MECHANISM OF THE γ-RADIOLYSIS OF 2-PROPANOL SOLUTIONS OF CYCLOHEXANONES

Article abstract of DOI:10.1016/S0040-4020(01)82451-0

The γ-radiolysis of 2-propanol solutions of cyclohexanone gives mainly hydrogen, acetone, pinacol, methane derived from 2-propanol, and cyclohexanol, 2-(2-cyclohexanonyl)-cyclohexanone, and 3-(2-hydroxy-2-propyl)cyclohexanone derived from cyclohexanone.The radiolytic yields of all these products were highly dependent on the initial cyclohexanone concentration.The formation of cyclic alcohols by radioreduction has been extended to various substituted cyclohexanones.Radiolytically generated solvated electrons are scavenged by cyclohexanone, leading to the corresponding radical anions.The protonation of these radical anions gives rise to cyclohexanol via the dismutation of the hydroxycyclohexyl radicals.Steady state radiolysis measurements were complemented by pulse radiolysis in dilute solution.It was established that radical-anions and hydroxylated radicals decayed according to a second order rate law.When ketone concentration was lower than 0.1M, radiolytic yields were in agreement with the mechanism mentioned above.However, in concentrated media the large increase in G(cyclohexanol) cannot be only accounted for by the involvement of radiolytically generated solvated electrons; probably it is due to an electron transfer from the cyclohexanone enolate to cyclohexanone itself, thus generating extra amounts of cyclohexanone radical anions.