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Environmental fate & pathways

Henry's Law constant

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Reference
Endpoint:
Henry's law constant
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: (Q)SAR method with established scientific validity. Terephthalic acid falls within the applicability domain of the model.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
GLP compliance:
no
Remarks:
Not relevant (calculated endpoint).

Table 1: Henry's Law constants predicted for terephthalic acid using HENRYWIN v3.20

HENRYWIN v3.20

1,4-benzenedicarboxylic acid; SMILES: O=C(O)c(ccc(c1)C(=O)O)c1

Method 1: Bond estimation

Pa m3/mole at 25°C

2.21 × 10‑7

Method 2: Group estimation

Pa m3/mole at 25°C

3.93 × 10‑8

Conclusions:
HENRYWIN v.3.20 predicts Henry's Law constants of 2.21E-7 and 3.93E-8 Pa m3/mole for terephthalic acid at 25 degrees C by the bond estimation and group estimation methods, respectively.
Executive summary:

Henry's Law constants for terephthalic acid were estimated using the HENRYWIN v3.20 QSAR model available from the US EPA. Estimated Henry's Law constants of 2.21E-7 and 3.93E-8 Pa m3/mole at 25 degrees C were obtained by the bond estimation and group estimation methods, respectively.

Description of key information

Henry's Law constants for terephthalic acid were estimated using the HENRYWIN v3.20 QSAR model available from the US EPA. Estimated Henry's Law constants of 2.21E-7 and 3.93E-8 Pa m3/mole at 25 degrees C were obtained by the bond estimation and group estimation methods, respectively.

Key value for chemical safety assessment

at the temperature of:
20 °C

Additional information

After conversion to log10, the estimated Henry's Law constants (HLc) for terephthalic acid range from ca. -7 to -8. According to the tables presented in Appendix II of Part II of the Technical Guidance Document on Risk Assessment (European Commission, 2003), the threshold value of log10 HLc at which significant (=/>10%) air-stripping occurs under conditions of forced aeration during waste-water treatment is +1.0, and no air-stripping occurs at log10 HLc values =/<1.0. Both HLc estimates provided by HENRYWIN v3.20 indicate that terephthalic acid is unlikely to partition from aqueous systems to the atmosphere.