Registration Dossier

Administrative data

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 Aug - 11 Oct 2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-guideline, non-GLP study. Scientifically sound principles, limited documentation, incomplete mass balance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2014

Materials and methods

Test guideline
Qualifier:
no guideline followed
Deviations:
not applicable
Principles of method if other than guideline:
Direct phototransformation rate using continuous-spectrum UV-Vis light source, acetaldehyde used as reference substance.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Pressurized liquid
Details on test material:
- Name of test material (as cited in study report): F-12714, L2108
- Substance type: Pure active substance
- Physical state: Pressurized liquid
- Analytical purity: 99.98%

Study design

Light source:
Xenon lamp
Details on light source:
Study used an Oriel model 6251 UV lamp with 75W Hg-Xe bulb and a filter attenuating wavelengths <285 nm. The Hg-Xe source provides an almost featureless spectrum in the UV and visible, with a blackbody temperature ca. 5500-6000 K (Fig. 1)
Details on test conditions:
Tests were done in a 5.7-L, heated FTIR gas cell with 10 meter path length at a temperature of ca. 25 °C and a pressure of ca. 14.3 psia (98 kPa). Pathlength was calibrated using a certified ethylene calibration standard. Irradiation was through a semiconductor-grade quartz window. Measurements were by Midac Corp. I-series FTIR with a scan range of 650-4500 cm‾¹ and a resolution of 0.5 cm‾¹. Gasses were admitted using mass flow controls through a manifold. The cell was sealed when concentration of gases reach the target value. Background spectra were obtained using 128 co-added scans, and sample spectra using 64 to 128 co-added scans. Before each run, the system was filled above ambient pressure and the pressure monitored to assess leaks; none were detected. Substance concentration in each sample at a given time was assessed in two ways. AutoQuantPro™ software uses a series of reference spectra for the compounds of interest and applies a classical least squared method to determine the fractional contribution of each reference spectrum to the sample spectrum. The proportion of the reference spectrum is then equal to the concentration in the sample, assuming a linear relationship between absorbance and concentration. Concentration was confirmed by manual subtraction of a reference spectrum from the sample spectrum. The fraction of the reference spectrum (subtraction factor) was used to calculate concentration using Conc (ppmv) = subtraction factor * reference substance concentration (ppmv*m)/cell path length (m).
Reference spectra and the region used for analysis were available for the following:
CAS# 756-12-7: Region #1: 1142.13 - 1238.89 cm‾¹; Region #2: 854.51 - 1013.15 cm‾¹
Trifluoroacetyl fluoride: 706.35 - 1299.05 cm‾¹
Trifluoroacetic acid: 1061.94 - 1304.83 cm‾¹
Carbonyl fluoride: 737.20 - 816.01 cm‾¹
Carbon monoxide: 2004.36 - 2261.52 cm‾¹
Carbon dioxide: 2273.75 - 2404.94 cm‾¹
Water: Region #1: 3380.43 - 3986.26 cm‾¹; Region #2: 1233.35 - 2078.33 cm‾¹
Acetaldehyde: 2600.50 - 2811.77 cm‾¹
Methanol: 948.86 - 1094.04 cm‾¹
Acetic acid: 1740.00 - 1834.63 cm‾¹
Formaldehyde: 2635.57 - 2841.45 cm‾¹
Formic acid: Region #1: 3410.11 - 2797.95 cm‾¹; Region #2: 1689.96 - 1808.04 cm‾¹

Lifetime experiments:
Experiments were conducted using variable concentrations of water vapor. Reaction mixtures consisted of CAS# 756-12-7, acetaldehyde, water vapor, and nitrogen as follows:
Hydrated run 1: 6.7 ppmv CAS# 756-12-7, 71 ppmv acetaldehyde, ca 500 ppmv water vapor, balance N2
Hydrated run 2: 7.9 ppmv CAS# 756-12-7, 52 ppmv acetaldehyde, ca 500 ppmv water vapor, balance N2
Dry run 1: 7.1 ppmv CAS# 756-12-7, 70 ppmv acetaldehyde, 37.5 ppmv water vapor, balance N2
Dry run 2: 6.6 ppmv CAS# 756-12-7, 69 ppmv acetaldehyde, 37.3 ppmv water vapor, balance N2
Concentrations were monitored a variable length of time (>5 min) with the lamp off to evaluate losses to the system. The lamp was then switched on and the reaction mixtures monitored until degradation rates became linear.

