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EC number: 690-995-3 | CAS number: 756-12-7
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.
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.
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