Benzene, 1-chloro-2,3-dimethyl-

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2003-04-11 to 2004-05-31

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Only 4 instead of >= 5 measured values (OECD 104); equilibrium points were not repeated at decreasing pressures as demanded by OECD 104

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Version / remarks:

1995

Qualifier:

according to guideline

Guideline:

other: ASTM E 1719-97

Deviations:

no

Principles of method if other than guideline:

The ASTM E 1719-97 (ASTM) ebulliometry method is similar to the dynamic method in OECD Guideline 104 (1995).

GLP compliance:

yes

Type of method:

dynamic method

Key result

Test no.:

#1

Temp.:

20 °C

Vapour pressure:

41 Pa

Remarks on result:

other: calculated based on Antoine equation

Transition / decomposition:

no

Using the Antoine equation constants calculated from the ASTM E 1719-97 (ASTM) boiling point data for n-decane (Table 1), pressures were calculated for each observed n-decane boiling point

as listed under "Calculated Pressure" in Table 2. The differences (observed - calculated pressures [kPa]) were determined as listed under "Obs'd-Calc'd Pressure" in Table 2 and plotted

against the observed pressure (abscissa, [kPa]). A regression curve was fitted to the data, resulting in the following equation:

y = ax^2 + bx +c,

a= -0.0009,

b= 0.1557,

c= -2.9498

R^2 = 0.9989

Table 1: Reported (ASTM E 1719-97) n-decane BP results

Observed Pressure				Boiling point (BP)
kPa	Log (kPa)	°C	°K	1/°K
1.00	0.0000	51.9	325.0	3.0769E-03
10.00	1.0000	101.9	375.0	2.6667E-03
30.00	1.4771	131.9	405.0	2.4691E-03
70.00	1.8451	160.9	434.0	2.3041E-03
101.30	2.0056	174.9	448.0	2.2321E-03
Antoine equation parameters
A	7.4620E+00
B	2.6581E+03
C	3.9161E+01

Table 2: n-Decane BP results

Observed Pressure				BP		Calculated Pressure*		Obs'd‑ Calc'd Pressure
mm Hg	kPa	Log	°C	°K	1/°K	Log (kPa)	kPa	kPa
		(kPa)
82.3	10.97	1.0404	105.0	378.2	2.6445E-03	1.0923	12.37	-1.39
258.3	34.44	1.5371	135.0	408.1	2.4502E-03	1.5192	33.08	1.39
548.3	73.10	1.8639	160.8	434.0	2.3044E-03	1.8436	70.14	3.35
767.3	102.30	2.0099	174.0	447.2	2.2364E-03	1.9961	99.10	3.20

*) using Antoine equation constants from Table 2

Using the relationship of the regression function, the observed pressures for 1-chloro-2,3-dimethylbenzene in Table 3 were adjusted to give the Adjusted Pressures. Antoine equation parameters (Table 3) were calculated based on these adjusted pressures and the corresponding boiling points. The absolute differences between the Adjusted and Calculated Pressures ranged from 0.17 to 1.07 kPa (see 'Deviation' in Table 3), and the absolute relative differences ranged from 0 to 7 % (see 'RD' in Table 3). The 1-chloro-2,3-dimethylbenzene vapour pressure at 20°C was calculated using the Antoine equation (parameters in Table 3), resulting in 41 Pa at 20°C (293 °K).

Tabelle 3: Results for 1-chloro-2,3-dimethylbenzene

Observed Pressure		Adjusted pressure		Boiling point			Calculated pressure		Deviation	Relative deviation [%]
mm Hg	kPa	mm Hg	kPa	°C	°K	1/°K	log (kPa)	kPa	kPa	Deviation / adjusted pressure
82	10.97	12.32	1.0907	119.1	392.3	2.5494E-03	1.059777	11.47564	0.85	7%
258	34.44	33.09	1.5198	150.9	424.1	2.3581E-03	1.529518	33.84681	-0.75	-2%
548	73.1	69.48	1.8419	176.8	450	2.2225E-03	1.848515	70.55291	-1.07	-2%
767	102.3	98.74	1.9945	190	463.2	2.1591E-03	1.993753	98.57183	0.17	0%

Antoine parameters

A	5.8473E+00
B	1.4005E+03
C	-9.9722E+01

Conclusions:

Vapour pressure (OECD 104): 41 Pa at 20°C

Executive summary:

The vapour pressure of 1-chloro-2,3-dimethylbenzene was determined according to the dynamic method (ebulliometry according to ASTM E 1719-97; similar to OECD 104) compliant with GLP.

Pressure-boiling point data pairs for n-decane given in ASTM E 1719-97 were used to calculate Antoine constants. Boiling points (BPs) at four different pressures (10.97, 34.44, 73.10, and 102.30 kPa) were determined for reference substance n-decane, and concurrently pressures for theses boiling points were calculated using the afore calcualted Antoine constants. Experimental pressure values for n-decane (abscissa) were plottet versus (observed - calculated pressue based on Antoine equation; ordinate) and fitted via polynomial regression. Then, pressure-boiling point pairs were measured for 1-chloro-2,3-dimethylbenzene (at 10.97, 34.44, 73.1, and 102.3 kPa - BP temperature range: 119.1 to 190 °C) and using the regression equation obtained before from n-decane, adjusted pressure was calculated from observed pressues. Then, Antoine constants were calculated from adjusted pressures and based on the Antoine equation, vapour pressure at 20°C was calculated.

Result: Vapour pressure for 1-chloro-2,3-dimethylbenzene at 20°C: 41 Pa.

Description of key information

Vapour pressure (OECD 104): 64.9 Pa at 20°C

Key value for chemical safety assessment

Vapour pressure:

64.9 Pa

at the temperature of:

20 °C

Additional information

The vapour pressure curve of the submission substance was determined in a Dynamic method experiment with an ebulliometer (although not explicitely mentioned experiment followed the guideline OECD 104). The Antoine constants were determined. The vapour pressure at 20°C is calculated at 64.9 Pa (Siemens 2002).

In a further supporting study the vapour pressure of 1-chloro-2,3-dimethylbenzene was determined according to the dynamic method (ebulliometry according to ASTM E 1719-97; similar to OECD 104) compliant with GLP. Pressure-boiling point data pairs for n-decane given in ASTM E 1719-97 were used to calculate Antoine constants. Boiling points (BPs). The vapour pressure for 1-chloro-2,3-dimethylbenzene at 20°C was calculated at: 41 Pa.

The more conservative (higher) value for the vapour pressure is used for risk characterisation.