Reaction mass of dimethyl phosphonate and methyl hydrogenphosphonate and phosphonic acid

Vapour pressure

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

other information

Study period:

18 NOV 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
OECD QSAR toolbox v4.5

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

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
multi-constituent substance with 3 constituents
1. COP(O)=O
2. OP(O)=O
3. COP(=O)OC

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
The vapour pressure is estimated based on the chemical structure of the organic compound. The molecular structure of the chemical compounds is divided into fragments for which fragment coefficients have been determined. These fragment coefficient and the number of incidence of these fragments is taken into account to estimate the vapour pressure. For vapour pressure, a training set of 3037 compounds (for which known, experimental values between 15 and 30 °C were available) were used. Vapour Pressure calculation in QSAR gives standard deviation: 0.59, average deviation = 0.32, R²= 0.949

5. APPLICABILITY DOMAIN
Currently there is no universally accepted definition of model domain. However, users may wish to consider the possibility that property estimates are less accurate for compounds outside the Molecular Weight range of the training set compounds, and/or that have more instances of a given fragment than the maximum for all training set compounds. It is also possible that a compound may have a functional group(s) or other structural features not represented in the training set, and for which no fragment coefficient was developed. These points should be taken into consideration when interpreting model results. The predicted substances (methyl hydrogen phosphonate and dimethyl hydrogen phosphate) are fall into the MW range of the training set compounds. Thus, it is considered to be in the applicability domain of this model. However, phosphonic acid is an inorganic compound. Inorganic compounds are not included in the training data set for the methodology utilized in this program. Therefore, the predicted substance is outside the estimation domain.

Guideline:

other: REACH guidance on QSARs Chapter R.6

Version / remarks:

May 2008

Principles of method if other than guideline:

Software tool(s) used including version: OECD QSAR toolbox v4.5, EPI Suite v4.11
- Model(s) used: MPBPWIN v1.44
- Model description: MPBPWIN estimates vapour pressure (V)) by three separate methods: (1) the Antoine method, (2) the modified Grain method, and (3) the Mackay Method. All three use the normal boiling point to estimates (VP). The Antoine equation uses the parameter delta Zb which is assumed to have the value of 0.97 and the constant C2, which is estimated via Thomson's rule by: C2 = -18 + 0.19 Tb. The modified Grain Method is a modification and significant improvement of the modified Watson method. The Mackay method is based on the method described by Lyman, 1985 and is derived from two chemical classes: hydrocarbons (aliphatic and aromatic) and halogenated compounds (again aliphatic or aromatic). MPBPWIN reports the VP estimate from all three methods. It then reports a "suggested" VP. For solids, the modified Grain method estimates is the suggested VP. For liquids and gases, the suggested VP is the average of the Antoine and the modified Grain estimates. The Mackay methods is not used in the suggested VP because its application is currently limited to its derivation classes.
- Justification of QSAR prediction: see field 'Justification for type of information'.

Specific details on test material used for the study:

multi-constituent substance with 3 constituents
1. COP(O)=O
2. OP(O)=O
3. COP(=O)OC

Temp.:

25 °C

Vapour pressure:

>= 0 - <= 1.53 mm Hg

methyl hydrogen phosphonate

SMILES : COP(O)=O
CHEM :
MOL FOR: C1 H5 O3 P1
MOL WT : 96.02
------------------------ SUMMARY MPBPWIN v1.44 --------------------
Boiling Point: 184.50 deg C (Adapted Stein and Brown Method)
Melting Point: -39.08 deg C (Adapted Joback Method)
Melting Point: -5.93 deg C (Gold and Ogle Method)
Mean Melt Pt : -22.51 deg C (Joback; Gold,Ogle Methods)
Selected MP: -22.51 deg C (Mean Value)

Vapor Pressure Estimations (25 deg C):
(Using BP: 184.50 deg C (estimated))
(MP not used for liquids)
VP: 0.206 mm Hg (Antoine Method)
: 27.5 Pa (Antoine Method)
VP: 0.166 mm Hg (Modified Grain Method)
: 22.1 Pa (Modified Grain Method)
VP: 1.11 mm Hg (Mackay Method)
: 148 Pa (Mackay Method)
Selected VP: 0.186 mm Hg (Mean of Antoine & Grain methods)
: 24.8 Pa (Mean of Antoine & Grain methods)
-------+-----+--------------------+----------+---------
TYPE | NUM | BOIL DESCRIPTION | COEFF | VALUE
-------+-----+--------------------+----------+---------
Group | 1 | -CH3 | 21.98 | 21.98
Group | 1 | -OH (alcohol) | 106.27 | 106.27
Group | 1 | -O- (nonring) | 25.16 | 25.16
Group | 1 | O=P< | 107.23 | 107.23
* | | Equation Constant | | 198.18
=============+====================+==========+=========
RESULT-uncorr| BOILING POINT in deg Kelvin | 458.82
RESULT- corr | BOILING POINT in deg Kelvin | 457.66
| BOILING POINT in deg C | 184.50
-------------------------------------------------------
-------+-----+--------------------+----------+---------
TYPE | NUM | MELT DESCRIPTION | COEFF | VALUE
-------+-----+--------------------+----------+---------
Group | 1 | -CH3 | -5.10 | -5.10
Group | 1 | -OH (alcohol) | 44.45 | 44.45
Group | 1 | -O- (nonring) | 22.23 | 22.23
Group | 1 | O=P< | 50.00 | 50.00
* | | Equation Constant | | 122.50
=============+====================+==========+=========
RESULT | MELTING POINT in deg Kelvin | 234.08
Special-limit| MELTING POINT in deg Kelvin | 234.08
| MELTING POINT in deg C | -39.08
-------------------------------------------------------

