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Surface tension

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Reference
Endpoint:
surface tension
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
key 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 limited documentation / justification
Justification for type of information:
SOFTWARE
ACD/Percepta

2. MODEL (incl. version number)
ACD/Labs Release 2017.2

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES : O=C(NCCO)CCCCCCCCCCC(O)CCCCCC

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Algorithms for Calculating Basic Physicochemical Properties

At the heart of the additive-constitutive calculation algorithm of all physicochemical properties in ACD/Percepta lies the presumption that these properties can be estimated using additive atomic or group increments. Apart from molecular weight (MW), which is trivial to calculate, the algorithms may be divided into three general groups:
## Basic macroscopic properties: molar volume (MV), molar refractivity (MR), and parachor (Pr)
## Derived macroscopic properties: density (d), refractive index (n), and surface tension (γ)
## The dielectric constant ε (Permittivity)

Basic macroscopic properties such as molar volume (MV), molar refractivity (MR), and the parachor (Pr) are calculated first for the input structure. The atomic additive increments in such an algorithm depend on the bonds (single, double, aromatic, etc.) of this atom and on neighboring atoms. ACD/Percepta rapidly analyzes the input structure to determine the class of each atom, i.e., whether it is cyclic, aromatic, aliphatic, etc.

The prediction algorithms for density (d), refractive index (n) and surface tension (γ) are founded on well-known physicochemical formula which can be found in literature on physicochemical properties of compounds. They express d, n, and γ as functions of MV, MR, or Pr. Once the MV, MR, or Pr, have been predicted by additive means, it is straightforward to predict d, n, and γ using these formula.

The determination of the additive-constitutive atomic increments for MV, MR, and Pr were obtained internally by ACD/Labs scientists using large experimental databases relating structure to density, refractive index, and surface tension. The MV, MR, and Pr were recalculated from d, n, and γ. These parameters are proprietary information of ACD/Labs, Inc.

The prediction of the dielectric constant ε (permittivity) resembles very closely the prediction of boiling point, which is available as a separate Prediction Module in ACD/Percepta. Senior scientists at ACD/Labs discovered an additive function, which relates the dielectric constant to other macroscopic properties which can be additively treated, such as MV. Once this relationship was discovered, the additive-constitutive atomic increments for this function were obtained using large databases consisting of molecular structures and their observed dielectric constants. Using the function and estimated MV for the input structure, its dielectric constant can be quickly predicted.

Molar Volume, MV

By definition,

MV = MW / d

ACD/Percepta calculates molar volume from additive increments. The additive atomic increments were obtained using a database of density and calculated MW.

Note: The obtained MV value is used as an input parameter for further calculations, but is not displayed in the module interface itself.

Molar Refractivity, MR

The Lorentz-Lorenz equation relates refractive index, density, and refractive index:

MR = (n2 - 1) / (n2 + 2) x MW / d

ACD/Percepta calculates molar refractivity from additive increments. The additive atomic increments were obtained using a database of density, refractive index, and calculated MW.

Note: The obtained MR value is used as an input parameter for further calculations, but is not displayed in the module interface itself.

Parachor, Pr

By definition,

Pr = (MW / d) γ1/4

ACD/Percepta calculates the parachor from additive increments. The additive atomic increments were obtained using a database of density, surface tension, and calculated MW.

Density, d

By definition,

d = MW / MV

ACD/Percepta calculates the density from MW and the calculated molar volume (see above).

Refractive Index, n
By the Lorentz-Lorenz equation,

Refractive Index Formula.gif

ACD/Percepta calculates the refractive index from the molar volume and molar refractivity, both of which are calculated as above.

Surface Tension, γ

By definition,

γ = (Pr / MV)4

ACD/Percepta calculates the surface tension from calculated MV (see above) and calculated Pr (see above).
Guideline:
other: REACH Guidance on QSARs R.6
GLP compliance:
no
Type of method:
other: predicted data
Specific details on test material used for the study:
SMILES : O=C(NCCO)CCCCCCCCCCC(O)CCCCCC
Key result
Surface tension:
0.038 N/m
Temp.:
20 °C
Conc.:
1 g/L
Remarks on result:
other:
Remarks:
QSAR predicted value
Conclusions:
ACD/Labs predicted that test chemical has a surface tension of 0.03765 N/m
Executive summary:

ACD/Labs predicted that test chemical has a surface tension of 0.03765 N/m

Description of key information

Based on the prediction done by ACD labs, the surface tension for test was predicted to be 0.03765 N/m

Key value for chemical safety assessment

Surface tension:
0.038

Additional information

Based on the prediction done by ACD labs, the surface tension for test was predicted to be 0.03765 N/m