Structural effects on the beta-scission reaction of alkoxyl radicals. Direct measurement of the absolute rate constants for ring opening of benzocycloalken-1-oxyl radicals.
[reaction: see text] The absolute rate constants for beta-scission of a series of benzocycloalken-1-oxyl radicals and of the 2-(4-methylphenyl)-2-butoxyl radical have been measured directly by laser flash photolysis. The benzocycloalken-1-oxyl radicals undergo ring opening with rates which parallel the ring strain of the corresponding cycloalkanes. In the 1-X-indan-1-oxyl radical series, ring opening is observed when X = H, Me, whereas exclusive C-X bond cleavage occurs when X = Et. The factors governing the fragmentation regioselectivity are discussed.
Bietti
Massimo
M
Dipartimento di Scienze e Tecnologie Chimiche, Università Tor Vergata, Via della Ricerca Scientifica, 1 I-00133 Rome, Italy. bietti@uniroma2.it
Lanzalunga
Osvaldo
O
Salamone
Michela
M