Registration Dossier
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EC number: 939-511-7 | CAS number: 1064698-37-8
Phototransformation in air
Administrative data
Link to relevant study record(s)
Description of key information
PTBA has an estimated lifetime of 150-300 years by direct photolysis.
Key value for chemical safety assessment
Additional information
PTBA is expected to reside in the atmosphere. Given its uses, any releases will be solely to the atmospheric compartment. No releases to aquatic or terrestrial compartments are expected. Due to its vapor pressure and water solubility, this substance will not partition from the atmosphere to other compartments. Therefore, phototransformation processes will control its fate. PTBA was subject to direct photolysis under medium pressure mercury lamp irradiation. No additional phototransformation due to indirect photolysis by hydroxyl radical and O(¹D) (singlet oxygen atoms) could be detected above and beyond that due to direct photolysis, and it is assumed that direct photolysis is the dominant atmospheric fate of this substance. The atmospheric lifetime (150 to 300 years) of PTBA was estimated by comparison with the reference compound dichlorodifluoromethane (CAS# 75-71-8). Under experimental conditions, direct photolysis of CF2Cl2 and PTBA led to similar amounts of degradation. Atmospheric lifetime for PTBA is roughly equivalent to that of CF2Cl2, or ca. 150-300 years (DT50 = lifetime * 0.693). No stable degradation products expected once photoinitiation occurs (1). Ultimate degradation products are CO2, HF and NOx compounds.
1) C.J. Young, M.D. Hurley, T.J. Wallington, S. A. Mabury, 2006. Atmospheric lifetime and Global Warming Potential of a perfluoropolyether. Environ. Sci. Technol. Vol 40, pp. 2242-2246.
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