4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study was conducted according to an appropriate EU test method but not compliant with GLP.

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Version / remarks:

92/69/EEC

GLP compliance:

no

Type of method:

static method

Key result

Test no.:

#1

Temp.:

20 °C

Vapour pressure:

9 Pa

Key result

Test no.:

#2

Temp.:

25 °C

Vapour pressure:

12 Pa

Data:

Vacuum before measurement: 0.02 mmHg

 

Vapour pressure of the test substance

S/N	Temperature	Pressure
	°C	mm DBP
1	20.0	1
2	30.9	2
3	41.4	3
4	50.9	4
5	60.0	9
6	70.8	17
7	80.2	23

 

Calculation:

The readings (mm DBP) from the U-tube manometer were converted into pressure units by the following equations.

p =ƿ.g.Δh

 

where

p = vapour pressure/Pa

ƿ = 1.045 g/cm3 (density of DBP at 22°C)

g = 9.81 m/s2

Δh = height of fluid column/mm

 

S/N	Temperature	Pressure
	°C	Pa
1	20.0	10
2	30.9	20
3	41.4	31
4	50.9	41
5	60.0	92
6	70.8	174
7	80.2	245

 

The data was fitted to a vapour pressure equation of the Antoine-type:

ln P = A - B / (T - C)

 

where P is the pressure in kPa, and T is the temperature in K.

A = 18.15

B = 8230

C = -67

 

Using the equation, the vapor pressure at a specified temperature in the range 290 - 360 K can be calculated. The results are 9 Pa 20°C and 12 at 25°C.

Conclusions:

Vapour pressure values of 9 Pa at 20°C and 12 Pa at 25°C were obtained for the substance in a reliable study conducted in accordance with a standard guideline (static method). It was not conducted under GLP.

Description of key information

Vapour pressure [4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane]: 9 Pa at 20°C and 12 Pa at 25°C (EU Method A.4)

 

Vapour pressure [(3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol]: 6.3E-12 Pa at 25°C (QSAR)

 

Vapour pressure [ethanol]: 7910 Pa at 25°C

Key value for chemical safety assessment

Vapour pressure:

9 Pa

at the temperature of:

20 °C

Additional information

Measured vapour pressure values of 9 Pa at 20°C and 12 Pa at 25°C were obtained for the substance using a static method in accordance with EU Test Method A.4 but not in compliance with GLP. The result is considered to be reliable and is selected as key study. This value is supported by a vapour pressure value of 10 Pa at 20°C which was reported for the substance in a secondary source to which reliability cannot be assigned.

 

In contact with water, the substance will undergo hydrolysis at a moderate rate to form (3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol and ethanol.

 

The silanol hydrolysis product, (3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol has a predicted vapour pressure of 6.3E-12 Pa at 25°C using a validated QSAR estimation method.

 

Ethanol has a reported vapour pressure of 7910 Pa at 25°C (Daubert and Danner (1985)).

 

Reference:

Daubert, T E and Danner R P (1985).Physical and Thermodynamic properties of Pure Chemicals. Data Compilation