Bromine and carbon isotope effects during photolysis of brominated phenols.
In the present study, carbon and bromine isotope effects during UV-photodegradation of bromophenols in aqueous and ethanolic solutions were determined. An anomalous relatively high inverse bromine isotope fractionation (εreactive position up to +5.1‰) along with normal carbon isotope effect (εreactive position of -12.6‰ to -23.4‰) observed in our study may be attributed to coexistence of both mass-dependent and mass-independent isotope fractionation of C-Br bond cleavage. Isotope effects of a similar scale were observed for all the studied reactions in ethanol, and for 4-bromophenol in aqueous solution. This may point out related radical mechanism for these processes. The lack of any carbon and bromine isotope effects during photodegradation of 2-bromophenol in aqueous solution possibly indicates that C-Br bond cleavage is not a rate-limiting step in the reaction. The bromine isotope fractionation, without any detectable carbon isotope effect, that was observed for 3-bromophenol photolysis in aqueous solution probably originates from mass-independent fractionation.
The Geological Survey of Israel , 30 Malkhei Israel St., Jerusalem 95501, Israel.
Yevgeni
Y
Zakon
Ludwik
L
Halicz
Faina
F
Gelman
D001966:Bromine / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry*; D005591:Chemical Fractionation; D002849:Chromatography, Gas; D004777:Environment; D000431:Ethanol / Q000737:chemistry; D054879:Halogenation; D007554:Isotopes / Q000737:chemistry; D007700:Kinetics; D010636:Phenols / Q000737:chemistry*; D010782:Photolysis; D012996:Solutions; D014867:Water / Q000737:chemistry
D002247:Carbon Isotopes; D007554:Isotopes; D010636:Phenols; D012996:Solutions; D014867:Water; D000431:Ethanol; C032038:2-bromophenol; C032037:4-bromophenol; D001966:Bromine; C040659:3-bromophenol