Phosphonic acid

SMILES : OP(O)=O
CHEM :
MOL FOR: H3 O3 P1
MOL WT : 82.00
------------------------ SUMMARY MPBPWIN v1.44 --------------------
********************************************************************
* WARNING - The entered structure is an INORGANIC Compound. *
* Inorganic compounds were not included in the training data *
* set for the methodology utilized in this program. Therefore, *
* inorganic compounds are outside the estimation domain. *

********************************************************************
Boiling Point: 480.00 deg C (Adapted Stein and Brown Method)
Melting Point: 75.00 deg C (Adapted Joback Method)
Melting Point: 166.61 deg C (Gold and Ogle Method)
Mean Melt Pt : 120.81 deg C (Joback; Gold,Ogle Methods)
Selected MP: 90.27 deg C (Weighted Value)
Vapor Pressure Estimations (25 deg C):
(Using BP: 480.00 deg C (estimated))
(Using MP: 90.27 deg C (estimated))
VP: 7.15E-013 mm Hg (Antoine Method)
: 9.54E-011 Pa (Antoine Method)
VP: 6.06E-011 mm Hg (Modified Grain Method)
: 8.07E-009 Pa (Modified Grain Method)
VP: 4.2E-008 mm Hg (Mackay Method)
: 5.61E-006 Pa (Mackay Method)
Selected VP: 6.06E-011 mm Hg (Modified Grain Method)
: 8.07E-009 Pa (Modified Grain Method)
Subcooled liquid VP: 2.58E-010 mm Hg (25 deg C, Mod-Grain method)
: 3.44E-008 Pa (25 deg C, Mod-Grain method)
-------+-----+--------------------+----------+---------
TYPE | NUM | BOIL DESCRIPTION | COEFF | VALUE
-------+-----+--------------------+----------+---------
Group | 2 | -OH (alcohol) | 106.27 | 212.54
Group | 1 | O=P< | 107.23 | 107.23
Corr | 1 | Inorganic | 700.00 | 700.00
* | | Equation Constant | | 198.18
=============+====================+==========+=========
RESULT-uncorr| BOILING POINT in deg Kelvin | 1217.95
RESULT- corr | BOILING POINT in deg Kelvin | 866.22
Special-Limit| BOILING POINT in deg Kelvin | 753.16
| BOILING POINT in deg C | 480.00
-------------------------------------------------------
-------+-----+--------------------+----------+---------
TYPE | NUM | MELT DESCRIPTION | COEFF | VALUE
-------+-----+--------------------+----------+---------
Group | 2 | -OH (alcohol) | 44.45 | 88.90
Group | 1 | O=P< | 50.00 | 50.00

Corr | 1 | Inorganic | 300.00 | 300.00
* | | Equation Constant | | 122.50
=============+====================+==========+=========
RESULT | MELTING POINT in deg Kelvin | 561.40
Special-limit| MELTING POINT in deg Kelvin | 348.16
| MELTING POINT in deg C | 75.00
-------------------------------------------------------

dimethyl hydrogen phosphate

Experimental Database Structure Match:
Name : DIMETHYL PHOSPHONATE
CAS Num : 000868-85-9
Exp MP (deg C): -60
Exp BP (deg C): 170.5
Exp VP (mm Hg): 1.81E+00
(Pa ): 2.41E+002
Exp VP (deg C): 25
Exp VP ref : BUTROW,AB ET AL. (2009)
SMILES : COP(=O)OC
CHEM :
MOL FOR: C2 H7 O3 P1
MOL WT : 110.05
------------------------ SUMMARY MPBPWIN v1.44 --------------------

