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Vapour pressure

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Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
No test substance information, no guideline, secondary literature, but reference handbook containing peer-reviewed physico-chemical data.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Vapor pressures were measured to a pressure limit of 270 kPa or lower decomposition point for all compounds using a twin ebulliometric system. Liquid-phase densities along the saturation line were measured for each compound over a range of temperature (ambient to a maximum of 548 K). A differential scanning calorimeter (DSC) was used to measure two-phase (liquid + vapor) heat capacities for each compound in the temperature region ambient to the critical temperature or lower decomposition point.
GLP compliance:
not specified
Type of method:
other: twin ebulliometric system
Vapour pressure:
>= 2 004 - <= 31 187 Pa
Remarks on result:
other: 165.4 - 243.1°C

A critical temperature of (775 +/- 5) K, a critical pressure of (3700 +/- 300) kPa, and a critical density of (297 +/- 15) kg‚m-3 were obtained from the fitting procedures used in this research for 4-tert-butylcatechol.

Conclusions:
The vapour pressure ranged from 2004 Pa at 165.4°C to 31187 Pa at 243.1°C
Executive summary:

In this study, the vapour pressure and other physico-chemicals properties (Heat Capacity, and Density along the Saturation Line) were measured for several Compounds including the 4-ter-butylpyrocatechol.

The vapour pressure of the 4-ter-butylpyrocatechol ranged from 2004 Pa at 165.4°C to 31187 Pa at 243.1°C.

Endpoint:
vapour pressure
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Calculation model ussually accepted for estimation of pKa
Justification for type of information:
1. SOFTWARE
MPBPVP

2. MODEL
EPISUITE

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Oc(c(O)cc(c1)C(C)(C)C)c1

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: yes; 1.4 vapour pressure
- Unambiguous algorithm: yes, see User Guide section 7.3
- Defined domain of applicability: no universally accepted definition of model domain. See User Guide section 7.3.3
- Appropriate measures of goodness-of-fit and robustness and predictivity: See User Guide section 7.3.2
- Mechanistic interpretation: not applicable

5. APPLICABILITY DOMAIN
- Descriptor domain:not available for this commercial QSAR
- Structural and mechanistic domains: not available for this commercial QSAR
- Similarity with analogues in the training set:not available for this commercial QSAR

6. ADEQUACY OF THE RESULT
The test item is included in the validity domain of MBBPVP program (see section "Any others information on results incl. tables' for more details). Therefore, this QSAR is considered relevante for the test item vapour pressure estimation.
Principles of method if other than guideline:
QSAR calculation
GLP compliance:
no
Temp.:
25 °C
Vapour pressure:
0.041 Pa
Remarks on result:
other: Mean between Antoine and Grain methods, as recommended in Mpbpwin user manual.
Temp.:
25 °C
Vapour pressure:
0.038 Pa
Remarks on result:
other: Calculation done with Antoin Method.
Temp.:
25 °C
Vapour pressure:
0.044 Pa
Remarks on result:
other: Calculation done with Grain method

It is considered that:

1- the molecular weight of 4-TBC is within the range of the training set compounds,

2- There are no functional groups or structures not represented in the training set.

Therefore it is considered that the MPBPW in methodology is accurate for predicting the vapour pressure of 4-TBC.

MPBPVP (v1.43) Program Results:

===============================

Experimental Database Structure Match:

Name     :  1,2-Benzenediol, 4-(1,1-dimethylethyl)-

CAS Num  :  000098-29-3

Exp MP (deg C):  54.3

Exp BP (deg C):  285

Exp VP (mm Hg):  ---

SMILES : Oc(c(O)cc(c1)C(C)(C)C)c1

CHEM   : 1,2-Benzenediol, 4-(1,1-dimethylethyl)-

MOL FOR: C10 H14 O2

MOL WT : 166.22

------------------------ SUMMARY MPBVP v1.43 --------------------

Boiling Point:  281.17 deg C (Adapted Stein and Brown Method)

Melting Point:  181.58 deg C (Adapted Joback Method)

Melting Point:   50.52 deg C (Gold and Ogle Method)

Mean Melt Pt :  116.05 deg C (Joback; Gold,Ogle Methods)

Selected MP:   83.28 deg C (Weighted Value)

Vapor Pressure Estimations (25 deg C):

 (Using BP: 285.00 deg C (exp database))

 (Using MP: 54.30 deg C (exp database))

  VP:  0.000284 mm Hg (Antoine Method)

     :  0.0378 Pa  (Antoine Method)

  VP:  0.000333 mm Hg (Modified Grain Method)

     :  0.0444 Pa  (Modified Grain Method)

  VP:  0.0041 mm Hg (Mackay Method)

     :  0.547 Pa  (Mackay Method)

 Selected VP:  0.000333 mm Hg (Modified Grain Method)

            :  0.0444 Pa (Modified Grain Method)

 Subcooled liquid VP:  0.000621 mm Hg (25 deg C, Mod-Grain method)

