Pyrocatechol

Vapour pressure

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

vapour pressure

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

This study is not an experimental one. Instead, calculation was used to extrapolate vapour pressure at 20 and 25°C. The data obtained appears consistent with the handbooks values measured at higher temperatures.

Qualifier:

no guideline available

Principles of method if other than guideline:

Vapour pressures at 20 and 25°C were estimated by calculation.

GLP compliance:

not specified

Temp.:

25 °C

Vapour pressure:

ca. 0.005 kPa

From the equation above mentionned, Vp = 0.003 kPa at 20°C (value adopted by HSDB), and  0.005 kPa at 25°C.

However, since Pyrocatechol has a melting point of 105°C (<118.5-245.5°C used for the generation of the equation), the extrapolated VP refers to a 

 "super-cooled" liquid, and not the solid. The "super-cooled" value can be further extrapolated to the solid-phase VP using various methods which  

will lower the super-cooled value by a factor of 6 to 11 (Bill Meylan,  personal communication).

Conclusions:

Catechol presents an extrapolated vapour pressure value of 0.005 hPa at 25°C.

Executive summary:

In this study, the authors developped a equation to extrapolate the vapour pressure at 25°C from values measured at temperatures ranging from 118.5 to 245.5°C. By doing so, they reported a vapour pressure of 0.005 kPa at 25°C for catechol.

Reference 2

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Data comes from peer-reviewed handbooks cited among "reference books containing peer-reviewed physico-chemical data" in the ECHA guidance document on information requirements and chemical safety assessment (R.7a).

Reason / purpose for cross-reference:

reference to same study

Guideline:

other: See below

Principles of method if other than guideline:

Measured data but no information on the method.

GLP compliance:

not specified

Type of method:

other: no data available

Temp.:

104 °C

Vapour pressure:

6.66 hPa

Temp.:

118.3 °C

Vapour pressure:

13.3 hPa

Temp.:

150.6 °C

Vapour pressure:

53.3 hPa

Temp.:

176 °C

Vapour pressure:

133 hPa

Temp.:

197.7 °C

Vapour pressure:

266 hPa

Temp.:

221.5 °C

Vapour pressure:

533 hPa

Conclusions:

Catechol presents a vapour pressure ranging from 6.66 to 533 hPa in the temperature range from 104 to 221.5°C.

Executive summary:

Several peer-reviewed handbooks report vapour pressure ranging from 6.66 to 533 hPa in the temperature range from 104 to 221.5°C for catechol.

Description of key information

Range of vapour pressure:
0.05 hPa at 25°C;
6.66 hPa at 104°C;
13.3 hPa at 118.3°C;
53.3 hPa at 150.6°C;
133 hPa at 176°C;
266 hPa at 197.7°C;
533 hPa at 221.5°C

Key value for chemical safety assessment

Vapour pressure:

0.05 hPa

at the temperature of:

25 °C

Additional information

Several peer-reviewed handbooks and a publication give consistent values in a range of temperatures between 25 and 221.5°C.