DETECTION AND IDENTIFICATION OF SHORT-LIVED FREE RADICALS BY ELECTRON SPIN RESONANCE TRAPPING TECHNIQUES (SPIN TRAPPING) - PHOTOLYSIS OF ORGANOLEAD, -TIN, AND -MERCURY COMPOUNDS

A free-radical trapping technique is described which can be used to detect and identify reactive shortlived free radicals in reacting systems by obtaining the electron spin resonance spectrum of the radical addition product (a “spin adduct”) of phenyl-N-t-butylnitrone (a “spin trap”) (eq 6). The nitrogen and β-hydrogen hyperfine coupling constants of the spin adduct (an α-substituted benzyl-t-butylnitroxide) are a unique set of parameters for each reactive radical trapped. Verification for the structure of the spin adduct can be readily obtained for alkyl and aryl spin adducts by an addition reaction between the organolithium or Grignard compound of corresponding structure and phenyl-t-butylnitrone followed by oxygen oxidation. It has been shown that in the photolysis of organolead, -tin, and -mercury compounds the order of cleavage is phenyl > alkyl ° acetate or halide. Phenyl or n-butyl carbon-tin bond cleavage occurs more readily than tin-tin bond cleavage. Stable radicals, e.g., triphenylmethyl are not trapped. Very shortlived radicals, e.g., acetoxy, are trapped without difficulty. © 1969, American Chemical Society. All rights reserved.