                    :  0.0828 Pa  (25 deg C, Mod-Grain method)

-------+-----+--------------------+----------+---------

TYPE  | NUM |  BOIL DESCRIPTION  |  COEFF   |  VALUE  

-------+-----+--------------------+----------+---------

Group |  3  |  -CH3              |   21.98  |   65.94

Group |  1  |  >C<               |    4.50  |    4.50

Group |  2  |  -OH (phenol)      |   70.48  |  140.96

Group |  3  |  CH (aromatic)     |   28.53  |   85.59

Group |  3  |  -C (aromatic)     |   30.76  |   92.28

  *   |     |  Equation Constant |          |  198.18

=============+====================+==========+=========

RESULT-uncorr|  BOILING POINT in deg Kelvin  |  587.45

RESULT- corr |  BOILING POINT in deg Kelvin  |  554.33

            |  BOILING POINT in deg C       |  281.17

-------------------------------------------------------

-------+-----+--------------------+----------+---------

TYPE  | NUM |  MELT DESCRIPTION  |  COEFF   |  VALUE  

-------+-----+--------------------+----------+---------

Group |  3  |  -CH3              |   -5.10  |  -15.30

Group |  1  |  >C<               |   46.43  |   46.43

Group |  2  |  -OH (phenol)      |   82.83  |  165.66

Group |  3  |  CH (aromatic)     |    8.13  |   24.39

Group |  3  |  -C (aromatic)     |   37.02  |  111.06

  *   |     |  Equation Constant |          |  122.50

=============+====================+==========+=========

  RESULT    |  MELTING POINT in deg Kelvin  |  454.74

            |  MELTING POINT in deg C       |  181.58

-------------------------------------------------------

Conclusions:
QSAR calculated VP = 0.0411 Pa at 25°C (mean between Antoine and Grain methods).
Executive summary:

The vapour pressure of 4-tert-butylpyrocatechol was estimated at 25°C with the recommended QSAR Mpbpwin (EPI Suite TM). The selected result calculated by the model is 0.0411 Pa.

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Chemical equilibria of reactions of transalkylation among tert-butylphenols and tert-butylcatechols in the liquid phase were investigated in the temperature range 373-483 K. The molar enthalpies of fusion of the catechol, 4-tert-butylcatechol, and 3,5-di-tert-butylcatechol were measured by DSC. The standard molar enthalpies of formation at the temperature T = 298.15 K were measured by means of combustion calorimetry for 4-tert-butylcatechol and 3,5-di-tert-butylcatechol. The standard molar enthalpies of sublimation of these compounds, and also the enthalpy of vaporization of 3-tert-butylcatechol, were obtained from the temperature dependence of the vapor pressure measured by the transpiration method.
GLP compliance:
not specified
Type of method:
other: Transpiration method
Specific details on test material used for the study:
All compounds were purchased from Aldrich or Acros Ltd.
Key result
Temp.:
30.35 °C
Vapour pressure:
0.103 Pa
Key result
Temp.:
50.15 °C
Vapour pressure:
1.095 Pa

The vapour pressure of the 4-ter-butylpyrocatechol ranged from 0.103 at 30.35°C to 1.095 Pa at 50.15°C.

The equation was Equation: ln(p/ Pa)=36.84-11873( T/K)-1

Conclusions:
The vapour pressure of the 4-ter-butylpyrocatechol ranged from 0.103 at 30.35°C to 1.095 Pa at 50.15°C.
Executive summary:

In this study, the chemical equilibria of reactions of transalkylation among tert-butylphenols and tert-butylcatechols in the liquid phase were investigated in the temperature range 373-483 K.

The vapour pressure was measured using the transpiration method.

The vapour pressure of the 4-ter-butylpyrocatechol ranged from 0.103 at 30.35°C to 1.095 Pa at 50.15°C.

Description of key information

Vapour pressure experimental values for 4-TBC are available in two peer-reviewed published articles of good reliability (Klimisch 2).

In the first study (Vervkin 2000), the vapour pressure ranged from 0.103 Pa at 30°C to 1.095 Pa at 50°C. this study is considered as the key study.

As supporting data, another experimental study (Steele 1997) shown vapour pressures ranging from 2004 Pa at 165.4°C to 31187 Pa at 243.1°C. The value obtained in this supporting study confirm the key value for chemical safety assessement. Indeed, the vapour pressure measured at high temperature (165 up to 243°C) are higher than the vapour pressures obtained at lower temperature (30 up to 50°C). This observation is consitent with the Clapeyron-Clausius equation.

Key value for chemical safety assessment

Vapour pressure:
0.1 Pa
at the temperature of:
30 °C

Additional information

In addition of these two experiementals vapour pressure values, calculations made with a QSAR program which used 2 methods (Mpbpwin program, Antoine and modified Grain method) are consistent together and with the published values. All this body of information leads to consider 4 -TBC poorly volatile.