Spiro[piperidine-1,1'-pyrrolidinium] bifluoride

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:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Deviations:

no

GLP compliance:

no

Type of method:

effusion method: Knudsen cell

Test no.:

#1

Temp.:

23.3 °C

Vapour pressure:

0.015 Pa

Test no.:

#2

Temp.:

49.8 °C

Vapour pressure:

0.031 Pa

Vapour pressure:

0.031 Pa

Remarks on result:

other: calculated from the Clausius-Clapeyron equation

The vapor pressures obtained at temperatures of approximately 23 °C and 50 °C are summarized below:

T [°C]	p [Pa]
23.3	0.0154
49.8	0.0311

In a limited temperature range, up to an interval of around 120 K, the logarithm of the vapor pressure of a pure substance can be considered to be a linear function of the inverse of the thermodynamic temperature according to the simplified Clausius-Clapeyron equation.

The Clausius-Clapeyron equation was fitted to the data of RFR 6634 in order to extrapolate the vapor pressure to the relevant temperatures of 20 °C, 25 °C, 50 °C and 55 °C:

T [°C]	T [K]	p [mbar]	p [Pa]
20	293.15	0.00014	0.014
25	298.15	0.000162	0.01619
50	323.15	0.000313	0.03128
55	328.15	0.000353	0.03526

1. Based on the results, the vapor pressure of the compound is calculated as being equal to 0,014 Pa at 20 °C, 0,01619 Pa at 25 °C, 0,03128 Pa at 50 °C and 0,03526 Pa at 55 °C.

2. The vapor pressure of the compound can be calculated for additional temperatures, between approx. 0 °C to 80 °C, through the following equation: ln(p) = -21110.9/(R*T) + 4.392.

3. The application of the equation for temperatures outside the given temperature range will undoubtedly produce values affected by an error in excess.

Conclusions:

The vapor pressure of RFR 6634 was measured at the temperatures of 23 °C and 50 °C using the Knudsen effusion method (mass-loss technique), according to the guidelines OECD 104 / EU A.4. Based on the results determined at 23.3 °C (0.0154 Pa) and 49.8 °C (0.0311 Pa), the vapor pressure of the compound is calculated by applying simplified Clausius-Clapeyron equation as being equal to 0,014 Pa at 20 °C, 0,01619 Pa at 25 °C, 0,03128 Pa at 50 °C and 0,03526 Pa at 55 °C.

Executive summary:

The vapor pressure of RFR 6634 was measured at the temperatures of 23 °C and 50 °C using the Knudsen effusion method (mass-loss technique), according to the guidelines OECD 104 / EU A.4. The quality of the apparatus was previously verified with the measurement of well-known reference compounds.

The Knudsen effusion apparatus used in this work was recently developed, representing the state-of-the-art. Its quality is regularly tested through the study of reference substances. For the experiments, the effusion cells are loaded with approx. 400 mg of compound to be studied. The mass loss in each experiment is determined by careful weighing, in an analytical balance with a resolution of 0.01 mg.

Whenever possible, the experiments are planned so that the amount of effused substance does not vary significantly from one experiment to the next. This is done using shorter effusion times for the experiments at higher temperatures, and longer times for the lower temperatures. In any case, effusion times are always longer than 1 x 104 s in order to minimize the relative uncertainty of the effusion time. A more detailed description of the apparatus and of the experimental procedure can be found in the literature (Fonseca et al.).

The quality of the apparatus was verified through the thorough study of reference compounds and the comparison of the obtained results with the values existing in literature, at temperatures ranging from -4 °C to 140 °C and pressures varying from 0.001 Pa to 1 Pa. Phenanthrene, anthracene, benzoic acid and benzanthrone were used as reference compounds. For all these substances, the agreement between the measured vapor pressures and the literature data is remarkable, confirming the superior quality of the apparatus used. Some of the results obtained with reference compounds down to 1 mPa using this apparatus can also been found in the scientific literature.

For both experiments (temperatures) three effusion cells were used simultaneously, in order to minimize measurement errors through averaging.

The vapor pressures obtained at temperatures of approximately 23 °C and 50 °C are summarized below:

T [°C]	p [Pa]
23.3	0.0154
49.8	0.0311

In a limited temperature range, up to an interval of around 120 K, the logarithm of the vapor pressure of a pure substance can be considered to be a linear function of the inverse of the thermodynamic temperature according to the simplified Clausius-Clapeyron equation.

