Sodium ethanolate

Phototransformation in air

Administrative data

Endpoint:

phototransformation in air

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

1976

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

No detailed methodology available in this reference. Otherwise acceptable with sufficient documentation to show that it meets basic scientific principles and contains enough detail to be able to judge the results reliable as a contribution to the understanding of the environmental fate of this substance.

Data source

Reference

Reference Type:

publication

Title:

Rate constants for reactions ofhydroxyl radicals with alcohol vapours at 292 K.

Author:

Campbell, I.M. et al.

Year:

1976

Bibliographic source:

Chem. Phys.Letters 38, 362 - 364.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Basis of method is the chain mechanism taking place in H2O2/NO2/CO/substrate mixtures. Plotting [H2O2]/[CO2] versus [substrate]/[CO] gives a linear plot. Method assumes 1:1 stochiometry between [H2O2] and OH radical formation in the presence of excess NO2. From the gradient it is then possible to determine the rate constant for reaction with OH radicals.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Ethanol

EC Number:

200-578-6

EC Name:

Ethanol

Cas Number:

64-17-5

Molecular formula:

C2H6O

IUPAC Name:

ethanol

Details on test material:

Test substance: no data

Study design

Light source:

other: (no light source used in this system)

Details on test conditions:

Sensitiser (for indirect photolysis): OH (generated from reaction of N2O2+NO2->OH. + HNO2.
Initial H2O2 partial pressure 11Pa.
Initial NO2 partial pressure 130Pa
System pressure 13.3kPa

Duration of test at given test condition

Temp.:

19 °C

Results and discussion

Dissipation half-life of parent compound

DT50:

10 h

Test condition:

Typical urban sunlit atmosphere and calculated from measured rate constant for reaction with OH radicals

Transformation products:

not measured

Any other information on results incl. tables

A value for the half-life in a typical urban sunlit atmosphere was calculated from the rate constant for the reaction of the hydroxyl radical with ethanol vapour, assuming hydroxyl radical concentrations in such atmospheres to the order of 10E-14 mol.dm-3.

The calculated half-life was 10 hours. The rate constant was 1.8 +/- 0.2 x 10^-9 dm^3mol^-1s^-1

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Executive summary:

The rate constant for the reaction of ethanol with hydroxyl radicals was measured using a method that creates OH radicals through the reaction of hydrogen peroxide and nitrogen dioxide in the vapour phase and under dark conditions. Using this method, the rate constant was measured as 1.8E-9 dm3/(mol.sec) (+/-11%). From this value, the estimated half life in the atmosphere from reaction with hydroxy radicals is estimated at 10 hours.