1,1-dimethylurea

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20/01/2016 - 11/05/2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

GLP compliance:

yes (incl. QA statement)

Type of method:

effusion method: vapour pressure balance

Specific details on test material used for the study:

- Name of test material (as cited in study report): 1,1-Dimethylharnstoff, N,N-Dimethylharnstoff
- Physical state: solid

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: AlzChem AG, Batch 534201
- Expiration date of the lot/batch: 31/12/2017
- Purity test date:17/12/2015

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Ambient temperature (10-30 °C), dry, protected from light

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test item was tested as received. No further preliminary treatment such as drying or milling was performed.

Temp.:

20 °C

Vapour pressure:

0.004 Pa

Key result

Temp.:

25 °C

Vapour pressure:

0.008 Pa

Temp.:

50 °C

Vapour pressure:

0.13 Pa

The vapour pressure was measured in the temperature range of 30 °C to 80 °C. The measured vapour pressures at the corresponding temperatures are listed in Table 1.

Table1: Measured vapour pressures and corresponding temperatures

Temperature / °C	Vapour pressure / hPa
30	1.6 × 10^-4
40	4.2 × 10^-4
50	1.3 × 10^-3
60	3.8 × 10^-3
70	1.0 × 10^-2
80	2.2 × 10^-2

The values for 20, 25 and 50 °C are calculated, using the Antoine constants A, B and C as shown in Table 2.

Table 2: Antoine parameters and extrapolated vapour pressures

T / °C	p / hPa	log (p/hPa) = A + B/(C+T[°C])
20	4.4×10^-5	A =	11.61755
25	8.2×10^-5	B =	-4682.45
50	1.3×10^-3	C =	273.15

Conclusions:

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

Executive summary:

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

Description of key information

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

Key value for chemical safety assessment

Vapour pressure:

0.008 Pa

at the temperature of:

25 °C