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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2007-03-29 to 2007-04-01
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Version / remarks:
25 March 2006
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
isoteniscope
Key result
Test no.:
#1
Temp.:
25 °C
Vapour pressure:
2.3 Pa

Results

Run 1

LHS column (cm Hg)

RHS column (cm Hg)

Temperature (°C)

Vapour pressure (Pa)

Temperature (K)

Reciprocal Temperature (K)

Log VP

48.5

28.5

206.8

26664.47

479.95

0.002083550

4.425933016

48.2

28.8

205.5

25864.54

478.65

0.002089209

4.412704750

47.8

29.2

203.9

24797.96

477.05

0.002096216

4.394415964

47.4

29.6

202.4

23731.38

475.55

0.002102828

4.375323022

46.8

30.2

200.6

22131.51

473.75

0.002110818

4.345011108

46.4

30.6

199.1

21064.93

472.25

0.002117522

4.323560107

46.0

31.0

197.2

19998.36

470.35

0.002126076

4.300994279

45.5

31.5

195.6

18665.13

468.75

0.002133333

4.271031056

45.0

32.0

193.8

17331.91

466.95

0.002141557

4.238846372

44.8

32.2

192.1

16798.62

465.25

0.002149382

4.225273565

44.4

32.6

190.1

15732.04

463.25

0.002158662

4.196785027

43.9

33.1

188.0

14398.82

461.15

0.002168492

4.158326776

43.4

33.6

184.9

13065.59

458.05

0.002183168

4.116129096

43.0

34.0

183.1

11999.01

456.25

0.002191781

4.079145530

42.5

34.5

179.8

10665.79

452.95

0.002207749

4.027993007

42.2

34.8

177.8

9865.86

450.95

0.002217541

3.994134740

42.0

35.0

175.7

9332.57

448.85

0.002227916

3.970001060

 

The following regression was obtained by plotting log VP (Pa) versus 1/T (K)

Slope = -3234.627

Standard deviation = 25.332

Intercept = 11.173

Standard deviation in intercept = 0.054

The following vapour pressure relationship was obtained

Log VP (Pa) = -3234.627/Temp (K) + 11.173

 

Run 2

LHS column (cm Hg)

RHS column (cm Hg)

Temperature (°C)

Vapour pressure (Pa)

Temperature (K)

Reciprocal Temperature (K)

Log VP

52.5

24.5

217.7

37330.26

490.85

0.002037282

4.572061051

52.0

25.0

216.4

35997.04

489.55

0.002042692

4.556266784

51.5

25.5

214.5

34663.82

487.65

0.002050651

4.539876368

51.0

26.0

213.0

33330.59

486.15

0.002056978

4.522843029

50.2

26.8

211.4

31197.43

484.55

0.002063771

4.494118878

49.6

27.4

209.4

29597.57

482.55

0.002072324

4.471255995

49.0

28.0

207.6

27997.70

480.75

0.002080083

4.447122315

48.4

28.6

205.5

26397.83

478.65

0.002089209

4.421568210

47.8

29.2

203.5

24797.96

476.65

0.002097975

4.394415964

47.2

29.8

201.8

23198.09

474.95

0.002105485

4.365452268

46.2

30.8

198.5

20531.64

471.65

0.002120216

4.312423741

45.8

31.2

196.3

17465.07

469.45

0.002130152

4.289255876

45.2

31.8

194.0

17865.20

467.15

0.002140640

4.252007818

45.0

32.0

192.1

17331.91

465.25

0.002149382

4.238846372

44.6

32.4

190.7

16265.33

463.85

0.002155869

4.211262851

44.2

32.8

189.2

15198.75

462.35

0.002162864

4.181807871

43.8

33.2

187.8

14132.17

460.95

0.002169433

4.150208885

43.5

33.5

186.4

13332.24

459.55

0.002176042

4.124903020

43.2

33.8

183.4

12532.30

456.55

0.002190341

4.098030874

42.8

34.2

181.5

11465.72

454.65

0.002199494

4.059401471

42.5

34.5

179.6

10665.79

452.75

0.002208724

4.027993007

42.0

35.0

175.8

9332.57

448.95

0.002227420

3.970001060

41.8

35.2

173.6

8799.28

446.75

0.002238388

3.944446956

41.5

35.5

171.7

7999.34

444.85

0.002247949

3.903054271

 

