1,1-dimethylurea

Endpoint summary

Description of key information

Appearance / physical state / colour

In several Guideline studies and an MSDS 1,1 -Dimethylurea is characterised as with solid with an amine-like odour.

Melting point

Two melting point of 1,1 -Dimethylurea was determined in two independent tests:

1) The melting range of 1,1 -Dimethylurea was determined according to “Capillary tube in a metal block” inOECD 102 - “Melting Point /”.The melting range was determined twice, and a new capillary tube filled with the sample was used each time.Based on the results of this test the melting range of 1,1 -Dimethylurea was 181.4 - 183.2 °C.

2) The melting temperature of 1,1 -Dimethylurea was measured by Differential-Scanning-Calorimetry. The test was conducted according to EC 440/2008 A.1. The substance showed a melting temperature of 182 °C.

According to this results the melting point of 1,1 -Dimethylurea was defined to be 182 °C.

Boiling point

The study does not need to be conducted because the substance 1,1-Dimethylurea decomposes before boiling.

Density

Using the pycnometer method, a density of 1.241 g/cm3 = 1241 kg/m3 (20°C) was measured. This value is the mean of two independent determinations.

Particle size distribution

The particle size of 1,1 -Dimethylurea was determined according to ISO 2926 (2005). A certain mass of the sample was sieved according to decreasing aperture size, from 710 μm to 425 μm , 300 μm, 212 μm, 125μm and 40 μm. Each mass of the separate fractionsretained on the sievewas weighed and the mass distribution of the particle sizes was calculated.

Particle Size Distribution of 1,1-Dimethylurea:

> 710 µm: 5.80 %

425 - 710 µm: 34.49 %

300 - 425 µm: 21.66 %

212 - 300 µm: 15.43 %

125 - 212 µm: 11.43 %

40 - 125 µm: 8.50 %

< 40 µm: 1.48 %

Vapour pressure

The purpose of this study was the determination of the vapour pressure of the test substance 1,1 -Dimethylurea according to OECD 104 ("Vapour Pressure") and EU Method A.4. ("Vapour pressure: Effusion method"). The method is based on the estimation of the mass of the test item following out per unit of time of a Knudsen cell in form of vapour, through a micro-orificr under ultra-vacuum conditions.

The following vapour pressure values for the test substance 1,1-Dimethylurea were extrapolated from the experimental data:

Vapour Pressure (20 °C) = 4.4 x 10^-3 Pa

Vapour Pressure (25 °C) = 8.2 x 10^-5 Pa

Vapour Pressure (50 °C) = 1.3 x 10^-1 Pa

Partition coefficient

In a study according to OECD 117 the Partition Coefficient (n-octanol/water) of 1,1-Dimethylurea was tested and determined as log Pow = -4.6.

Water solubility

In a study according to OECD 105 the water solubility of 1,1-Dimethylurea was determined to be 143.1 g/L (20 °C, pH 9.4).

Flash point

In accordance with column 2 of REACH Annex VII, the study does not need to be conducted as 1,1 -Dimethylurea is solid.

The flash point is a key measure of the flammability of a liquid. It measures the lowest temperature at which the vapour/air mixture above the liquid can be ignited.

Auto flammability

No auto-ignition of deposited dust of 1,1 -Dimethylurea occurred on hot surfaces until 360°C.

The autoflammability temperature of dispersed dust of 1,1 -Dimethylurea was tested to be 425 °C.

Furthermore the relative self-ignition temperature of 1,1 -Dimethylurea was determined in a test according to EC Regulation No.440/2008 Annex A.16. The test indicates that the relative self-ignition temperature of 1,1 -Dimethylurea lies above its melting point.

Flammability

Different tests were carried out in order to estimate the flammability of 1,1-Dimethylurea:

One test was carried out according to 33.2.1.4 in "Recommendations on the transport of dangerous goods - Manual of Tests and Criteria (ST/AC.10/11/Rev.5), United Nations (2009)." The burning rate test showed that the sample of 1,1-Dimethylurea was ignited within 2 min. After removal of ignition, the sample did not propagate combustion either by burning with flame or smoldering along 200 mm of the train within the 2 min. Therefore 1,1-Dimethylurea is not a flammable solid.

In a test according to EG No. 1907/2006 A.10 1,1 -Dimethylurea showed burning rates, that does not lead to classification as highly flammable.

1,1-Dimethylurea is considered to be non highly flammable.

Also three tests were conducted according to guidelines similar to guideline A.10.

1,1 -Dimethylurea was dried before testing. The dried1,1 -Dimethylurea could be ignited by the 1000 °C hot platin wire, which was dipped for 5 seconds into the dried substance. Local burning of the melted test substance occured with only minor expansion ("Bewertungszahl 3").

In a second test approx. 200 mg of 1,1 -Dimethylurea were put into a flat iron bowl and heated with an open gas flame burner for 10 - 15 seconds. 1,1 -Dimethylurea was melting but could not be ignited ("Bewertungszahl 1").

In a third test approx. 150 mg of 1,1 -Dimethylurea and a 1:1 mixture of potasium nitrate and 1,1 -Dimethylurea were put into a red heated iron bowl for 60 seconds.1,1 -Dimethylurea could be ignited and the melted test substance burns off quickly ("Bewertungszahl 5"). Also a mixture of potassium nitrate and 1,1 -Dimethylurea showed the same reaction ("Bewertungszahl 5").

Explosiveness

The substance 1,1-Dimethylurea does not contain any chemical groups present in the molecule which are associated with explosive properties.

 Furthermore a study was conducted according to a slightly different method than guideline A.14 and investigated the mechanical sensitivity to friction and shock of 1,1 -Dimethylurea. The thermal sensivity was not investigated. The results show no explosive properties of 1,1 -Dimethylurea as the test substance is not sensitive to shock and friction.

Oxidising properties

The substance 1,1 -Dimethylurea does not contain halogen atoms. The oxygen atoms are not chemically bonded to nitrogen. Therefore, the substance is considered incapableof reacting exothermically with combustile materials and does not have to be classified.

sified.y does not need to be conducted as the substance 1,1-Dimethylurea does not contain halogen atoms.








  
  
  












  



Therefore, the substance is considered incapable of reacting exothermically with combustible materials.