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Physical & Chemical properties

Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
(Q)SAR
Remarks:
With additional confirmation by experimental data
Adequacy of study:
key study
Study period:
June 2017
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 limited documentation / justification
Justification for type of information:
Since (a) the active component (C-Quart) cannot be isolated without decomposition and does not exist in a pure form and (b) testing the manufactured substance (active component in water/propylene glycol) would largely be dominated by the vapour pressure of water, the vapour pressure was estimated by QSAR using MPBPVP software (version 1.43) as implemented in U.S.EPA’s EpiSuite™ with supporting information coming from an experimental study using headspace GC/MS.
Principles of method if other than guideline:
Two approaches were followed:
- Well-documented, valid QSAR
- Experimental determination using headspace GC/MS
GLP compliance:
no
Type of method:
other: QSAR
Remarks:
With additional confirmation by experimental data
Specific details on test material used for the study:
Test material information refers to the active component, for which QSAR was applied.
SMILES protonated form: CC(O)C[N+](C)(C)CCCCCC[N+](C)(C)CC(C)O
SMILES used in EpiSuite™: CC(O)CN(C)(C)CCCCCCN(C)(C)CC(C)O
EpiSuite™ is unable to process protonated SMILES notations. Therefore, a transformed SMILES notation was entered, ensuring that the critical fragment (N 5+) is correctly identified.
Key result
Test no.:
#1
Temp.:
25 °C
Vapour pressure:
< 0.001 Pa

QSAR

The following table shows the output of the MPBPVP calculations.

Selected vapour pressure: 1.59 x 10-17Pa

SMILES: CC(O)CN(C)(C)CCCCCCN(C)(C)CC(C)O

MOL FOR: C16 H38 N2 O2

MOL WT : 290.49

 

Boiling Point: 674.91 deg C (Adapted Stein and Brown Method)

Melting Point: 349.84 deg C (Adapted Joback Method)

Melting Point: 280.42 deg C (Gold and Ogle Method)

Mean Melt Pt : 315.13 deg C (Joback; Gold,Ogle Methods)

Selected MP: 294.30 deg C (Weighted Value)

Vapor Pressure Estimations (25 deg C):

(Using BP: 674.91 deg C (estimated) and Using MP: 294.30 deg C (estimated))

VP: 2.85E-025 Pa (Antoine Method)

VP: 1.59E-017 Pa (Modified Grain Method)

VP: 4.67E-013 Pa (Mackay Method)

Selected VP: 1.59E-017 Pa (Modified Grain Method)

Subcooled liquid VP: 1.58E-014 Pa (25 deg C, Mod-Grain method)

Boiling point estimates

TYPE

NUM

FRAGMENT

 

COEFF

VALUE

Group

6

-CH3

 

21.98

131.88

Group

8

-CH2

 

24.22

193.76

Group

2

-CH

 

11.86

23.72

Group

2

-OH (secondary)

 

80.63

161.26

Group

2

>N< (+5)

 

340.00

680.00

Equation constant

198.18

RESULT-uncorr BOILING POINT in deg Kelvin

1388.80

RESULT-corr BOILING POINT in deg Kelvin

948.07

BOILING POINT in deg C

674.91

Melting point estimates

TYPE

NUM

FRAGMENT

 

COEFF

VALUE

Group

6

-CH3

 

-5.10

-30.60

Group

8

-CH2

 

11.27

90.16

Group

2

-CH

 

12.64

25.28

Group

2

-OH (secondary)

 

44.45

88.90

Group

2

>N< (+5)

 

340.00

680.00

Equation constant

122.50

RESULT MELTING POINT in deg Kelvin

976.24

RESULT-limit MELTING POINT in deg Kelvin

623.00

MELTING POINT in deg C

349.84

MPBPVP estimates a vapour pressure for the active component of the manufactured substance (C-Quart) of 1.59 x 10-17Pa based on the most appropriate modified Grain method. This value is between the values estimated with the other two (less well suited) methods (4.67 x 10-13Pa (Mackay method) and 2.85 x 10-25Pa (Antoine Method)). The boiling points and melting points entering the estimate are different from the ones entered in this dossier, since the values reported here are for neat C-Quart, while those reported in this dossier are for the substance as manufactured and placed on the market.

MPBPVP does not correctly represent C-Quart with the two positively charged nitrogen atoms, since the model is not able to properly represent the structure. However, the software correctly identifies the fragment as ‘>N< (+5)’. It is also obvious that this fragment is largely responsible for the high melting and boiling points estimated. As is evident from the extract of the help file of MPBPVP, coefficients for this fragment were derived by Syracuse Research Corporation from representative compounds after the original derivation. No further details on these evaluations are available.

While these estimates are therefore somewhat uncertain, it appears safe to assume that the vapour pressure of C-Quart is below 1 x 10-3Pa. This upper end, which is 14 orders of magnitude higher than the estimated vapour pressure, is chosen for risk assessment purposes.

Vapour pressure = 0.001 Pa

EXPERIMENTAL

No traces of the active component of the manufactured substance (15.5 % active component) were found in the gas-phase above the solution. There is no volatile compound to detect, thus confirming the very low value of the vapour pressure estimated by QSAR.

Conclusions:
The vapour pressure of the active component of the test item is < 0.001 Pa at 25 °C.
Executive summary:

Due to the nature of the substance, the vapour pressure was estimated with MPBPVP (v. 1.43), a valid well-documented model. The vapour pressure was estimated to be 1.59 x 10-17 Pa at 25 °C. Due to the uncertainties involved, an upper end estimate of < 0.001 Pa (0.001 Pa used for risk assessment purposes) was derived. The low degree of volatilisation is supported by headspace GC/MS analyses, which did not find any traces of the active component of the manufactured substance (15.5 % active component) in the gas-phase above the solution.

Description of key information

Since the active component (C-Quart) cannot be isolated without decomposition and does not exist in a pure form, the vapour pressure was estimated with MPBPVP (v. 1.43), a valid well-documented model. The vapour pressure was estimated to be 1.59 x 10-17 Pa at 25 °C. Due to the uncertainties involved, an upper end estimate of < 0.001 Pa was derived. A value of 0.001 Pa is used for risk assessment purposes.

The low degree of volatilisation is supported by headspace GC/MS analyses, which did not find any traces of the active component of the manufactured substance (15.5 % active component) in the gas-phase above the solution.

Key value for chemical safety assessment

Vapour pressure:
0.001 Pa
at the temperature of:
25 °C

Additional information