p-(trifluoromethoxy)phenyl isocyanate

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

other information

Study period:

14 OCT 2022

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11

2. MODEL (incl. version number)
MPBPVP v1.44

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
FC(F)(F)Oc1ccc(cc1)N=C=O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Vapour Pressure is estimated by three methods; all three methods use the boiling point. The first is the Antoine method. The second is the modified Grain method. The third is the Mackay method. For solids, a melting point is required to adjust the vapour pressure from a subcooled (supercooled) liquid to a solid. Data entry allows measured BP and MP to be used; when entered, the measured values are used instead of the estimated values. The preferred VP method for solids is the Modified Grain method, although the Antoine method in this program is nearly as good because it uses the exact same methodology to convert super-cooled VP to solid VP. For liquids, the mean of the Grain and Antoine methods is preferred. The applicability of the Mackay method is limited to a reduced number of chemical classes, so it is generally not preferred.
For vapour pressure, a training set of 3037 compounds (for which known, experimental values between 15 and 30 deg C are available) was used. Vapour Pressure calculation in QSAR gives standard deviation of 0.59, average deviation of 0.32 an R² of 0.949

5. APPLICABILITY DOMAIN
The applicability domain is described by the range of the molecular weight of the training set as well as the identification and number of instances of a given fragment. The number of instances of a given fragment is compared to the maximum for all training set compounds. If this number exceeds the maximum number or a fragment is not identified, the estimate of a substance is regarded to be less accurate. If a compound has (a) functional group(s) or other structural features not represented in the training set, and for which no fragment coefficient was developed, the estimates is regarded less accurate as well. The predicted substance falls into the MW range of the training set compounds. Thus, it is considered to be in the applicability domain of this model.

Guideline:

other: REACH guidance on QSARs R.6

Version / remarks:

May 2008

Principles of method if other than guideline:

Software tool(s) used including version: EPI Suite v4.11
- Model(s) used: MPBPWIN v1.44
- Model description: MPBPWIN estimates vapour pressure (VP) by three separate methods.
1. Antoine method: This method uses the Antoine equation which describes the relation between vapour pressure and temperature.
2. Modified Grain method: This method uses the Watson correlation, which describes the temperature dependence of the heat of vaporisation.
3. Mackay method: This method is derived from two chemical classes: hydrocarbons (aliphatic and aromatic) and halogenated compounds (again aliphatic and aromatic). The Mackay method is generally not proposed because it is not applicable to as many chemical classes as the other methods.

All three methods use the boiling point. All methods are applicable for the determination of the vapour pressure of gases and liquids. For a solid substance the melting point is required for the calculation to adjust the vapour pressure from a liquid to a solid using the modified Grain method. If no boiling point/ melting point is entered on the data entry screen MPBPWIN uses the boiling point/ melting point estimated by the program. Calculation of melting and boiling point is based on structure fragments with its correction factors and coefficient values. When a boiling point/ melting point is entered on the data entry screen, MPBPWIN uses it for calculation.

The Modified Grain Method is applicable to solids, liquids and gases and uses the normal boiling point to estimate VP. The method is desrcibed in chapter 2 of Lyman (1985). This method is a modification and significant improvement of the modified Watson method. the equations are: ln P(l) = ((Kpln(RTb)/Zb)*[l-((3- 2Tp)[E]m)/Tp) - (2m(3-2Tp)[Em-1]*lnTp)], where P(l) = liquid vapour pressure (atm); Kf = structural factor (see Handbook of Chemical Property Estimation Methods); R = gas constant (82.057 cm³ atm/mol K); Z = compressibility factor ( = 0.97), Tb = normal boiling point (K); T = temperature (K); Tp = T/Tb; and m = 0.4133 - 0.2575 Tp. For solids, a second term is added to Equation 21 so that: ln P(s) = lnP (l) + Ln P (s), where ln P(s) = 0.6 ln (RTm) [1-((3-2Tp)[E]m)/Tpm) - (2m(3-2Tpm)[Em- 1]*lnTpm)], where P(s) = solid vapour pressure (atm); P 8s) = decrease in slid vapour pressure vs. that of supercooled liquid (atm); Tm = melting point (K); Tpm = T/Tm; and m = 0.4133 - 0.2575 Tpm. The Kf structural factors are available in Chapter 14 of Lyman et al. (1990), the variation of this parameter is related to chemical class and is small (roughly 0.99 - 1.2), so large errors in its selection are unlikely (Lyman, 1985). The modified Grain method may be the best all-around VP estimation method currently available. For vapour pressure, a training set of 3037 compounds (for which known, experimental values between 15 and 30 deg C were available) were used.