Degradation product identification:

2) A smaller amount of CAS# 756-12-7 was admitted to the chamber with minimum moisture and no acetaldehyde, balance nitrogen, and irradiated 450 minutes.
Solo run 1: 1.0 ppmv CAS# 756-12-7, no acetaldehyde, 2.2 ppmv water vapor, balance N2
Solo run 2: 1.4 ppmv CAS# 756-12-7, no acetaldehyde, 4.6 ppmv water vapor, balance N2
Degradation products were monitored by FTIR.
Duration of test at given test conditionopen allclose all
Duration:
200 min
Temp.:
25 °C
Initial conc. measured:
6.7 other: ppmv
Duration:
80 min
Temp.:
25 °C
Initial conc. measured:
7.9 other: ppmv
Duration:
120 min
Temp.:
25 °C
Initial conc. measured:
7.1 other: ppmv
Duration:
320 min
Temp.:
25 °C
Initial conc. measured:
6.6 other: ppmv
Reference substance:
yes
Remarks:
acetaldehyde

Results and discussion

Dissipation half-life of parent compound
DT50:
11 d
Test condition:
based on relative photolysis rate v. acetaldehyde and lifetime of acetaldehyde
Transformation products:
yes
Identity of transformation productsopen allclose all
No.:
#1
Reference
Reference substance name:
Unnamed
Inventory number:
InventoryMultipleMappingImpl [inventoryEntryValue=EC 206-558-3]
IUPAC name:
trifluoroacetyl fluoride
Identity:
Acetyl fluoride, trifluoro-
CAS number:
354-34-7
Molecular formula:
C2F4O
Molecular weight:
116.014
SMILES notation:
FC(=O)C(F)(F)F
InChl:
InChI=1/C2F4O/c3-1(7)2(4,5)6
No.:
#2
Reference
Reference substance name:
Unnamed
IUPAC name:
CARBONYL FLUORIDE
Identifier:
common name
Identity:
CARBONYL FLUORIDE

Any other information on results incl. tables

Four runs were done to assess atmospheric lifetime (See attachments 1 and 2). Logarithms of the ratios of concentration at time = i and time = zero (Ci/C0) were plotted as a function of time for both acetaldehyde and CAS# 756-12-7. R² for the regression equations was better than 0.9925 for all curves. The quotient of the two slopes was used to establish rate ratio, and the rate ratios multiplied by the atmospheric lifetime of acetaldehyde (5 days) to obtain the lifetime of CAS# 756-12-7.

Dry run 1, rate ratio 0.29, lifetime 17 days

Dry run 2, rate ratio 0.31, lifetime 16 days

Humidified run 1, rate ratio 0.31, lifetime 16 days

Humidified run 2, rate ratio 0.38, lifetime 13 days

The average lifetime was 16 ± 1.9 days (half-life, 11 days). Water vapor concentration during photolysis had little or no impact on phototransformation rate.

Degradation products of CAS# 756-12-7 were examined in nearly water-free atmosphere to simplify analysis of the spectra. Two degradation products were found, trifluoroacetyl fluoride and carbonyl fluoride (See attachment 3). Each was found in approximately 33% to 50% molar yield v. parent. Carbon dioxide and carbon monoxide were also detected in high amounts in the reaction chamber, however, the system releases these substances steadily upon closure of the chamber. No information was provided to assess rate of release, and the contribution of CAS# 756-12-7 photolysis to CO2 and CO production cannot be assessed. Carbon balance is incomplete in this experiment. HF was specifically examined but not found in reaction products. Spectral features that were not accounted for by reference spectra were absent, therefore hydrofluorocarbons or perfluorocarbons were not among the degradation products. Fluorine balance is also incomplete in this experiment.

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Conclusions:
The atmospheric lifetime of CAS# 756-12-7 by direct photolysis is 16 ± 1.9 days.
Executive summary:

The atmospheric fate of CAS# 756-12-7 was assessed using direct phototransformation under a 75W mercury-xenon lamp in a nitrogen atmosphere at ca. 25 °C and ca. 1 atmosphere pressure. Acetaldehyde was used as a reference compound. Water vapor concentration was held at two levels. No effect was seen of varying water vapor concentration. Lifetime was assessed by determining reaction rate ratio of CAS# 756-12-7 and acetaldehyde in each run, and multiplying by atmospheric lifetime of acetaldehyde (5 days). The atmospheric lifetime of CAS# 756-12-7 by direct photolysis is 16 ± 1.9 days. Transformation products identified in separate tests done in a nitrogen atmosphere without acetaldehyde and with minimal water vapor included carbonyl fluoride and trifluoroacetyl fluoride. A complete mass balance for carbon and fluorine could not be obtained.

The study was conducted using sound scientific principles, but has minimal documentation and was not conducted under GLP. Also, the mass balance for the reaction was incomplete. Therefore this study is deemed reliable with restrictions. It is suitable for Risk Assessment, Classification & Labeling, and PBT Analysis.