Naphthenic acids, bismuth salts

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE
EPISuite v. 1.43

2. MODEL (incl. version number)
MPBPWIN, embedded within EPISuite version 1.43, established by US EPA

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See smiles codes of various naphthenic acids used in section Any other information on results incl. tables

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Estimation of vapour pressure is calculated by three methods, being the Antoine method (see Chapter 14 of W.J. Lyman's book "Handbook of Chemical Property Estimation Methods", Washington, DC: American Chemical Society, 1990), the modified Grain method (see page 31 of Neely and Blau's Environmental Exposure from Chemicals, Volume I, CRC Press, 1985) and the Mackay method (see page 31-2 of Neely and Blau's Environmental Exposure from Chemicals, Volume I, CRC Press, 1985). The model MPBPWIN reports a suggested vapour pressure based on the modified Grain method for solids, but an average of the Antoine method and modified Grain method for gases and liquids, applicable here. The boiling point is used as a descriptor in the Antoine and Mackay method. The melting point is used as a descriptor in the modified Grain method.
Statistical characteristics of the model: N = 3037, the coefficient of determination, R² = 0.914

5. APPLICABILITY DOMAIN
No real applicability domain is defined, but the test data set is based on a molecular weight of 16.04 - 943.17 for organic substances. Comparability between values is expected being more reliable within a group of structurally similar substances sharing same functional groups. The estimation error increases as vapour pressure decreases, especially for values lower than 1.33E-04 Pa.

6. ADEQUACY OF THE RESULT
The selection of components in naphthenic acids used here are within the applicability domain described above (the molecular weight range of the mixture = 116.1 - 432.7) and the substance does not contain any other functional groups than the molecules in the test set – i.e. aliphatics and carboxy acids as functional groups). Hence, the predicted value can be considered reliable.

Qualifier:

according to guideline

Guideline:

other: REACH guidanc eon QSARs

Principles of method if other than guideline:

Vapour pressure was estimated using the validated EPISuite modelling tool (US EPA). The module MPBPWIN v 1.43 has been used. The vapour pressure is the average of the vapor pressure obtained by the Antoine method and the modified Grain method, and is based on data entry of SMILES (Simplified Molecular Input Line Entry System) notations.
Vapour Pressure is estimated by three methods; all three methods use the boiling point. The first is the Antoine method (see Chapter 14 of W.J. Lyman's book "Handbook of Chemical Property Estimation Methods", Washington, DC: American Chemical Society, 1990). The second is the modified Grain method (see page 31 of Neely and Blau's Environmental Exposure from Chemicals, Volume I, CRC Press, 1985). The third is the Mackay method (see page 31-2 of Neely and Blau's Environmental Exposure from Chemicals, Volume I, CRC Press, 1985).
Estimation of the vapour pressure is based on the boiling point.

GLP compliance:

no

Type of method:

other: MPBPWIN, v.1.43 assessment

Test no.:

#1

Temp.:

20 °C

Vapour pressure:

< 1 Pa

In the EPISUITE program, an experimental vapour pressure is indicated if present in the database. Therefore, for the first three acids estimated the tool provided also an experimental vapour pressures, taken from literature sources. By comparing these three experimental vapour pressure values with the vapour pressure values calculated by the model, it is obvious that the tool is rather conservative, overestimating the real vapour pressure of the components. Furthermore, it should be considered that the naphthenic acids relevant for the target substance are mainly showing a carbon number distribution of C9 – C15 and thus vapour pressure of the components are expected being lower than 1 Pa at least.

The results provided by the model are summarized in following table:

 

