Tin bis(2-ethylhexanoate)

Phototransformation in air

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in air

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Accepted calculation/estimation method, as recommended in ECHA Chapter 7 guidance (May 2008).

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Principles of method if other than guideline:

The second-order rate constant for reaction with photochemically-generated hydroxyl radical (indirect photolysis) was estimated using U.S. EPA AOPWIN software v1.92a (June 2008). The associated atmospheric half-life was calculated from an assumed average hydroxyl radical concentration of 500,000 molecules/cm3 and 24 hr. day (ECHA recommended values).

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

Estimation method (if used):

U.S. EPA AOPWIN software v1.92a (June 2008).
Assumed hydroxyl radical concentration of 500,000 molecules/cm3 and 24 hr photoday

Light source:

other: sunlight irradiance producing default tropospheric hydroxyl radical concentration of 500,000 molecules/cm3

Details on light source:

not applicable

Details on test conditions:

Half-lives calculated from estimated second-order rate constant, default hydroxyl radical concentration of 500,000 molecules/cm3, and 24-hr. photoday.

Preliminary study:

not applicable

Test performance:

not applicable

DT50:

1.6 d

Test condition:

Estimated half-life for reaction with hydroxyl radical (500,000 OH molecules/cm3) over 24 hr photoday

Transformation products:

not measured

Results with reference substance:

Butyric acid (CASRN 107-92-6)
SMILES: O=C(O)CCC
Experimental Rate Constant: 2.4 x 10-12 cm3/molecule*sec
Half-life based on experimental rate constant: 160 hrs (6.7 days)
Predicted Rate Constant: 2.7 x 10-12 cm3/molecule*sec
Half-life based on predicted rate constant: 142 hrs (5.9 days)

The prediction is accurate within a factor of 2 for estimating second-order rate constant of OH radical and organic acids such as butyric acid and 2-ethyl hexanoic acid

The predicted second-order rate constant for reaction of OH radical with Stannous Octoate is 9.9 x 10 -12 cm³/molecule*sec. This rate constant equates to an estimated half-life of 38.9 hrs, or 1.6 days; assuming an OH radical concentration of 500,000 molecules/cm³.

Validity criteria fulfilled:

not applicable

Conclusions:

The estimated atmospheric half-life for Stannous Octoate is 1.6 days, indicating that the substance will not behave as a persistent atmospheric pollutant if emitted to the air. This half-life is < 2 days, and therefore the substance is not regarded as having potential for long-range transport in the atmosphere.

Description of key information

The predicted second-order rate constant for reaction of OH radical with tin bis(2-ethylhexanoate) is 9.9 x 10^-12 cm³/molecule*sec. This rate constant equates to an estimated half-life of 38.9 hrs, or 1.6 days; assuming an OH radical concentration of 500,000 molecules/cm³.

Key value for chemical safety assessment

Half-life in air:

38.9 h

Degradation rate constant with OH radicals:

0 cm³ molecule-1 s-1

Additional information

The estimated atmospheric half-life for tin bis (2-ethylhexanoate) is 1.6 days, indicating that the substance will not behave as a persistent atmospheric pollutant if emitted to the air. This half-life is < 2 days, and therefore the substance is not regarded as having potential for long-range transport in the atmosphere.

The training set used to develop the AOPWIN algorithm does not include other Sn(II) organometallic compounds. However, since the mode of reactivity for the tin bis (2-ethylhexanoate) molecule with hydroxyl radical is dominated by reactions with the 2-ethyl hexanoate part (i.e., hydrogen abstraction), the presence of the Sn atom is not expected to result in decreased accuracy of the prediction. The accuracy of this prediction of the second-order rate constant for organic acids was demonstrated by comparing experimental and predicted rate constants for butyric acid. The predicted value deviates from the experimental value by only 12 %.