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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:
weight of evidence
Study period:
2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Half-life in air estimated using the EPIsuite QSAR
Justification for type of information:
QSAR prediction
Guideline:
other:
Principles of method if other than guideline:
The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals. It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half-lives for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone.
GLP compliance:
no
Reaction with:
OH radicals
Rate constant:
0 cm³ molecule-1 s-1
Remarks on result:
other: C18: equals half-life of 6.123 hours
Reaction with:
OH radicals
Rate constant:
115.9 cm³ molecule-1 s-1
Remarks on result:
other: C18=: Equals half-flife of 3.32 hours

AOP Program (v1.92) Results:

===========================

SMILES : CCCCCCCCCCCCCCCCCCN(CCO)(CCO)(=O)

CHEM   : C18 alkyl bis(2-hydroxyethyl) amine oxide

MOL FOR: C22 H47 N1 O3

MOL WT : 373.63

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

Hydrogen Abstraction       =  62.6056 E-12 cm3/molecule-sec

**Reaction with N, S and -OH =   0.2800 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 =  62.8856 E-12 cm3/molecule-sec

  HALF-LIFE =     0.510 Days (12-hr day; 0.5E6 OH/cm3)

  HALF-LIFE =     6.123 Hrs

AOP Program (v1.92) Results:

===========================

SMILES : CCCCCCCCC=CCCCCCCCCN(CCO)(CCO)(=O)

CHEM   : C18= alkyl bis(2-hydroxyethyl) amine oxide

MOL FOR: C22 H45 N1 O3

MOL WT : 371.61

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

Hydrogen Abstraction       =  59.2511 E-12 cm3/molecule-sec

**Reaction with N, S and -OH =   0.2800 E-12 cm3/molecule-sec

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

Addition to Olefinic Bonds =  56.4000 E-12 cm3/molecule-sec [Cis-isomer]

Addition to Olefinic Bonds =  64.0000 E-12 cm3/molecule-sec [Trans-isomer]

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 = 115.9311 E-12 cm3/molecule-sec [Cis-isomer]

  OVERALL OH Rate Constant = 123.5311 E-12 cm3/molecule-sec [Trans-isomer]

  HALF-LIFE =    3.321 Hrs (12-hr day; 0.5E6 OH/cm3) [Cis-isomer]

  HALF-LIFE =    3.117 Hrs (12-hr day; 0.5E6 OH/cm3) [Trans-isomer]

........................  ** Designates Estimation(s) Using ASSUMED Value(s)

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

  OVERALL OZONE Rate Constant =  13.000000 E-17 cm3/molecule-sec [Cis-]

  OVERALL OZONE Rate Constant =  20.000000 E-17 cm3/molecule-sec [Trans-]

  HALF-LIFE =  2.116 Hrs (at 7E11 mol/cm3) [Cis-isomer]

  HALF-LIFE =  1.375 Hrs (at 7E11 mol/cm3) [Trans-isomer]

Conclusions:
In the atmosphere C16-18 (evennumbered, C18 unsaturated) alkyl bis(2-hydroxyethyl) amine oxide is likely to be degraded by reaction with hydroxyl radicals. The half-life in air is calculated using the EPIsuite QSAR using the advised 500000 OH-radicals/cm3 to be 6.12h for the C18 and 3.32 hours for the C18= constituent.
Executive summary:

In the atmosphere C16-18 (evennumbered, C18 unsaturated) alkyl bis(2-hydroxyethyl) amine oxide is likely to be degraded by reaction with hydroxyl radicals. Degradation rates for some components were calculated with the Atmospheric Oxidation Programme based on structure activity relationships developed by Atkinson (1987). With a concentration of 500,000 OH-radicals/cm3, degradation half-lives of 6.12 h for the octadecyl derivative and 3.32 h for the cis-isomer of the oleyl derivative were calculated. For the exposure calculations, the worst-case of 6.12 h can be used. Because there are no important releases into the atmosphere and volatilisation is expected to be negligible, this removal mechanism is thought to be of low relevance.

Description of key information

Degradation rate constants and half-lifes have been calculated with AOP for C16-18 (evennumbered, C18 unsaturated) alkyl bis(2-hydroxyethyl) amine oxide. The half-life as calculated for the C18 derivative of 6.12 h can be used for risk assessment.  

Key value for chemical safety assessment

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

Additional information

In the atmosphere C16-18 (evennumbered, C18 unsaturated) alkyl bis(2-hydroxyethyl) amine oxideis likely to be degraded by reaction with hydroxyl radicals. Degradation rates for some components were calculated with the Atmospheric Oxidation Programme based on structure activity relationships developed by Atkinson (1987). With a concentration of 500,000 OH-radicals/cm3, degradation half-lives of 6.12 h for the octadecyl derivative and 3.32 h for the cis-isomer of the oleyl derivative were calculated. For the exposure calculations, the worst-case of 6.12 h can be used. Because there are no important releases into the atmosphere and volatilisation is expected to be negligible, this removal mechanism is thought to be of low relevance.

Direct photolysis of alkyl-1,3-diaminopropanes in air will not occur, because it does not absorb UV radiation above 290 nm .Photo transformation in air is therefore assumed to be negligible.