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Flash point

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Endpoint:
flash point of flammable liquids
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Endpoint:
flash point of flammable liquids
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The source substance is the racemic form of the target substance d-tetramethrin. Tetramethrin does consist of 50% d- and l-form, and both do exist as cis and trans isomers. Hence, the target substance does consist of d-cis-tetramethrin, d-trans-tetramethrin, l-cis-tetramethrin and l-trans-tetramethrin, whereas the target substance only contains the first two (i.e. d-cis-tetramethrin, d-trans-tetramethrin).
Both, the source as well as the target substance, do have a cis/trans ratio of approximately 1/4 and obviously do share same molecular mass and other properties. Thus, the source substance by definition does contain ~50% of the d-form and the l-form is not expected to be significantly different with respect to its flammability behaviour. However, as the racemic form is solid, compared with the d-tetramethrin being liquid at 20 °C, the study performed using the racemic form to determine flammability was according the method A.10 for solid substances. In a pre-test according to method A.10, the test substance was exposed to the flame of a Bunsen burner for 2 minutes. Neither did the test item tetramethrin techn. ignite, nor did it propagate the flame. Thus, no further testing was required and the substance is considered non-flammable. Thus, it can be reasonably assumed that the liquid d-tetramethrin will not be critical with respect to flash point temperature.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The d-tetramethrin with a purity > 80 % does contain its corresponding l-form as an impurity in the range of < 7%, other impurities from the manufacturing process are individually below 1% (w/w) each. The source substance that has been tested was having a purity of approx. 98% as tetramethrin with a cis/trans ratio of 1/4 and a d-form/l-form ratio of ~50/50.
3. ANALOGUE APPROACH JUSTIFICATION
Source and Target substance do share identical structure and molecular weight, only differentiating by the fact that the source substance is a racemic mixture, whereas the target substance represents almost pure d-form. Thus, physico-chemical parameters, not being affected significantly by stereochemistry, are fully comparable, thus justifying using available data on flammability and auto-ignition properties on the racemic form for supportive read-across to the d-enantiomer.
4. DATA MATRIX
Composition comparison
D-tetramethrin (target) tetramethrin (source)
D-trans tetramethrin 70 - 80% 40 – 50%
D-cis tetramethrin 10 - 20% 7 – 11 %
L-trans tetramethrin 0 – 5% 35 – 40%
L-cis tetramethrin 0 – 2% 7 – 11%
Reason / purpose:
read-across source
Atm. press.:
1 atm
Remarks on result:
other: could not be ignited by Bunsen burner

Description of key information

The study does not need to be conducted as the racemate, (mixture of D- and L-form) had been tested for flammability according to method A.10 and was found not being flammable (substance did melt but did not ignite when treated with a Bunsen-burner flame).

The racemic form of the substance (50:50 mixture of D-tetramethrin and L-tetramethrin) has a melting point of 72 - 74 °C and thus determination of the flash point is not required for the racemic form. However, when testing for flammability of solids has been performed (according to method A.10) it could be shown that the substance did melt, but did not ignite and thus was considered non-flammable (see supportive study in section Flammability). Consequently, it can be concluded, that the D-tetramethrin (50% of racemic form) also is non-flammable. Furthermore, this is supported by the very low vapour pressure of racemic tetramethrin, being well below 1 mPa.

Key value for chemical safety assessment

Additional information