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Environmental fate & pathways

Phototransformation in air

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Endpoint:
phototransformation in air
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
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:
QSAR prediction: Model considered valid by OECD
Qualifier:
no guideline required
Principles of method if other than guideline:
QSAR model, EPI Suite v 4.1/Aopwin v1.92
GLP compliance:
no
Remarks:
not applicable
Estimation method (if used):
PHOTOCHEMICAL REACTION WITH OH RADICALS - assumed reaction conditions used in model:
- Concentration of OH radicals:1.5E6 per cm3
- Temperature for which rate constant was calculated: 25C
- Computer programme: AOPWIN v1.92
Light source:
sunlight
Preliminary study:
Using the AOPWIN QSAR model, the photochemical degradation rate of Potassium amyl xanthate in the atmosphere is 13.7578 E-12 cm3/molecule-sec, with a resultant predicted half live of 9.329 Hrs ( 0.777 Days (12-hr day; 1.5E6 OH/cm3))
OVERALL OH Rate Constant = 13.7578 E-12 cm3/molecule-sec
HALF-LIFE = 0.777 Days (12-hr day; 1.5E6 OH/cm3)
HALF-LIFE = 9.329 Hrs
Reaction with:
OH radicals
Rate constant:
0 cm³ molecule-1 s-1
Transformation products:
no
Results with reference substance:
OVERALL OH Rate Constant = 13.7578 E-12 cm3/molecule-sec
HALF-LIFE = 0.777 Days (12-hr day; 1.5E6 OH/cm3)
HALF-LIFE = 9.329 Hrs

Hydrogen Abstraction      = 13.7578 E-12 cm3/molecule-sec

Reaction with N, S and -OH =  0.0000 E-12 cm3/molecule-sec

Addition to Triple Bonds  =  0.0000 E-12 cm3/molecule-sec

Addition to Olefinic Bonds =  0.0000 E-12 cm3/molecule-sec

Addition to Aromatic Rings =  0.0000 E-12 cm3/molecule-sec

Addition to Fused Rings   =  0.0000 E-12 cm3/molecule-sec

 

 OVERALL OH Rate Constant = 13.7578 E-12 cm3/molecule-sec

 HALF-LIFE =    0.777 Days (12-hr day; 1.5E6 OH/cm3)

 HALF-LIFE =    9.329 Hrs

Validity criteria fulfilled:
yes
Remarks:
The photochemical degradation rate of Potassiumethyl xanthate in the atmosphere is 6.1734 E-12 cm3/molecule-sec, with a resultant predicted half live of 20.791 Hrs ( 1.733 Days (12-hr day; 1.5E6 OH/cm3)
Conclusions:
Using the AOPWIN QSAR model, the photochemical degradation rate of Potassium amyl xanthate in the atmosphere is 13.7578 E-12 cm3/molecule-sec, with a resultant predicted half live of 9.329 Hrs ( 0.777 Days (12-hr day; 1.5E6 OH/cm3))
Executive summary:

Using the AOPWIN QSAR model, the photochemical degradation rate of Potassium amyl xanthate in the atmosphere is 13.7578 E-12 cm3/molecule-sec, with a resultant predicted half live of 9.329 Hrs ( 0.777 Days (12-hr day; 1.5E6 OH/cm3))

Endpoint:
phototransformation in air
Data waiving:
other justification
Justification for data waiving:
other:

Description of key information

Using the AOPWIN QSAR model, the photochemical degradation rate of Potassium amyl xanthate in the atmosphere is 13.7578 E-12  cm3/molecule-sec, with a resultant predicted half live of  9.329   Hrs ( 0.777 Days (12-hr day; 1.5E6 OH/cm3)).
If released to air, a vapor pressure of 0.000000000339 mm Hg  at 25 deg C (0.000000000339 mm Hg is  equivalent to  vapour pressure of  4.52E-008 Pa ) indicates that Potassium amyl xanthate will exist solely as a vapor in the atmosphere. Vapor-phase Potassium amyl xanthate will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 0.777 days, calculated from its rate constant of 13.7578 E-12 cm3/molecule-sec at 25 deg. 
Xanthates do not contain chromophores that absorb at wavelengths >290 nm and therefore Potassium amyl xanthate is not expected to be susceptible to direct photolysis by sunlight.

Key value for chemical safety assessment

Half-life in air:
0.777 d
Degradation rate constant with OH radicals:
0 cm³ molecule-1 s-1

Additional information

Using the AOPWIN QSAR model, the photochemical degradation rate of Potassium amyl xanthate in the atmosphere is 13.7578 E-12 cm3/molecule-sec, with a resultant predicted half live of 9.329  Hrs ( 0.777 Days (12-hr day; 1.5E6 OH/cm3)).

 

OVERALL OH Rate Constant = 13.7578 E-12 cm3/molecule-sec

 HALF-LIFE =    0.777 Days (12-hr day; 1.5E6 OH/cm3)

 HALF-LIFE =    9.329 Hrs

If released to air, a vapor pressure of 0.000000000339 mm Hg at 25 deg C (0.000000000339 mm Hg is equivalent to vapour pressure of 4.52E-008 Pa ) indicates that Potassium amyl xanthate will exist solely as a vapor in the atmosphere. Vapor-phase Potassium amyl xanthate will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 0.777 days, calculated from its rate constant of 13.7578 E-12 cm3/molecule-sec at 25 deg.

Xanthates do not contain chromophores that absorb at wavelengths >290 nm and therefore Potassium amyl xanthate is not expected to be susceptible to direct photolysis by sunlight.