1,3,5-tris[[4-tert-butyl-3-hydroxy-2,6-xylyl]methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May - September 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was not conducted following to GLP or following the OECD guideline. However, it was well conducted via accepted methodology.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

yes

Remarks:

The OECD Guideline calls for a plate instead of a pan, which was used in this study.

GLP compliance:

no

Other quality assurance:

other: ISO 9001

Type of method:

effusion method: isothermal thermogravimetry

Temp.:

20 °C

Vapour pressure:

0 Pa

Temp.:

25 °C

Vapour pressure:

0 Pa

The estimated vapor pressure of the test substance at 20°C is: 0.000094226 Pa.

The estimated vapor pressure of the test substance at 25°C is: 0.000163485 Pa.

The vapor pressure equation in Pascal is: Y = -4183.2X + 10.244 - R² = 0.9986

where Y = log Pressure (Pa), and X = 1/K.

The equation was derived from the experimental evaporation rates of the test substance and standard reference material and the literature value of the standard reference material. The literature value vapor pressures of benzoic acid was plotted as log P vs. 1/K. This is in order to obtain the linear fit equation (Clausius-Clapeyron) to interpolate the vapor pressure at any temperature.

Benzoic acid was placed into 6 mm Al pans. The benzoic acid was added to the pan as a melt in order to obtain an even surface area throughout the pan and then allowed to resolidify. Afterwhich, several isothermic runs were made on the TGA. A plot of the evaporation rate of benzoic acid vs. vapor pressure is used to calibrate the instrument parameters.

Benzoic Acid Evaporation Rate Vs. Literature Value for Vapor Pressure

°C	1/K	Evaporation rate Benzoic Acid (wt%./min)	log evaporation rate (wt%./min)	Vapor pressure Pa	Log P PA
50	0.003095	0.00274	-2.562249437	1.8759531	0.273221977
60	0.003002	0.006225	-2.205860644	5.133205	0.710388609
70	0.002914	0.01665	-1.778585762	13.253002	1.122314264
80	0.002832	0.03513	-1.45432185	32.39919	1.510534153
90	0.002754	0.0707	-1.150580586	75.438114	1.877590822
100	0.00268	0.1609	-0.793443956	167.86247	2.224953609
130	0.00248	1.267	0.102776615	1236.715748	3.092269891
140	0.00242	2.004	0.301897717	2040.34899	3.309704457
160	0.002309	4.34	0.63748973	5181.457127	3.714451909

The equation generated from these data is used to calibrate the instrument. The log evaporation rates of the test substance was plugged into the equation Y = 1.0558X + 3.0261 in order to calculate the vapor pressure at the experimental temperature. Y = log pressure of benzoic acid (Pascal) and X = log evaporation rate of benzoic acid (wt.%/min). 

 

 Experimental Evaporation Rates on the Test Substance and Calculated Vapor

Sample Temperature		Evaporation Rate		Calculated Vapor Pressure
°C	1/K	Wt%/min	Log Wt%/min	Log P (Pa)	P (Pa)
80	0.002832	0.0000403	-4.3949	-1.6140	0.0243
90	0.002754	0.0000828	-4.0821	-1.2838	0.0520
100	0.002680	0.0001832	-3.7371	-0.9195	0.1204
120	0.002544	0.0005362	-3.2707	-0.4271	0.3740
150	0.002363	0.0030060	-2.5220	0.3634	2.3087

Calculated Vapor Pressure of Test Substance based on Calibration Curve and Evaporation Ratesplotted against Temperature

 

The method was validated by measuring the evaporation rates of substances of known vapor pressures. The vapor pressure was then calculated using the benzoic acid calibration curve. The differences in the experimental vapor pressure and the literature value are provided below followed by the plotted data. The literature values were calculated from the Antoine Equation provided in the Yaw’s handbook.

 

Antoine Equation: log P = A-B / (T+C)

 

Title: Yaws' Handbook of Antoine Coefficients for Vapor Pressure (2nd Electronic Edition) Table: Antoine Equation and Coefficients for Organic Compounds

material or substance name	CAS Registry No.	molecular formula	A	B	C	Tmin (°C)	Tmax (°C)
1-chlorooctane	111-85-3	C8H17Cl	7.1309	1638.28	201.999	-25	369.261
benzoic acid	65-85-0	C7H6O2	7.41844	1824.74	152.886	122.37	477.85
1-octanol	111-87-5	C8H18O	7.16033	1536.79	163.905	-15.5	379.35

Vapor pressure calculated is in mmHg

Experimental Vapor Pressures Vs. known values

Material	Temperature (°C)	log evaporation rate (wt%/min)	Log Vapor Pressure (mmHg)Experimental	Vapor Pressure (mmHg)Experimental	Vapor PressueLiterature Value	% Difference
Napthalene	60	-0.674074	0.125931	1.5471	1.3364	-15.77
Napthalene	80	-0.168578	0.637610	5.2871	4.3412	-21.79
Napthalene	100	0.213783	1.094439	13.3941	12.4291	-7.76
octanol	50	-0.898253	-0.024121	0.8971	0.9460	5.17
octanol	60	-0.661942	0.296749	1.5934	1.9804	19.54
octanol	90	0.176959	1.107712	12.2471	12.8148	4.43
1-chlorooctane	60	0.031004	0.879227	8.5888	7.5723	-13.42
1-chlorooctane	70	0.226084	1.105634	13.8007	12.7536	-8.21
1-chlorooctane	50	-0.160522	0.638807	5.3916	4.3532	-23.86
1-chlorooctane	80	0.387746	1.319220	20.4448	20.8555	1.97

Conclusions:

The vapor pressure of the test substance was determined by using an effusion method incorporating isothermal thermogravimetric analysis (TGA). The estimated vapor pressure of the test substance at 20°C and 25°C is 0.000094226 Pa and 0.000163485 Pa respectively. The linear fit equation is Y = -4183.2X + 10.244 where Y = log Pressure (Pa), and X = 1/K. The equation can be used to calculate the vapor pressure of the test substance at any temperature provided a phase change or decomposition does not occur.

Description of key information

The vapour pressure was determined by a method essentially equivalent to OECD guideline 104 and method ST-AN-25

Key value for chemical safety assessment

Vapour pressure:

0 Pa

at the temperature of:

20 °C

Additional information

The vapor pressure of the test substance was determined by using an effusion method incorporating isothermal thermogravimetric analysis (TGA). The estimated vapor pressure of the test substance at 20°C and 25°C is 0.000094226 Pa and 0.000163485 Pa respectively. The linear fit equation is Y = -4183.2X + 10.244 where Y = log Pressure (Pa), and X = 1/K. The equation can be used to calculate the vapor pressure of the test substance at any temperature provided a phase change or decomposition does not occur.