C-number	SMILES	Mw	Vapour pressure calc. (Pa)	Vapour pressure exp. (Pa)
C6	C(=O)(O)CCCCC	116,16	37,1	5,8
C7	C(=O)(O)CCCCCC	130,19	15,6	1,43
C8	C(=O)(O)CCCCCCC	144,22	6,51	0,495
C8	C(=O)(O)CCC1CCCC1	142,2	3,39
C9	C(=O)(O)CCCC(C)CCC	158,24	3,26
C10	C(=O)(O)CCCC(CCC)CC	172,27	1,3
C10	C(=O)(O)CCC1C(CC)CCC1	170,25	0,719
C11	C(=O)(O)CCC1C(CCC)CCC1	184,28	0,336
C12	C(=O)(O)CCC1C(CCC)CCCC1	198,31	0,145
C12	C(=O)(O)CCC1C(CCCC)CCC1	198,31	0,155
C12	C(=O)(O)CCC1C2C(C)CCC2CC1	196,29	0,17
C13	C(=O)(O)CCC1C(C2CCCC2)CCC1	210,32	0,0583
C13	O=C(O)CCC2CCCC1CCC(C)C12	210,32	0,0762
C14	O=C(O)C1C(CCCCCCCC)CCC1	226,36	0,0376
C14	C(=O)(O)CCC1CC(C2C(C)CCC2)CC1	224,35	0,036
C14	C(=O)(O)CCCC1C2C(CC)CCC2CC1	224,35	0,0407
C15	C(=O)(O)CCCCC(CCCCCC)CCC	242,41	0,0302
C15	C(=O)(O)CCC1C(CC(CCC)CC)CCC1	240,39	0,029
C15	C(=O)(O)CCC1C(CC2CC(C)CC2)CCC1	238,37	0,0189
C15	O=C(O)CCC1CCC2CCCC(CC)C2C1	238,37	0,0189
C15	C(=O)(O)CCCC1C2C3C(CC2CC1)CCC3C	250,38	0,0121
C16	C(=O)(O)CCC1C(CCCCCCCC)CCC1	254,42	0,0104
C16	C(=O)(O)CCC1CC(C2C(CCC)CCC2)CC1	252,4	0,01
C16	C(=O)(O)C1C(CCC2C(C)CCCC2)CCCC1	252,4	0,0089
C16	C(=O)(O)CC1C2C(CC3CCCC3)CCC2CC1	250,38	0,00898
C17	C(=O)(O)CCC1C(CCCCCCCCC)CCC1	268,44	0,0055
C17	C12(C3C(CC(=O)O)CCC3CC1)C1C(CCC1)CC2	262,4	0,00631
C18	C(=O)(O)CCC1C(CC(CCCC)CCC)CCCC1	282,47	0,00402
C18	C(=O)(O)CCCCC1C2C(C3CCCC3)CCC2CC1	278,44	0,00249
C19	C(=O)(O)CCCCC1C2C(C(CCC)CC)CCC2CC1	294,48	0,00242
C19	C(=O)(O)CC1CC(CC(CCC2CCCC2)CCC)CC1	294,48	0,00178
C25	C(=O)(O)CCCC(CCC1C(CCC2C(C)CCCC2)CCCC1)CCC	378,64	3,75E-05
C30	C(=O)(O)CCC(CCCC1C(CCC2C(CCCCCC)CCCC2)CCCC1)CCC	448,78	1,29E-06
C30	C(=O)(O)CCCCCCC1C(CCC2C(CCCC3CCCCC3)CCCC2)CCCC1	446,76	6,30E-07
C30	O=C(O)CCCCC(CC)CCC1CC2CCCC3CC(CCC(CC)CC)CC(C1)C23	446,76	1,27E-21
C30	O=C(O)CCCC(CCC)CCCC1CCC2CC(CCC2C1)CC3CCCC(C)C3	432,74	1,41E-21

Validity of the model

1. Endpoint: vapour pressure

2. Algorithm: Estimation of vapour pressure is calculated by three methods, being the Antoine method (see Chapter 14 of W.J. Lyman's book "Handbook of Chemical Property Estimation Methods", Washington, DC: American Chemical Society, 1990), the modified Grain method (see page 31 of Neely and Blau's Environmental Exposure from Chemicals, Volume I, CRC Press, 1985) and the Mackay method (see page 31-2 of Neely and Blau's Environmental Exposure from Chemicals, Volume I, CRC Press, 1985). The model MPBPWIN reports a suggested vapour pressure based on the modified Grain method for solids, but an average of the Antoine method and modified Grain method for gases and liquids, applicable here. The boiling point is used as a descriptor in the Antoine and Mackay method. The melting point is used as a descriptor in the modified Grain method.

3. Applicability domain: No real applicability domain is defined, but the test data set is based on a molecular weight of 16.04 - 943.17 for organic substances. Comparability between values is expected being more reliable within a group of structurally similar substances sharing same functional groups. The estimation error increases as vapour pressure decreases, especially for values lower than 1.33E-04 Pa.

4. Statistical characteristics of the model: N = 3037, the coefficient of determination, R² = 0.914

5. Mechanistic interpretation: The model relates to stuctures/functional groups in a substance, affecting the boiling point. Based on smiles codes melting/boiling points are estimated and from there, the vapour pressure is calculated.

Adequacy of the prediction: The selection of components in naphthenic acids used here are within the applicability domain described above (the molecular weight range of the mixture = 116.1 - 432.7) and the substance does not contain any other functional groups than the molecules in the test set – i.e. aliphatics and carboxy acids as functional groups). Hence, the predicted value can be considered reliable.

Conclusions:

The vapour pressure of naphthenic acids, considered being the most volatile component in the UVCB-substance, is expected being <1 Pa at 20 °C. The main component bismuth naphthenate is expected having a negligible vapour pressure, considering a three times higher molecular weight than any of the naphthenic acids. Furthermore, the naphthenic acids present in the product as anions are mainly in the range of C10 to C15 and the content of free naphthenic acids is approx. 10% only; thus the product vapour pressure is estimated being below 0.1 Pa.

Description of key information

The vapour pressure of naphthenic acids, considered being the most volatile component in the UVCB-substance, is expected being <1 Pa at 20 °C. The main component bismuth naphthenate is expected having a negligible vapour pressure, considering a three times higher molecular weight than any of the naphthenic acids. Furthermore, the naphthenic acids present in the product as anions are mainly in the range of C10 to C15 and the content of free naphthenic acids is approx. 10% only; thus the product vapour pressure is estimated being below 0.1 Pa.

Key value for chemical safety assessment

Vapour pressure:

0.1 Pa

at the temperature of:

20 °C