LASER-FLASH PHOTOLYSIS OF NAPHTHYL DISELENIDES - REACTIVITIES OF NAPHTHYLSELENO RADICALS

Transient absorption spectra of 1-naphthylseleno (1-NaphSe(.)), and 2- naphthylseleno (2-NaphSe(.)) radicals, which are generated by laser-fl ash photolysis of the corresponding diselenides, were observed. The re actions of 1-NaphSe(.), and 2-NaphSe(.) with 2-methyl-1,3-butadiene an d alpha-methylstyrene were investigated by following the decay rates o f these seleno radicals. By both steady-state and laser-flash photolys is, it is proved that these seleno radicals add to alkenes in a revers ible manner. The reaction rate constants for such reversible addition reactions were determined by conducting the reaction in the presence o f O-2, which traps selectively the carbon-centered radicals formed by the addition reaction of the seleno radicals to the alkenes. The react ivity of 2-NaphSe(.) is higher than that of 1-NaphSe(.), both of which are less reactive than PhSe .. These reactivities were interpreted wi th the properties of SOMO calculated by MO method. (C) 1998 John Wiley & Sons, Inc.