The Clausius-Clapeyron equation was fitted to the data of RFR 6634 in order to extrapolate the vapor pressure to the relevant temperatures of 20 °C, 25 °C, 50 °C and 55 °C:

T [°C]	T [K]	p [mbar]	p [Pa]
20	293.15	0.00014	0.014
25	298.15	0.000162	0.01619
50	323.15	0.000313	0.03128
55	328.15	0.000353	0.03526

Conclusion

1. Based on the results, the vapor pressure of the compound is calculated as being equal to 0,014 Pa at 20 °C, 0,01619 Pa at 25 °C, 0,03128 Pa at 50 °C and 0,03526 Pa at 55 °C.

2. The vapor pressure of the compound can be calculated for additional temperatures, between approx. 0 °C to 80 °C, through the following equation: ln(p) = -21110.9/(R*T) + 4.392.

3. The application of the equation for temperatures outside the given temperature range will undoubtedly produce values affected by an error in excess.

Description of key information

The vapor pressure of RFR 6634 was measured at the temperatures of 23 °C and 50 °C using the Knudsen effusion method (mass-loss technique), according to the guidelines OECD 104 / EU A.4. The quality of the apparatus was previously verified with the measurement of well-known reference compounds.

The Knudsen effusion apparatus used in this work was recently developed, representing the state-of-the-art. Its quality is regularly tested through the study of reference substances. For the experiments, the effusion cells are loaded with approx. 400 mg of compound to be studied. The mass loss in each experiment is determined by careful weighing, in an analytical balance with a resolution of 0.01 mg.

Whenever possible, the experiments are planned so that the amount of effused substance does not vary significantly from one experiment to the next. This is done using shorter effusion times for the experiments at higher temperatures, and longer times for the lower temperatures. In any case, effusion times are always longer than 1 x 104 s in order to minimize the relative uncertainty of the effusion time. A more detailed description of the apparatus and of the experimental procedure can be found in the literature (Fonseca et al.).

The quality of the apparatus was verified through the thorough study of reference compounds and the comparison of the obtained results with the values existing in literature, at temperatures ranging from -4 °C to 140 °C and pressures varying from 0.001 Pa to 1 Pa. Phenanthrene, anthracene, benzoic acid and benzanthrone were used as reference compounds. For all these substances, the agreement between the measured vapor pressures and the literature data is remarkable, confirming the superior quality of the apparatus used. Some of the results obtained with reference compounds down to 1 mPa using this apparatus can also been found in the scientific literature.

For both experiments (temperatures) three effusion cells were used simultaneously, in order to minimize measurement errors through averaging.

The vapor pressures obtained at temperatures of approximately 23 °C and 50 °C are summarized below:

T [°C]	p [Pa]
23.3	0.0154
49.8	0.0311

In a limited temperature range, up to an interval of around 120 K, the logarithm of the vapor pressure of a pure substance can be considered to be a linear function of the inverse of the thermodynamic temperature according to the simplified Clausius-Clapeyron equation.

The Clausius-Clapeyron equation was fitted to the data of RFR 6634 in order to extrapolate the vapor pressure to the relevant temperatures of 20 °C, 25 °C, 50 °C and 55 °C:

T [°C]	T [K]	p [mbar]	p [Pa]
20	293.15	0.00014	0.014
25	298.15	0.000162	0.01619
50	323.15	0.000313	0.03128
55	328.15	0.000353	0.03526

Conclusion

1. Based on the results, the vapor pressure of the compound is calculated as being equal to 0,014 Pa at 20 °C, 0,01619 Pa at 25 °C, 0,03128 Pa at 50 °C and 0,03526 Pa at 55 °C.

2. The vapor pressure of the compound can be calculated for additional temperatures, between approx. 0 °C to 80 °C, through the following equation: ln(p) = -21110.9/(R*T) + 4.392.

3. The application of the equation for temperatures outside the given temperature range will undoubtedly produce values affected by an error in excess.

Key value for chemical safety assessment

Vapour pressure:

0.031 Pa

at the temperature of:

23.3 °C