diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

Phototransformation in air

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

phototransformation in air

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Principles of method if other than guideline:

SRC AOPWIN (v 1.91)

GLP compliance:

no

Estimation method (if used):

PHOTOCHEMICAL REACTION WITH OH RADICALS
- Concentration of OH radicals: 1.5 × 10+6
- Degradation rate constant: 5.4535 × 10-12
- Computer programme: SRC AOPWIN 1.91
- Other: calculated for 12 h- day

DT50:

1.96 d

Test condition:

12h day

DT50:

23.5 h

Test condition:

12 h day

SMILES : c2cc(CL)cc(CL)c2N1N=C(C(=O)OCC)CC1(C)C(=O)OCC

CHEM :

MOL FOR: C16 H18 CL2 N2 O4

MOL WT : 373.24

------------------- SUMMARY (AOP v1.91): HYDROXYL RADICALS -------------------

Hydrogen Abstraction = 4.3950 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 = 1.0585 E-12 cm3/molecule-sec

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

OVERALL OH Rate Constant = 5.4535 E-12 cm3/molecule-sec

HALF-LIFE = 1.961 Days (12-hr day; 1.5E6 OH/cm3)

HALF-LIFE = 23.536 Hrs

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

------------------- SUMMARY (AOP v1.91): OZONE REACTION ----------------------

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

(ONLY Olefins and Acetylenes are Estimated)

Experimental Database: NO Structure Matches

Reference 2

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:

accepted calculation method

Qualifier:

no guideline required

Principles of method if other than guideline:

Following the Atkinson approach, the photochemical half-life of mefenpyr-diethyl in air was estimated by calculation with the software Atmospheric Oxidation Program (AOPWIN). The updated version 1.88 was used with updated values for fragments and reactions

GLP compliance:

no

Estimation method (if used):

PHOTOCHEMICAL REACTION WITH OH RADICALS
- Concentration of OH radicals: 0.5E+06 radicals/cm³ (EU), 1.5E+06 radicals/cm² (USA)
- Degradation rate constant: 5.4535E-12
- Temperature for which rate constant was calculated: not given
- Computer programme: Following the Atkinson approach, the photochemical half-life of mefenpyr-diethyl in air was estimated by calculation with the software Atmospheric Oxidation Program (AOPWIN). The updated version 1.88 was used with updated values for fragments and reactions

DT50:

70.6 h

Test condition:

time frame: 24 h/d, OH concentration: 0.5E+06 radicals/cm³

Remarks on result:

other: EU

DT50:

23.5 h

Test condition:

time frame: 12 h/d, OH concentration: 1.5E+06 radicals/cm³

Remarks on result:

other: USA

Findings:

For a given concentration and an overall rate constant for the hydroxyl radicals the photolytic half life of AE F107892 in the atmosphere was calculated.

 

 Results of calculations according to the Atkinson approach for mefenpyr-diethyl using AOPWIN:

Scenario used	EU	USA
OH concentration [10^6radicals/cm³]	0.5	1.5
Time frame [hours/day]	24	12
OH rate constant [cm³ molecule^-1sec^-1]	5.4535 x 10^-12
Half life [hours]	70.6	23.5
Half life [days]	2.9	2.0

 

 

Conclusion:

The parent compound is rapidly degraded in air. In view of its low vapour pressure (6.3 x 10^-6Pa at 20°C) and by taking into account the rapid elimination observed in environmental fate tests there is no potential for a volatilisation and a long range transport in the atmosphere.

 

Description of key information

A half-life of 1.96 days was estimated for the substance. 

Key value for chemical safety assessment

Half-life in air:

23.5 h

Additional information

The photochemical half-life of the substance in air was estimated by calculation following the Atkinson approach with the software Atmospheric Oxidation Program (AOPWIN, version 1.91; 2010). The photolytic transformation process was calculated for a 12 h day and a concentration of 1.5E+06 OH radicals. The degradation rate constant was 5.454E-12 cm³/molecule*s. A half-life of 1.96 days was estimated for the substance (23.5 h). Therefore, a rapid degradation of the substance by photolytically induced processes is assumed.

The results are supported by a second calculation using the AOPWIN program (version 1.88; 1999). A half-life of 23.5 h was calculated for a OH radicals concentration of 1.5E+06 radicals/cm³ and a time frame of 12 h/day. The calculated half-life for a concentration of 0.5E+06 OH radicals/cm³ and a 24 hour day was 70.6 hours.