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Vapour pressure

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Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Valid method for temperature/pressure range, substance purity given, very good number of data points, and raw data tabulated with deviations from fitted curve. However, limited experimental details, no equipment calibration details, and no measurements in 0-50°C range.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
yes
Remarks:
no measurement in 0-50°C range
GLP compliance:
no
Type of method:
dynamic method
Remarks:
comparative ebulliometry
Temp.:
25 °C
Vapour pressure:
86.86 Pa
Remarks on result:
other: Calculated from Wagner equation
Temp.:
35 °C
Vapour pressure:
200.3 Pa
Remarks on result:
other: Calculated from Wagner equation
Temp.:
45 °C
Vapour pressure:
429.3 Pa
Remarks on result:
other: Calculated from Wagner equation

Tabulated pressure data in temperature range: 350.801K to 456.537K, n=26.

The Antoine equation was only used over a restricted temperature range (398.237K -456.537K) to achieve a good fit: LnP=A+B/(T+C), where P in kPa and T in K. Constants: A=13.56446, B=-2689.899, C=-133.310.

The Wagner equation was used for the full temperature range: ln(P/Pc)=(n1*t+n2*t^1.5 +n3*t^2.5 +n4*t^5)/Tr where Tr=T/Tc and t=(1 -Tr) and the constants Tc=650.0K, lnPc=8.35698, n1=-7.12838, n2=1.40189, n3=-5.60756, n4=-9.57158.

4 samples were used over the temperature range, with the last sample being used for the last 3 measurements only.

Conclusions:
The liquid phase vapour pressure of cyclohexanol was determined experimentally and could be extrapolated from the Wagner equation to be 86.86 Pa at 25 °C.
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Valid method for temperature/pressure range, substance purity given, good number of data points, raw data tabulated, accuracy of temperature and pressure reading given, and good experimental details. However, no equipment calibration details, and no measurements in 0-50°C range.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
yes
Remarks:
no measurement in 0-50°C range
Principles of method if other than guideline:
Apparatus described by Walas, S.M., Phase Equilibria in Chemical Engineering, Butterworth, London, 1985.
GLP compliance:
no
Type of method:
dynamic method
Remarks:
glass recirculation still
Temp.:
25 °C
Vapour pressure:
75.74 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
35 °C
Vapour pressure:
184.4 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
45 °C
Vapour pressure:
409.9 Pa
Remarks on result:
other: Calculated from Antoine equation

Tabulated pressure data in temperature range: 343.45K to 433.55K, n=15.

Curve fitted to LnP=A-B/(T+C), where P in kPa and T in K. Constants: A=13.94898, B=2905.618, C=-122.3649 with mean absolute deviation between experimental and calculated P = 0.070kPa.

Conclusions:
The liquid phase vapour pressure of cyclohexanol was determined experimentally and could be extrapolated from the Antoine equation to be 75.74 Pa at 25 °C.
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Valid method for temperature/pressure range, substance purity given, good number of data points, raw data tabulated with deviations from fitted curve, accuracy of temperature and pressure reading given, good experimental details. However, no measurements in the data range 0-50°C.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
yes
Remarks:
No measurement in 0-50°C range
Principles of method if other than guideline:
Method and equipment ask described by Rogalski, M., et al, Fluid Phase Equilibria, 1980, 5, 97-112
GLP compliance:
no
Type of method:
dynamic method
Remarks:
Swietoslawski ebulliometer
Temp.:
25 °C
Vapour pressure:
70.22 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
35 °C
Vapour pressure:
174.3 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
45 °C
Vapour pressure:
393.4 Pa
Remarks on result:
other: Calculated from Antoine equation

Tabulated pressure data in temperature range: 387.34K to 421.87K, n=11.

Curve fitted to LogP=A-B/(C+T), where P in mmHg and T in °C. Constants: A=6.882615(0.012734), B=1227.194(7.087), C=146.370(0.802), where values in brackets are calculated by error propagation.

