Trifluoromethane

Phototransformation in air

Administrative data

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

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Atmospheric processes. Wet and dry deposition of organic compounds are controlled by their vapor-particle partitioning.

Author:

Bidleman TF

Year:

1988

Bibliographic source:

Environ. Sci. Technol. 22:361-367 (cited in National Library of Medicine. Hazardous Substances Data Bank, HSDB/5207, accessed January 18, 2006).

Reference 2

Reference Type:

publication

Title:

Physical and Thermodynamic Properties of Pure Chemicals: Data Compilation.

Author:

Daubert TE and Danner RP

Year:

1995

Bibliographic source:

Design Inst. Phys. Prop. Data, Vol. 1, Amer. Inst. Chem. Eng., Hemisphere Pub. Corp., New York, NY (cited in National Library of Medicine. Hazardous Substances Data Bank, HSDB/5207, accessed January 18, 2006).

Reference 3

Reference Type:

publication

Title:

No information

Author:

Syracuse Research Corporation

Year:

2006

Bibliographic source:

cited in National Library of Medicine. Hazardous Substances Data Bank, HSDB/5207, accessed January 18, 2006.

Reference 4

Reference Type:

publication

Title:

Kinetics and mechanisms of the gas-phase reactions of the hydroxyl radical with organic compounds.

Author:

Atkinson R

Year:

1989

Bibliographic source:

J. Phys. Chem. Ref. Data. Monograph No.1. p 73 (cited in National Library of Medicine. Hazardous Substances Data Bank, HSDB/5207, accessed January 18, 2006).

Reference 5

Reference Type:

publication

Title:

No information

Author:

Dilling WL

Year:

1982

Bibliographic source:

in Conway RA, Environmental Risk Analysis for Chemicals, pp. 154-97 Van Nostrand Reinhold Co., NewYork, NY (cited in National Library of Medicine. Hazardous Substances Data Bank, HSDB/5207, accessed January 18, 2006).

Materials and methods

Principles of method if other than guideline:

Accepted calculation method

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Trifluoromethane

EC Number:

200-872-4

EC Name:

Trifluoromethane

Cas Number:

75-46-7

Molecular formula:

CHF3

IUPAC Name:

trifluoromethane

Details on test material:

- Purity: not reported

Study design

Estimation method (if used):

A model of gas/particle partitioning of semivolatile organic compounds in the atmosphere was used.

Results and discussion

Test performance:

The rate constant for the vapor-phase reaction of HFC-23 with photochemically-produced hydroxyl radicals has been measured as 2.4X10E-16 cm³/molecule-sec at 25°C (SRC, n.d.) using a structure estimation method.

Degradation rate constant

Reaction with:

OH radicals

Rate constant:

0 cm³ molecule-1 s-1

Any other information on results incl. tables

According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere (Bidleman, 1988), HFC-23, which has a vapor pressure of 3.53X10E+4 mm Hg at 25°C (Daubert and Danner, 1995), is expected to exist solely as a vapor in the ambient atmosphere. The rate constant for the vapor-phase reaction of HFC-23 with photochemically-produced hydroxyl radicals has been measured as 2.4X10E-16 cm³/molecule-sec at 25°C (SRC, n.d.) using a structure estimation method (Atkinson, 1989; SRC, n.d.). This corresponds to an atmospheric half-life of about 180 years at an atmospheric concentration of 5X10E+5 hydroxyl radicals per cm³ (Atkinson, 1989; SRC, n.d.). This relatively slow half-life in the lower atmosphere suggests that some HFC-23 may gradually diffuse into the stratosphere (SRC, n.d.). The diffusion half-life for transport from the troposphere to the stratosphere is on the order of 20 years (Dilling, 1982).

Applicant's summary and conclusion

Conclusions:

The atmospheric lifetime of the test substance with respect to *OH is 180 years.

This study and the conclusions which are drawn from it fulfill the quality criteria (validity, reliability, repeatability).

Executive summary:

According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere, the test substance, which has a vapor pressure of 3.53X10E+4 mm Hg at 25°C, is expected to exist solely as a vapor in the ambient atmosphere.The rate constant for the vapor-phase reaction of the test substance with photochemically-produced hydroxyl radicals has been measured as 2.4X10E-16 cm³/molecule-sec at 25°C using a structure estimation method. This corresponds to anatmospheric half-life of about 180 years at an atmospheric concentration of 5X10E+5 hydroxyl radicals per cm³. This relatively slow half-life in the lower atmosphere suggests that some test substance may gradually diffuse into the stratosphere. The diffusion half-life for transport from the troposphere to the stratosphere is on the order of 20 years.