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Physical & Chemical properties

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Description of key information

Additional information

Appearance/physical state/colour:

The physical state of the test material at room temperature has been addressed on a weight of evidence basis using two GLP compliant study reports. Denton (1994) reports the test material to bea white crystalline powder at room temperature and Baltussen (2012) reports the test material as a white powder at room temperature. Both studies were performed to GLP and in line with relevant test guidelines and have therefore both been assigned a reliability score of 1 according to the principles for assessing data quality set out in Klimisch (1997).

Melting point:

The melting/freezing point of 3,5-Dimethylpyrazole was determined to be 107 ºC in a key study (Baltussen, 2012) performed to OECD 102, EU method A.1 and EPA OPPTS 830.7200.

Boiling point:

The boiling point of 3,5-Dimethylpyrazole was determined to be 220 ºC in a key study (Baltussen, 2012) performed according to OECD 103, EU method A.2 and EPA OPPTS 830.7220.

Density:

The density of 3,5-Dimethylpyrazole was determined to be 1.14 g/cm³ in a key study (Baltussen, 2012) performed according to OECD 109, EU method A.3 and EPA OPPTS 830.7300.

Particle size:

The particle size of 3,5-Dimethylpyrazole was determined in a key study (Livingston, 2012) to have a MMAD (mass median aerodynamic diameter) of 268.990 µm, median diameter of 251.932 µm with a geometric standard deviation of between 1.482 and 1.486. The study was performed to GLP and the standardised guidelines; particle size analysis: CTL SOP No. 417; ISO 13320: 2009; CIPAC MT 187 and in consideration of the OECD guideline 110.

Vapour pressure:

The vapour pressure of 3,5-Dimethylpyrazole was determined to 0.37 Pa at 20ºC in a key study (Baltussen, 2012) performed according to OECD 104, EU method A.3 and EPA OPPTS 830.7950.

Partition coefficient:

The partition coefficient of 3,5-Dimethylpyrazole was determined to be Pow 1.4 x 10^2 and log Pow 2.1, in a key study (Baltussen, 2012) performed according to OECD 1147, EU method A.8 and EPA OPPTS 830.7570. A QSAR prediction has also been included as supporting data.

Water solubility:

The water solubility of 3,5-Dimethylpyrazole was determined to be very soluble, 28.9 g/L at 20 ºC, in a key study (Baltussen, 2012) performed according to OECD 105, EU method A.6 and EPA OPPTS 830.7840.

Surface tension:

In accordance with Column 2 adaptation statement of REACH Annex VII, information requirement section 7.6, this study does not need to be conducted if based on the structure, surface activity is not expected nor is it a desired property of the material.

Flash point:

In accordance with Section 2 of REACH Annex XI, information requirement section 7.9, this study does not need to be conducted based on the physical state of the substance. Flash point is a measure of the flammability of a liquid, testing has therefore been omitted as it is not technically possible to conduct the study on a solid.

Auto flammability:

In accordance with Column 2 adaptation statement of REACH Annex VII, information requirement section 7.12, this study does not need to be conducted for solids if the melting point is ≤ 160 ºC. The melting point of the test material is 107.5 ºC therefore testing has been omitted.

Flammability:

The flammability of 3,5-Dimethylpyrazole was determined by performing the burn test (Baltussen, 2012) according to GLP and the standardised guidelines EU method A. 10 and UN Test N.1. Negative results can be predicted for pyrophoric properties and flammability in contact with water, based on the test materials chemical structure. Thus the test material is considered to be non flammable accordingly.

Explosiveness:

An expert report (Carling & Liney, 2012) based on a structural evaluation of the test material has been provided as the key study. The report concludes that the test material does not contain explosive properties and thus further testing is not required.

Oxidising properties:

An expert report (Carling & Liney, 2012) based on a structural evaluation of the test material has been provided as the key study. The report concludes that the test material does not contain oxidising properties and thus further testing is not required.

Stability in organic solvents:

In accordance with Column 1 of REACH Annex IX, information requirement 7.15, this study is only required if stability of the substance is considered to be critical. Stability in solvents is not critical for this substance.

Dissociation constant:

The dissociation constants (pKa’s) of the substance 3,5-Dimethylpyrazole were estimated using the pKalc function of the PALLAS estimation software program (CompuDrug, version 3.6.2.1) (QSAR). The test material was predicted to be pKa 4.17, according to PALLAS version 3.6.2.1.

Viscosity:

In accordance with Section 2 of REACH Annex XI, information requirement section 7.17, this study cannot be conducted on solid materials or gases. Furthermore according to ECHA Chapter 7 guidance, viscosity measurement is only relevant to liquids and thus testing has been omitted as this substance is a solid at room temperature.

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