4-(1,1,3,3-tetramethylbutyl)phenol

Henry's Law constant

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

Henry's law constant

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Meets generally accepted scientific standards, well documented and accepted for assessment.

Qualifier:

no guideline available

Principles of method if other than guideline:

Dynamic equilibrium system experiment:
Henry’s Law Constants (HLC, M atm^-1) were determined for tertiary octylphenol (t-OP) and Gamma-hexachlorocyclohexane (Gamma-HCH, reference substance) in artificial seawater over a temperature range 278–298 K using a dynamic equilibrium system. Trace organic substances present in the gas phase were trapped by tandem XAD-2 cartridges and extracted with a soxhlet extractor. The extracts were derivatived with N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA), and then analyzed with GC-MS in the selective ion mode.

GLP compliance:

not specified

H:

2 008 other: M/atm

Temp.:

4.85 °C

Atm. press.:

1 013 hPa

H:

1 277 other: M/atm

Temp.:

9.85 °C

Atm. press.:

1 013 hPa

H:

566 other: M/atm

Temp.:

14.85 °C

Atm. press.:

1 013 hPa

H:

574

Temp.:

19.85 °C

Atm. press.:

1 013 hPa

H:

195

Temp.:

24.85 °C

Atm. press.:

1 013 hPa

- The recovery for the extraction and clean-up was obtained at 73.5% +/- 9.0 % and 70.0% +/- 7.4% fort-OP and Gamma-HCH, respectively.

-The absolute amounts oft-OP and Gamma-HCH detected on the cartridges were <1% of the total mass of the substances in the water phase.

Conclusions:

The Henry Law constant for t-OP is relatively high, indicating that significant deposition of t-OP from the atmosphere to surface waters can take place.

Executive summary:

Henry’s Law Constants (HLC, M atm^-1) were determined for tertiary octylphenol (t-OP) and Gamma-hexachlorocyclohexane (Gamma-HCH, reference substance) in artificial seawater over a temperature range 278–298 K using a dynamic equilibrium system. Trace organic substances present in the gas phase were trapped by tandem XAD-2 cartridges and extracted with a soxhlet extractor. The extracts were derivatived with N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA), and then analyzed with GC-MS in the selective ion mode.

At 293 K and in artificial seawater, HLC (M atm^-1) was found to equal 574 +/- 201.

The HLC measurements of Gamma-HCH, which was used as reference substance, were in good agreement with literature values.

The Henry Law constant for t-OP is relatively high, indicating that significant deposition of t-OP from the atmosphere to surface waters can take place.

Reference 2

Endpoint:

Henry's law constant

Type of information:

calculation (if not (Q)SAR)

Remarks:

Migrated phrase: estimated by calculation

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: UK Environmental Risk Evaluation Report (ERAR) 2005 on 4-tert-octylphenol: assumed to be reliable information source

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

UK Environmental Risk Evaluation Report (ERAR) 2005: calculation of the HLC from the vapour pressure, molecular weight and water solubility of the substance.

GLP compliance:

not specified

H:

2.3 Pa m³/mol

Remarks on result:

other: value based on calculation from the vapour pressure, molecular weight and water solubility of the substance

H:

>= 0.46 - <= 0.7 Pa m³/mol

Remarks on result:

other: predicted with the HENRY program in EPISUITE (2004)

Conclusions:

An average HLC value of 0.58 Pa m³/mol was predicted with the HENRY program in EPISUITE (2004).

The calculated HLC from the vapour pressure of 0.21 Pa, a molecular weight of 206.33 g/mol and a water solubility of 19 mg/L results in a HLC for 4-tert-octylphenol of 2.3 Pa m³/mol.

Executive summary:

The UK ERA 2005 provides information on HLC values predicted with the HENRY program in EPISUITE (2004). HLC values of 0.46 and 0.70 Pa m³/mol, with the average being 0.58 Pa m³/mol, were calculated.

Moreover, the UK ERA provides information on the calculation of the HLC from the vapour pressure, molecular weight and water solubility of the substance. A vapour pressure of 0.21 Pa, a molecular weight of 206.33 g/mol and a water solubility of 19 mg/L were used, giving a HLC for 4-tert-octylphenol of 2.3 Pa m³/mol.

Description of key information

In a study conducted by Xie et al. (2004), which is also referenced in the UK Environmental Risk Evaluation Report for 4-tert-Octylphenol 2005 (UK ERA 2005), the  Henry’s Law Constants (HLC) was determined for tertiary octylphenol (t-OP) at concentrations of 0.08-0.10 mg/l, and Gamma-hexachlorocyclohexane (Gamma-HCH, reference substance) in artificial seawater over a temperature range 278–298 K using a dynamic equilibrium system. 

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):

0.52

at the temperature of:

298 K

Additional information

 

The HLC in artificial seawater determined by Xie et al. (2004) was 195 +/- 68 at 298 K which corresponds to 0.52 m³ Pa/mol.

In addition, the UK ERA 2005 provides information on HLC values predicted with the HENRY program in EPISUITE (2004). HLC values of 0.46 and 0.70 Pa m³/mol, with the average being 0.58 Pa m³/mol, were calculated.

The measured value of Xie et al. (2004) is in very good agreement with the predicted value using the HENRY program in EPISUITE (2004).

Moreover, the UK ERA provides information on the calculation of the HLC from the vapour pressure, molecular weight and water solubility of the substance. A vapour pressure of 0.21 Pa, a molecular weight of 206.33 g/mol and a water solubility of 19 mg/L were used, giving a HLC for 4-tert-octylphenol of 2.3 Pa m³/mol.

As the solubility of 4 -tert-octylphenol may be different in seawater, the measurement of the water-air partition coefficient in seawater may not be directly applicable to freshwater. In general terms the solubility of an organic compound would typically be lower in salt water (so the HLC would be higher). Ionisation of the phenol group could lead to increased solubility, but the pH of salt water is not high enough for significant ionisation of the substance to take place (pKa of 4 -tert-Octylphenol: 9.9, see Section 1.3.9.3 of UK ERA 2005). The measured value is in very good agreement with that predicted using the Henry program. Therefore the measured value for the HLC is recommended to be used in the assessment (0.52 Pa m³ /mol at 25°C).

In can be concluded from the Henry Law constant (HLC) that significant deposition of t-OP from the atmosphere to surface waters can take place.