Potassium trifluoroacetate

Phototransformation in water

Administrative data

Endpoint:

phototransformation in water

Type of information:

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

Adequacy of study:

key study

Study period:

Not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study not performed according to international guideline nor under GLP. The methodology is scientifically acceptable and the report is sufficiently well documented.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1995

Materials and methods

Study type:

indirect photolysis

Principles of method if other than guideline:

This study invastigated the reaction between haloacetates (including TFANa) and the most likely strong one electron oxidants to be able to react in atmospheric droplets: the radicals Cl2-, SO4- and OH. Rate constants for the reactions of the radicals with haloacetates were measured by laser-flash photolysis. Decay or formation curves observed subsequent to the flash were average before undergoing least-square analysis to obtain the first order rate constants.All the chemicals used were the purest grade available and all the experiment were performed in aquous medium with water purified.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium trifluoroacetate

EC Number:

220-879-6

EC Name:

Sodium trifluoroacetate

Cas Number:

2923-18-4

Molecular formula:

C2HF3O2.Na

IUPAC Name:

sodium trifluoroacetate

Details on test material:

- Name of test material (as cited in study report): Sodium salt of Trifluoroacetate (TFA)
- Molecular formula (if other than submission substance): CF3COO-
- Other: test material obtained from Aldrich and of the purest grade available.

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
See the endpoint study summary "Environmental fate and pathways" for the read-across justification.

Study design

Radiolabelling:

no

Sensitiser (for indirect photolysis)

Sensitiser (for indirect photolysis) 1

Type of sensitiser:

NO3 radical

Concentration of sensitiser:

other: 4 different substrates concentrations

Sensitiser (for indirect photolysis) 2

Type of sensitiser:

OH radical

Details on sensitiser:

Use of gamma radiolysis to produce OH (dose rate= 1.22 Gy.s-1 or 4.10 Gy.s-1)

Concentration of sensitiser:

other: 4 different substrates concentrations

Sensitiser (for indirect photolysis) 3

Type of sensitiser:

other: SO4-

Details on sensitiser:

produced by the 248 nm excimer laser-flash photolysis of sodium persulfate solution.

Concentration of sensitiser:

other: 4 different substrates concentrations

Sensitiser (for indirect photolysis) 4

Type of sensitiser:

other: Cl2-

Details on sensitiser:

produced by the reaction of SO4- with Cl-.

Concentration of sensitiser:

other: 4 different substrates concentrations

Results and discussion

Transformation products:

not measured

Any other information on results incl. tables

The relative reactivities of the haloacetates was determined to be :

CH2ClOO- (MCA) > CH2FCOO- (MFA) > CHCl2COO- (DCA) > CHF2COO- (DFA) > CCl3COO- (TCA) > CF3COO- (TFA).

Rate constants for some reactions of radicals with TFA in water in units of L.mol-1.s-1

3.9E+03 for NO3

1.6 +/- 0.1E+04 for SO4-

< 104 for Cl2-

<1E+06 for OH

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Conclusions:

TFA shows a low relative reactivity at the photolysis in aqueous solution.

Executive summary:

The kinetics of the acqueous-phase reactions of the free radicals OH, Cl2- and SO4- with the halogenated acetates, CH2FCOO- (MFA), CHF2COO- (DFA), CF3COO- (TFA) and with CH2ClOO- (MCA), CHCl2COO- (DCA), CCl3COO- (TCA) were investigated. Generally, the reactivity decreases with increasing halogen substitution and is in the order k(OH) > k(SO4 -) > k(Cl2 -), but there is no general relation between the effect on reactivity of chlorine and fluorine substitution.

Rate constants for some reactions of radicals with TFA in water in units of L.mol-1.s-1 were 3.9E+03 for NO3; 1.6 +/- 0.1E+04 for SO4 -; < 104 for Cl2- and <1E+06 for OH. TFA shows a low relative reactivity at the photolysis in aqueous solution.