Reaction mass of m,alpha-dimethylstyrene and p,alpha-dimethylstyrene

Vapour pressure

Administrative data

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 28, 2010 to November 30, 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Deviations:

no

GLP compliance:

no

Type of method:

effusion method: isothermal thermogravimetry

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of m,alpha-dimethylstyrene and p,alpha-dimethylstyrene

EC Number:

909-129-5

Molecular formula:

C10H12

IUPAC Name:

Reaction mass of m,alpha-dimethylstyrene and p,alpha-dimethylstyrene

Details on test material:

Manufacturer: Mitsui Chemicals, Inc.
Storage conditions: refrigeration (≤ 10°C)

Specific details on test material used for the study:

Chemical name: isopropenyltoluene
Abbreviated name: IPT
Lot No.: none (in-process product)
Purity: 98.82% (m-isomer, 74.25%; p-isomer, 24.57 %)
Manufacturer: Mitsui Chemicals, Inc.

Results and discussion

Vapour pressure

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

79.2 Pa

Transition / decomposition

Remarks on result:

other: No information on transition/decomposition was provided in the report

Any other information on results incl. tables

The results of individual measurements are shown in Table l.

Table 1: Evaporation rate

Measurement	Temperature (°C)	Initial weight (mg)	Weight (mg) after 60 min	Evaporation rate Vt1 (mg h^-1)
Measurement 1	25	45.51	43.50	2.01
Measurement 2	25	47.74	45.67	2.07
Measurement 3	25	45.89	43.66	2.23

The evaporation rate at 25°C, Vtl (mg*h-1) was converted to the molar evaporation rate per cm² at 25°C using the following equation:

Vt2 (mol cm-2  h-1= Vtl/1000/0.196*/molecular weight

* Upper surface area of the cell: 0.196 cm²

The following relationship is known between vapour pressure and molar evaporation rate per cm² at t°C:

Log Pt = At + (Bt x log Vt2), where At and Bt are temperature-specific constants at the carrier gas flow rate set for the apparatus used. The constants at 25°C are shown in Table 2.

Table 2: Constant for the calculation of vapour pressure

	Constant	Constant
Temperature (°C)	At	Bt
25	4.8926	1.2514

 

Results obtained in triplicate are 0.561 torr, 0.582 torr, 0.639 torr. The vapour pressure P25°C (torr) obtained was converted to the vapour pressure P25°C (Pa) using the following Equation:

P25°C (Pa) = P25°C (torr) x 133.3

The calculated vapour pressure P25°C (Pa) in each measurement is shown in Table 3.

Table 3: Vapour pressure of IPT

Measurement	Temperature (°C)	Vapour pressure (Pa)	Mean vapour pressure (Pa)	CV (%)
Measurement 1	25	74.8	79.2	6.8
Measurement 2	25	77.6
Measurement 3	25	85.2

 

The coefficient of variation (CV%) for values obtained in triplicate was 6.8%. According to Table 1 in the OECD test guideline 104, the estimated reproducibility of "the effusion method: isothermal thermogravimetry" is up to 50%. The reproducibility found was considered to be within the acceptable range because the coefficient of variation at 25°C was less than 50%.

Applicant's summary and conclusion

Conclusions:

Vapour pressure of isopropenyltoluene: 79.2 Pa (25°C)

Executive summary:

The vapour pressure of isopropenyltoluene (98.82% pure) was determined according to OECD 104 using the Effusion method: isothermal thermogravimetry at 25°C in triplicate using a thermogravimetric analyzer TGA-50 (Shimadzu Corporation). A sample was introduced into a platinum cell, the cell was then introduced into the thermogravimetric analyzer. The temperature was set at 25°C, and monitoring of the sample weight was started after confirming that steady state had been established. Sample weight was read at the beginning of the monitoring and 60 min later, and the evaporation rate Vt1 (mg*h-1) was determined. The triplicate measurements gave values for vapour pressure at 25°C of 74.8, 77.6 and 85.2 Pa, mean 79.2 Pa with CV 6.8%. It is concluded that the vapour pressure of isopropenyltoluene (98.82% pure) at 25°C is 79.2 Pa.