Deviation of the fitted curve from the experimental points tabulated: maximum ΔP=0.5mbar, stdev=0.3293mbar

Conclusions:
The liquid phase vapour pressure of cyclohexanol was determined experimentally and could be extrapolated from the Antoine equation to be 70.22 Pa at 25 °C.
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Valid method for temperature/pressure range, substance impurities reported, required number of data points, raw data tabulated, accuracy of pressure reading given, adequate experimental details, measurements down to 45.5°C and 3 in range 0-50°C. However, no temperature calibration reported, some uncertainty surrounding temperature/pressure methods used below 30mmHg.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
Principles of method if other than guideline:
Flow still described by Dawe, R.A., et al, J. Chem. Eng. Data, 1973, 18, 44.
GLP compliance:
no
Type of method:
dynamic method
Remarks:
flow still
Temp.:
25 °C
Vapour pressure:
79.97 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
35 °C
Vapour pressure:
191.4 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
45 °C
Vapour pressure:
420 Pa
Remarks on result:
other: Calculated from Antoine equation

Tabulated pressure data in temperature range: 45.5°C to 160.1°C, n=16.

Curve fitted to LogP=A-B/(C+T), where P in mmHg and T in °C. Constants: A=7.0385, B=1318.5, C=156.60

Deviation of the calculated from the experimental boiling points: root mean square 0.18°C.

Conclusions:
The liquid phase vapour pressure of cyclohexanol was determined experimentally and could be extrapolated from the Antoine equation to be 79.97 Pa at 25 °C.
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Valid method for temperature/pressure range, good number of data points, raw data tabulated with deviations from fitted curve, accuracy of temperature and pressure reading given, adequate experimental details. However, high purity of substance implied but not determined, no measurement below 50°C, no equipment calibration details.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
yes
Remarks:
no measurements in 0-50°C range
Principles of method if other than guideline:
Cyclohexanol vapour pressures were reported as by-products of other research.
GLP compliance:
no
Type of method:
dynamic method
Remarks:
Swietoslawski-Ebulliometer
Temp.:
25 °C
Vapour pressure:
57.06 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
35 °C
Vapour pressure:
150.7 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
45 °C
Vapour pressure:
355.9 Pa
Remarks on result:
other: Calculated from Antoine equation

Tabulated pressure data in temperature range: 93.73°C to 160.70°C, n=16.

Curve fitted to LogP=A-B/(C+t), where P in mmHg and t in °C. Constants: A=6.5562, B=1067.8, C=129.2

Percentage deviation of the fitted curve from the experimental points tabulated: maximum deviation in P=-1.9%.

Conclusions:
The liquid phase vapour pressure of cyclohexanol was determined experimentally and could be extrapolated from the Antoine equation to be 57.06 Pa at 25 °C.
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Valid method for temperature/pressure range, substance purity given, required number of data points, raw data tabulated with deviations from calculated values, accuracy of temperature and pressure reading given, adequate experimental details (referenced), measurements down to 30°C (3 in range 0-50°C).
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
Principles of method if other than guideline:
Static apparatus similar to McGlashan, M.L., et al, Trans. Faraday Soc., 1961, 57, 588.
GLP compliance:
no
Type of method:
static method
Temp.:
25 °C
Vapour pressure:
105.7 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
35 °C
Vapour pressure:
233.1 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
45 °C
Vapour pressure:
480.9 Pa
Remarks on result:
other: Calculated from Antoine equation

Tabulated pressure data in temperature range: 303.147K to 373.278K, n=8.

