.00 calculation: 7.5 x 10E-22 Pa at 25°C Ref.:	Waiving supported by EPIWIN calculation: 1.41 x 10E-21 hPa at 25°C Ref.:
Flash point	Waiving; refers to liquids – substance is a solid paste	Closed cup method (Pensky - Martens) 186.5°C at 1013 hPa

 

Physicochemical data show that the physicochemical profiles of the target and source substances are comparable as outlined in the table. The structural differences, the minor deviance in chain length and degree of saturation in the fatty acid moiety, do not essentially affect the physicochemical properties as shown by the results of respective experimental studies.

None of the substances is volatile. The water solubility of both IQACs is in the same range as well as the boiling point.

The melting point and the corresponding appearance are different. Due to the higher degree of unsaturation of the fatty acid moiety, the target substance is a liquid with a melting point of 5°C, whereas the source substance is a solid paste with a melting point of 76 °C. However, these differences are considered to have no impact on read-across for systemic endpoints, because in those studies the test substance is administrated in soluble form.

The structural similarities between the source and the target substances are the basis for the read-across hypothesis. Adequate, reliable and available scientific information indicates that the source and target substances have similar physicochemical properties and thus support the read-across hypothesis.

In conclusion the results obtained from source substance (partially unsaturated IQAC, DMS quaternised) are considered a reliable source to fulfil the information requirements of Annex VII, 7.10 (flammability), 7.11 (explosive properties) and 7.12 (self-ignition temperature).