Spin trapping with thiocarbonyl compounds

Abstract

A wide variety of radicals has been added to three relatively stable thiocarbonyl compounds, namely thiobenzoyltriphenylsilane (TBTPS), 2,4,6-tri-t-butylthiobenzaldehyde (TBTBA), and tris(trimethylsilyl)ethan-ethial or trisylthioaldehyde (TSTA), in order to test their ability to act as radical scavengers and the possibility of using them as spin-trapping agents. Reactions with radicals centred at elements from Groups IV to VI afforded in all cases persistent spin adducts which were studied by e.s.r. spectroscopy. In particular the adducts with TBTPS showed well resolved e.s.r. spectra for which the hyperfine pattern allowed in most cases an unambiguous identification of the trapped radical. The decay of some of the TBTA and TSTA adducts has been monitored, and the rate constants for the process determined. The rate of addition of the t-butoxyl and pivaloyl radicals to TSTA were also measured as (1.2 ± 0.5)× 10⁷ and (1.9 ± 0.5)× 10⁶ dm³ mol^–1 s^–1, respectively.