Boiling Point: 131.51 deg C (Adapted Stein and Brown Method)
Melting Point: -66.40 deg C (Adapted Joback Method)
Melting Point: -36.87 deg C (Gold and Ogle Method)
Mean Melt Pt : -51.64 deg C (Joback; Gold,Ogle Methods)
Selected MP: -51.64 deg C (Mean Value)
Vapor Pressure Estimations (25 deg C):
(Using BP: 170.50 deg C (exp database))
(MP not used for liquids)
VP: 1.66 mm Hg (Antoine Method)
: 222 Pa (Antoine Method)
VP: 1.39 mm Hg (Modified Grain Method)
: 185 Pa (Modified Grain Method)
VP: 2.11 mm Hg (Mackay Method)
: 282 Pa (Mackay Method)
Selected VP: 1.53 mm Hg (Mean of Antoine & Grain methods)
: 203 Pa (Mean of Antoine & Grain methods)
-------+-----+--------------------+----------+---------
TYPE | NUM | BOIL DESCRIPTION | COEFF | VALUE
-------+-----+--------------------+----------+---------
Group | 2 | -CH3 | 21.98 | 43.96
Group | 2 | -O- (nonring) | 25.16 | 50.32
Group | 1 | O=P< | 107.23 | 107.23
* | | Equation Constant | | 198.18
=============+====================+==========+=========
RESULT-uncorr| BOILING POINT in deg Kelvin | 399.69
RESULT- corr | BOILING POINT in deg Kelvin | 404.67
| BOILING POINT in deg C | 131.51
-------------------------------------------------------
-------+-----+--------------------+----------+---------
TYPE | NUM | MELT DESCRIPTION | COEFF | VALUE
-------+-----+--------------------+----------+---------
Group | 2 | -CH3 | -5.10 | -10.20
Group | 2 | -O- (nonring) | 22.23 | 44.46
Group | 1 | O=P< | 50.00 | 50.00
* | | Equation Constant | | 122.50
=============+====================+==========+=========

RESULT | MELTING POINT in deg Kelvin | 206.76
Special-limit| MELTING POINT in deg Kelvin | 206.76
| MELTING POINT in deg C | -66.40
-------------------------------------------------------

Conclusions:

The vapour pressure of the test item has been determined as a range as it is a multi-constituent substance. The vapour pressure of test item is in the range of greater than 6.06E-11 to less than 1.53 mmHg by US EPA software MPBPVP v1.44.

Executive summary:

The vapour pressure of the test item has been determined as a range as it is a multi-constituent substance. The vapour pressure of test item is in the range of greater than 6.06E-11 to less than 1.53 mmHg by US EPA software MPBPVP v1.44.

Reference 2

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Version / remarks:

Cited as Directive 92/69/EEC, A.4

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

dynamic method

Temp.:

20 °C

Vapour pressure:

1.35 hPa

Remarks on result:

other: calculated by using the regressed parameters of the Antoine-Equation

Temp.:

25 °C

Vapour pressure:

1.9 hPa

Remarks on result:

other: calculated by using the regressed parameters of the Antoine-Equation

Temp.:

50 °C

Vapour pressure:

8.99 hPa

Remarks on result:

other: calculated by using the regressed parameters of the Antoine-Equation

Temp.:

24.88 °C

Vapour pressure:

1.89 hPa

Remarks on result:

other: calculated by using the regressed parameters of the Antoine-Equation

Temp.:

170.51 °C

Vapour pressure:

1 050.81 hPa

Remarks on result:

other: calculated by using the regressed parameters of the Antoine-Equation

Parameters of Antoine-Equation:

A = 7.8264

B = 1924.4

C = 230 (fixed)

Interpolation range: T_m < T < 170.5 °C (T_m = Melting Point [°C])

Mean Deviation = 4.89%

Table 1. Data

temperature [V]	temperature [°C]	temperature [1/K*10000]	p  [hPa]	regression [hPa]	deviation [¿p/p*100%]
0.25285	24.88	33.6	1.8	1.9	4.7
0.46258	45.86	31.3	7.9	7.1	-11.5
0.83437	82.96	28.1	50.8	47.6	-6.8
1.116145	111.02	26.0	158.3	152.5	-3.8
1.3135	130.66	24.8	312.8	309.5	-1.1
1.53463	152.65	23.5	624.1	627.1	0.5
1.71416	170.51	22.5	1005.2	1050.9	4.3
0.272065	26.81	33.3	1.9	2.2	11.7
0.31951	31.55	32.8	3.0	2.9	-1.9
0.384505	38.06	32.1	4.8	4.4	-8.1
0.73954	73.51	28.8	31.6	30.6	-3.2
1.20794	120.16	25.4	210.3	214.1	1.8
1.413195	140.58	24.2	412.1	429.9	4.1

Executive summary:

Vapour pressure of dimethyl phosphonate was determined according to EU Method A.4 (dynamic methond). The vapour pressure is 1.35 hPa at 20 °C. (Olf, Bayer AG, 2001)

Description of key information

4.6.1 Bayer AG, 2001: EU Method A.4; dimethyl phosphonate; 1.9 hPa at 25 °C

EPIWIN(MPBPVP v1.44): QSAR calculation; 25 °C; methyl hydrogen phosphonate: 0.186 mmHg(0.25 hPa); phosphonic acid: 6.06E-11 mmHg(8.074E-11 hPa); dimethyl phosphonate: 1.53 mmHg(2.04 hPa) 

As a key result, the highest vapour pressure of one constituent (dimethyl phosphonate) was selected as worst case approach (2.04 hPa) for the phosphonic ester residue.

Key value for chemical safety assessment

Vapour pressure:

2.04 hPa

at the temperature of:

25 °C