- Justification of QSAR prediction: see field 'Justification for type of information'.

Temp.:

25 °C

Vapour pressure:

142 Pa

Remarks on result:

other: modified Grain method using experimental boiling point of 176°C (user entered)

Experimental Database Structure Match: no data

SMILES : FC(F)(F)Oc1ccc(cc1)N=C=O
CHEM :
MOL FOR: C8 H4 F3 N1 O2
MOL WT : 203.12
------------------------ SUMMARY MPBPWIN v1.44 --------------------

Boiling Point: 185.95 deg C (Adapted Stein and Brown Method)

Melting Point: -2.92 deg C (Adapted Joback Method)
Melting Point: -5.09 deg C (Gold and Ogle Method)
Mean Melt Pt : -4.00 deg C (Joback; Gold,Ogle Methods)
Selected MP: -4.00 deg C (Mean Value)

Vapor Pressure Estimations (25 deg C):
(Using BP: 176.00 deg C (user entered))
(MP not used for liquids)
VP: 1.28 mm Hg (Antoine Method)
: 170 Pa (Antoine Method)
VP: 1.06 mm Hg (Modified Grain Method)
: 142 Pa (Modified Grain Method)
VP: 1.64 mm Hg (Mackay Method)
: 219 Pa (Mackay Method)
Selected VP: 1.17 mm Hg (Mean of Antoine & Grain methods)
: 156 Pa (Mean of Antoine & Grain methods)

 

-------+-----+--------------------+----------+---------
TYPE | NUM | BOIL DESCRIPTION | COEFF | VALUE
-------+-----+--------------------+----------+---------
Group | 1 | >C< | 4.50 | 4.50
Group | 1 | =C= | 26.15 | 26.15
Group | 3 | -F | 0.13 | 0.39
Group | 1 | -O- (nonring) | 25.16 | 25.16
Group | 1 | =O (other) | -10.50 | -10.50
Group | 4 | CH (aromatic) | 28.53 | 114.12
Group | 2 | -C (aromatic) | 30.76 | 61.52
Group | 1 | -N=C=O(to arom) | 41.00 | 41.00
* | | Equation Constant | | 198.18
=============+====================+==========+=========
RESULT-uncorr| BOILING POINT in deg Kelvin | 460.52
RESULT- corr | BOILING POINT in deg Kelvin | 459.11
| BOILING POINT in deg C | 185.95
-------------------------------------------------------

-------+-----+--------------------+----------+---------
TYPE | NUM | MELT DESCRIPTION | COEFF | VALUE
-------+-----+--------------------+----------+---------
Group | 1 | >C< | 46.43 | 46.43
Group | 1 | =C= | 17.78 | 17.78
Group | 3 | -F | -15.78 | -47.34
Group | 1 | -O- (nonring) | 22.23 | 22.23
Group | 1 | =O (other) | 2.08 | 2.08
Group | 4 | CH (aromatic) | 8.13 | 32.52
Group | 2 | -C (aromatic) | 37.02 | 74.04
Group | 1 | -N=C=O(to arom) | 0.00 | 0.00
* | | Equation Constant | | 122.50
=============+====================+==========+=========
RESULT | MELTING POINT in deg Kelvin | 270.24
| MELTING POINT in deg C | -2.92
-------------------------------------------------------

Conclusions:

The vapour pressure of the test item was calculated to be 1.06 mmHg (142 Pa) using the US- EPA software MPBPWIN v1.44.

Executive summary:

The vapour pressure of the test item was calculated to be 1.06 mmHg (142 Pa) using the US- EPA software MPBPWIN v1.44 (modified Grain method using experimental boiling point of 176°C (user entered)). The prediction falls in the applicability domain of this model.

Description of key information

The vapour pressure of TFMOPI was predicted using the QSAR calculation of the Estimation Programm Interface EPI-Suite v4.1. The experimentally determined boiling point of 176°C at 1013 hPa was taken into account for estimation. Using the modified Grain method, the vapour pressure was estimated to be 142 Pa at 25°C. The predicted value can be considered reliable yielding a useful result for further assessment.

Key value for chemical safety assessment

Vapour pressure:

142 Pa

at the temperature of:

25 °C