The following regression was obtained by plotting log VP (Pa) versus 1/T (K)

Slope = -3200.501

Standard deviation = 22.069

Intercept = 11.102

Standard deviation in intercept = 0.047

The following vapour pressure relationship was obtained

Log VP (Pa) = -3200.501/Temp (K) + 11.102

Run 3

LHS column (cm Hg)

RHS column (cm Hg)

Temperature (°C)

Vapour pressure (Pa)

Temperature (K)

Reciprocal Temperature (K)

Log VP

48.8

28.2

206.2

27464.41

479.35

0.002086158

4.438770241

48.2

28.8

204.0

25864.54

477.15

0.002095777

4.412704750

47.5

29.5

201.8

23998.03

474.95

0.002105485

4.380175525

46.8

30.2

199.3

22131.51

472.45

0.002116626

4.345011108

46.1

30.9

196.2

20265.00

469.35

0.002130606

4.306746608

45.5

31.5

193.8

18665.13

466.95

0.002141557

4.271031056

45.0

32.0

191.8

17331.91

464.95

0.002150769

4.238846372

44.5

32.5

189.3

15998.68

462.45

0.002162396

4.204084266

44.0

33.0

186.7

14665.46

459.85

0.002174622

4.166295705

43.5

33.5

184.3

13332.24

457.45

0.002186031

4.124903020

43.2

33.8

182.1

12532.30

455.25

0.002196595

4.098030874

42.5

34.5

178.5

10665.79

451.65

0.002214104

4.027993007

42.2

34.8

176.0

9865.86

449.15

0.002226428

3.994134740

 

The following regression was obtained by plotting log VP (Pa) versus 1/T (K)

Slope = -3184.434

Standard deviation = 27.753

Intercept = 11.087

Standard deviation in intercept = 0.060

The following vapour pressure relationship was obtained

Log VP (Pa) = -3184.434/Temp (K) + 11.087

Summary of results

Run

Log [VP (25°C)]

1

0.324

2

0.368

3

0.406

Mean

0.366

Vapour pressure

2.323 Pa

 

Conclusions:
A vapour pressure value of 2.3 Pa at 25°C was determined by extrapolation from temperature range of 170 - 220°C for the substance in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP. The result is considered reliable.

Description of key information

Vapour pressure [3-trimethoxysilylpropyl methacrylate]: 2.3 Pa at 25°C (OECD 104)

Vapour pressure [3-(trihydroxysilyl)propyl methacrylate]: 1.2E-05 Pa at 25°C (QSAR)

Vapour pressure methanol: 12790 Pa at 20°C

Key value for chemical safety assessment

Vapour pressure:
2.3 Pa
at the temperature of:
25 °C

Additional information

A measured vapour pressure of 2.3 Pa at 25°C was determined by extrapolation from measurements in the temperature range of 170-220°C. The study was performed using the isoteniscope method in accordance with OECD Test Guideline 104 and in compliance with GLP. The result is considered to be reliable and selected as key study.

In other secondary sources to which reliability could not be assigned, vapour pressure values of approximately 1600 Pa, 2100 Pa, 3700 Pa, 8900 Pa and 23900 Pa at 130.2°C, 138°C, 150.56°C, 172.5°C and 202.49°C respectively were reported for the substance. Similarly, a limit vapour pressure of <200 Pa at 20°C was also reported for the substance.

In contact with water, the registered substance hydrolyses rapidly forming 3-(trihydroxysilyl)propyl methacrylate and methanol. The vapour pressure of the silanol hydrolysis product was estimated to be 1.2E-05 Pa at 25°C using a validated QSAR estimation method.

Methanol has a reported vapour pressure of 12790 Pa at 20°C (OECD 2004a).

Reference:

OECD (2004a): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1.