Curve fitted to LogP=A-B/(T-C), where P in kPa and T in K. Constants: A=6.81617, B=1690.118, C=81.245

Deviation of the calculated from the experimental points tabulated: maximum ΔP=0.05kPa

Conclusions:
The liquid phase vapour pressure of cyclohexanol was determined experimentally and could be extrapolated from the Antoine equation to be 105.7 Pa at 25 °C.
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Valid method for temperature/pressure range, substance purity given, very good number of data points, raw data tabulated with deviations from fitted curve, very good experimental details (referenced), and equipment calibration details. Very carefull study, however, no measurements in range 0-50°C.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
yes
Remarks:
no measurement in 0-50°C range
Principles of method if other than guideline:
Details in Steele, W.V. et al, J. Chem. Eng. Data, 1997, 42(6), -1021.
GLP compliance:
no
Type of method:
dynamic method
Remarks:
comparative ebulliometer
Specific details on test material used for the study:
Purchased from Aldrich Chemical Co
Temp.:
25 °C
Vapour pressure:
90.74 Pa
Remarks on result:
other: Calculated from Wagner equation
Temp.:
35 °C
Vapour pressure:
206.4 Pa
Remarks on result:
other: Calculated from Wagner equation
Temp.:
45 °C
Vapour pressure:
438.1 Pa
Remarks on result:
other: Calculated from Wagner equation

Tabulated pressure data in temperature range: 341.241K to 470.984K, n=22.

Curve fitted to Wagner equation: ln(p/pc)=(1/Tr)[AY+BY^1.5 +CY^2.5 +DY^5] where Tr=T/Tc and Y=(1 -Tr), and constants are A=-7.67095, B=3.19308, C=-8.34213, D=-5.82888, Tc=648K, pc=4075Pa. Tc was determined by DSC.

Last two vapour pressures were not included in the fit due to observation of sample decomposition.

Conclusions:
The liquid phase vapour pressure of cyclohexanol was determined experimentally and could be extrapolated from the Wagner equation to be 90.74 Pa at 25 °C.
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Valid method for temperature/pressure range, substance purity given, required number of data points, raw data tabulated with deviations from fitted curve, accuracy of temperature and pressure reading given, adequate experimental details, measurements down to 50°C. However, no equipment calibration details, pressure gauge uncertainty relatively large at low pressures.
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
yes
Remarks:
Only one measurement in 0-50°C range
GLP compliance:
no
Type of method:
dynamic method
Remarks:
glass recirculation still
Temp.:
25 °C
Vapour pressure:
71 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
35 °C
Vapour pressure:
174.7 Pa
Remarks on result:
other: Calculated from Antoine equation
Temp.:
45 °C
Vapour pressure:
391.9 Pa
Remarks on result:
other: Calculated from Antoine equation

Tabulated pressure data in temperature range: 322.25K to 433.30K, n=9.

Curve fitted to LogP=A-B/(C+T), where P in bar and T in K. Constants: A=4.06566, B=1258.75, C=-123.673

Deviation of the fitted curve from the experimental points tabulated: maximum ΔP=0.5mbar, stdev=0.3293mbar

Conclusions:
The liquid phase vapour pressure of cyclohexanol was determined experimentally and could be extrapolated from the Antoine equation to be 71.0 Pa at 25 °C.

Description of key information

Mean vapour pressure of 11 independent studies extrapolated to 25 °C: 82.39 Pa

Key value for chemical safety assessment

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

Additional information

A large body of vapour pressure data exists in the literature for cyclohexanol, as a result only data from multipoint vapour pressure vs temperature studies was used (i.e. single point measurements were discarded), as it is considered to be inherently more reliable and closest to guideline approaches to vapour pressure measurement.

12 studies were found which fit these criteria, which ranged in quality from extremely precise measurements done to very high standard (e.g. Steele 1997), to poorer quality older studies. Glaser (1957) was discarded due to experimental deficiencies. However, very few reported data in the temperature range of interest (i.e. 0 -50 °C), which required extrapolation from higher temperature using the supplied curve fitting equations. This is partially explained by the presence of the melting point at ca. 25 °C, necessitating the use of higher temperatures for the method of choice, ebulliometry.

As a result, a statistical approach was taken whereby the mean was calculated from the extrapolated data: 82.39 Pa at 25 °C (n=11, stdev=15.18 Pa) and 95% C.I.=72.19 -92.59 °C (t-distribution). The result is considered to be relevant, reliable, and adequate for risk assessment, and classification purposes. The available data for this endpoint is conclusive.

Further endpoint study record (BASF, 1981) has been included as supporting information.