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Environmental fate & pathways

Phototransformation in air

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Reference
Endpoint:
phototransformation in air
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Accepted calculation method
Qualifier:
no guideline followed
Principles of method if other than guideline:
The value was calculated using the Estimation Programs Interface (EPI) SuiteTM United States Environmental Protection Agency AOPWIN Program (v1.92). The estimation methods used by AOPWIN are based upon the structure-activity relationship (SAR) methods developed by Dr. Roger Atkinson and co-workers (Atkinson, 1985, 1986, 1987, 1991; Atkinson and Carter, 1984; Biermann et al, 1985; Kwok et al, 1992, Kwok and Atkinson, 1995; Kwok et al, 1996). AOPWIN incorporates updated fragment and reaction values as cited in Kwok and Atkinson (1995). In addition, Syracuse Research Corporation has derived some additional fragment and reaction values from more recent experimental data.
GLP compliance:
no
Estimation method (if used):
AOP based on SAR methods developed by Atkinson.
DT50:
ca. 5.274 h
Test condition:
For the substance DIPE. 1.5E6 OH/cm³, 25 °C
DT50:
ca. 0.439 d
Test condition:
For the substance DIPE. 1.5E6 OH/cm³, 25 °C, (12-hr day)
DT50:
ca. 4.001 h
Test condition:
For the substance DSBE. 1.5E6 OH/cm³, 25 °C
DT50:
ca. 0.333 d
Test condition:
For the substance DSBE. 1.5E6 OH/cm³, 25 °C, (12-hr day)

SMILES : CC(C)OC(C)C

CHEM : DIPE

MOL FOR: C6 H14 O1

MOL WT : 102.18

------------------- SUMMARY (AOP v1.92): HYDROXYL RADICALS (25 deg C) --------

Hydrogen Abstraction = 24.3371 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 = 24.3371 E-12 cm3/molecule-sec

HALF-LIFE = 0.439 Days (12-hr day; 1.5E6 OH/cm3)

HALF-LIFE = 5.274 Hrs

------------------- SUMMARY (AOP v1.91): OZONE REACTION (25 deg C) -----------

****** NO OZONE REACTION ESTIMATION ******

(ONLY Olefins and Acetylenes are Estimated)

Experimental Database Structure Match:

Chem Name : Diisopropyl ether

CAS Number: 000108-20-3

Exper OH rate constant : 10.2 E-12 cm3/molecule-sec

Exper OH Reference: KWOK,ESC & ATKINSON,R (1994)

Exper Ozone rate constant: --- cm3/molecule-sec

Exper NO3 rate constant : --- cm3/molecule-sec

-------------------------------------------------------------------------------------------------

SMILES : CCC(C)OC(C)CC

CHEM : DSBE

MOL FOR: C8 H18 O1

MOL WT : 130.23

------------------- SUMMARY (AOP v1.92): HYDROXYL RADICALS (25 deg C) --------

Hydrogen Abstraction = 32.0784 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 = 32.0784 E-12 cm3/molecule-sec

HALF-LIFE = 0.333 Days (12-hr day; 1.5E6 OH/cm3)

HALF-LIFE = 4.001 Hrs

------------------- SUMMARY (AOP v1.91): OZONE REACTION (25 deg C) -----------

****** NO OZONE REACTION ESTIMATION ******

(ONLY Olefins and Acetylenes are Estimated)

Experimental Database: NO Structure Matches

Validity criteria fulfilled:
not applicable
Remarks:
QSAR estimate
Conclusions:
T 1/2 (atmospheric oxidation) for di-isopropyl ether is 5.274 h and for di-isobutyl ether 4.001 h
Executive summary:

The atmospheric oxidation half-lives were calculated to be 5.274 h for DIPE and 4.001 h for DSBE (AOPWIN v1.92).

Description of key information

Phototransformation in air T1/2 = 5.274 hours or 0.439 days (12 hrs daylight) for DIPE and T1/2 = 4.001 hours or 0.333 days (12 hrs daylight) for DSBE at 298 K (sensitizer: OH radical) (AOP win v1.92).

Key value for chemical safety assessment

Half-life in air:
5.3 h

Additional information

A degradation rate constant with OH radicals of 24.3371 E-12 cm³ molecule-1 sec-1 at 25 °C and 1.5E6 OH/cm³ for DIPE and of 32.0784 E-12cm molecule-1 sec-1 at 25 °C and 1.5E6 OH/cm³ for DSBE was estimated using AOP win v1.92, based on SAR developed by Atkinson. Both DIPE and DSBE are expected to rapidly degrade in the atmosphere by hydroxyl radical attack.