Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

Vapour pressure

Administrative data

Endpoint:

vapour pressure

Type of information:

(Q)SAR

Adequacy of study:

supporting study

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
EPIWIN software by US-EPA

2. MODEL (incl. version number)
MPBPVPWIN v1.43

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
S(=O)(=O)(O([Na]))CCCSC(=S)N(C)C

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- The complete test sets of experimental data for (melting point, boiling point and) vapor pressure can be downloaded via the Internet at: http://esc.syrres.com/interkow/EpiSuiteData.htm

5. APPLICABILITY DOMAIN
Estimation accuracy: The accuracy of MPBPWIN's "suggested" VP estimate was tested on a dataset of 3037 compounds with known, experimental VP values between 15 and 30 deg C (the vast majority at 25 or 20 deg C).  The experimental values were taken from the PHYSPROP Database that is part of the EPI Suite. For this test, the CAS numbers were run through MPBPWIN as a standard batch-mode run (using the default VP estimation temperature of 25 deg C) and the batch estimates were compared to PHYSPROP's experimental VP. The plot clearly indicates that the estimation error increases as the vapor pressure (both experimental and estimated) decreases, especially when the vapor pressure decreases below 1x10-6 mm Hg (0.0001333 Pa).
The estimation methodology uses the normal boil point to estimate the liquid-phase vapor pressure. For solids, the melting point is required to convert the liquid-phase vapor pressure to the solid-phase vapor pressure. VP estimation error can be introduced by:
(1) poor Boiling Point estimates or values
(2) poor Melting Point estimates or values (for solids)

The 3037 compound test set contains 1642 compounds with available experimental Boiling points and Melting points. For this subset of compounds, the estimation accuracy statistics are (based on log VP):

  number = 1642
  r2 = 0.949
  std deviation = 0.59
  avg deviation = 0.32

These statistics clearly indicate that VP estimates are more accurate with experimental BP and MP data.

Estimation domain: The intended application domain is organic chemicals. Inorganic and organometallic chemicals generally are outside the 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 complete training sets for MPBPWIN's estimation methodology are not available. Therefore, describing a precise estimation domain for this methodology is not possible. The current applicability of the MPBPWIN methodology is best described by its accuracy in predicting vapor pressure as described above in the accuracy section.

6. ADEQUACY OF THE RESULT
The result calculated for the organic substance sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate seems reasonable. No melting point as such has been determined experimentally, but the determined begining of melting and the calculated melting point do not differ that much. Further, due to the magnitude of the result it is considered as adequate.

Data source

Reference

Title:

EPI Suite Version 4.10

Year:

2012

Bibliographic source:

MPBPVPWIN - three separate methods for VP: Antoine method (1990), modified Grain method (1985) and Mackay method (1985)

Materials and methods

Test guideline

Guideline:

other: REACH guidance on QSARs Chapter R.6

Version / remarks:

May 2008

Principles of method if other than guideline:

Vapor 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).

GLP compliance:

no

Remarks:

(not applicable)

Type of method:

other: QSAR calculation

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

EC Number:

242-644-7

EC Name:

Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

Cas Number:

18880-36-9

Molecular formula:

C6H13NO3S3.Na

IUPAC Name:

sodium 3-[(dimethylcarbamothioyl)sulfanyl]propane-1-sulfonate

Test material form:

not specified

Details on test material:

- Name of test material (as cited in study report) : 1-Propanesulfonic acid, 3-[[(dimethylamino)thioxomethyl]thio]-, sodium salt
- SMILES : S(=O)(=O)(O([Na]))CCCSC(=S)N(C)C

Specific details on test material used for the study:

SMILES: S(=O)(=O)(O([Na]))CCCSC(=S)N(C)C

Results and discussion

Vapour pressure

Vapour pressure 1

Key result

Temp.:

25 °C

Vapour pressure:

0 Pa

Remarks on result:

other: Modified Grain Method (MPBPWIN v1.43) - most relevant for solids

Vapour pressure 2

Temp.:

25 °C

Vapour pressure:

0 Pa

Remarks on result:

other: Mackay Method (MPBPWIN v1.43)

Vapour pressure 3

Temp.:

25 °C

Vapour pressure:

< 0 Pa

Remarks on result:

other: Antoine Method (MPBPWIN v1.43)

Any other information on results incl. tables

MPBPVPWIN predicted that the substance has a vapour pressure = 5.36E-11 PA (modified grain method)

Applicant's summary and conclusion

Conclusions:

The study report describes a scientifically accepted calculation method for the vapour pressure using the US-EPA software MPBPWIN v1.43.No GLP criteria are applicable for the usage of this tool and the QSAR estimation is easily repeatable. The result is adequate for the regulatory purpose.

Executive summary:

The vapour pressure of the substance sodium 3-[(dimethylcarbamothioyl)sulfanyl]propane-1-sulfonate was determined by the computer program MPBPWIN v1.43 (EPIWIN software) by US-EPA (2012). The program calculates the vapour pressure according to three different methods: Antoine, Modified Grain and Mackay. The Modified Grain method is preferentially adopted and therefore the most important one [Lyman, W.J., 1985. In: Environmental Exposure From Chemicals. Volume I., Neely, W.B. and Blau, G.E. (eds), Boca Raton, FL: CRC Press, Inc., Chapter 2].

A boiling point of 590.66 °C, a melting point of 254.95 and an ambient temperature of 25 °C is assumed.

The Antoine Method gives a result of 1.31E-014 Pa, the Mackay Method results in a value of 1.94E-010 Pa and according to the Modified Grain Method the substance has a vapour pressure of 5.36E-011 Pa (most relevant for solids).

The estimation error increases as the vapour pressure decreases, especially when the vapour pressure is below 0.000133Pa, but the calculated value can anyway viewed as indicative of a very low vapour pressure, which is sufficient considering the magnitude of the result.