3,5,5-trimethylhexanoic acid

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 1984

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientifically acceptable, well documented study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Version / remarks:

1981

GLP compliance:

no

Type of method:

dynamic method

Key result

Temp.:

20 °C

Vapour pressure:

0.005 hPa

Remarks on result:

other: extrapolated from the determined regression equation

The regression of the results leads with a mean relative deviation of 0.34% to the following equotation:

ln p (bar) = 11.8753 - 4951.47/(184.92+T[°C])

The vapour pressure at 20°C was calculated from the regression equation.

Calculated boiling temperature (from regression equation) at 1013 hPa is 232.5 °C. This matches closely with the boiling temperature determined in the valid key study (photocell detection) of 236 °C.

Experimental data and calculated values from regression:

Temperature	Vapour pressure	Vapour pressure	Vapour pressure	Absolute relative
T [°C]	measured [mbar]	Regression [mbar]	Regression [Pa]	deviation
20	--	0.00	0.46	--
25	--	0.01	0.82	--
35	--	0.02	2.39	--
54.48	0.15	0.15	14.96	2.65E-03
57.78	0.2	0.20	19.82	9.07E-03
62.85	0.3	0.30	30.09	2.89E-03
69.33	0.5	0.50	50.07	1.40E-03
73.89	0.7	0.71	70.57	8.08E-03
78.78	1	1.01	100.62	6.17E-03
88.79	2	2.00	199.94	2.97E-04
95.02	3	2.99	299.05	3.16E-03
103.34	5	4.98	498.26	3.47E-03
109.12	7	6.98	698.39	2.30E-03
115.49	10	9.98	998.10	1.90E-03
128.69	20	19.97	1997.40	1.30E-03
136.96	30	29.97	2996.67	1.11E-03
148.11	50	50.15	5015.49	3.10E-03
	mean relative deviation in %:			0.34%

Conclusions:

Vapour pressure (OECD 104): 0.46 Pa (20°C)

Executive summary:

The vapour pressure of the submission substance was determined equivalent to OECD 104 applying the dynamic method.

Based on 14 measured values between 54.5 °C and 148.1 °C the following regression equation was obtained (mean relative deviation: 0.34%):

ln p (bar) = 11.8753 - 4951.47/(184.92+T[°C])

The vapour pressure at 20°C was calculated from this regression equation:

Vapour pressure (OECD 104): 0.46 Pa (20°C).

The calculated boiling temperature (from regression equation) at 1013 hPa is 232.5 °C. This matches closely with the boiling temperature determined in the valid key study (photocell detection) of 236 °C.

Description of key information

0.0046 hPa at 20 °C

Key value for chemical safety assessment

Vapour pressure:

0.005 hPa

at the temperature of:

20 °C

Additional information

The vapour pressure of the submission substance was determined equivalent to OECD 104 applying the dynamic method (BASF 1984).

Based on 14 measured values between 54.5 °C and 148.1 °C the following regression equation was obtained (mean relative deviation: 0.34%):

ln p (bar) = 11.8753 - 4951.47/(184.92+T[°C])

The vapour pressure at 20°C was calculated from this regression equation:

Vapour pressure (OECD 104): 0.46 Pa (20°C).

The calculated boiling temperature (from regression equation) at 1013 hPa is 232.5 °C. This matches closely with the boiling temperature determined in the valid key study (photocell detection) of 236 °C.

Data supporting the results of the valid key study are available (BASF 2012), giving very similar results:

The vapour pressure of the submission substance was determined equivalent to OECD 104 applying the dynamic method.

Based on 17 measured values between the tempearature range of 73.4 to 231.5 °C the following regression equation was obtained (mean relative deviation: 0.50%):

ln(p/Pa) = 243.35865 - 17024.3923 / T[K] - 34.25424*lnT[K] + 0.02988*T[K]

The vapour pressure at 20°C was calculated from this regression equation:

Vapour pressure (OECD 104): 0.0058 hPa (20°C).