The photochemical reaction of cerium(IV) ammonium nitrate (CAN) in acetonitrile with cyclohexene, 1-octene and a series of styrene derivatives leads to the formation of 1,2-dinitrate adducts in high yields. The reaction takes place by the intermediacy of the nitrate radical which forms in the photolysis of CAN. The reaction rate of NO3· with the olefinic substrates has been determined by the laser flash photolysis technique. High values of reactivity are observed, the second order rate constants ranging from 5×108 to 9×109 M-1s-1. The plot of the rate data for substituted styrenes against XXX+ values is linear and affords aXXX value of -0.97. It has also been found that the kinetic data fit in with the Rehm-Weller equation for electron transfer processes, thus suggesting that the transfer of an electron from the substrate to the attacking radical is the first (and rate determining) step in the reaction of styrene derivatives with NO3· This suggestion is also supported by the observation that View the MathML source-β-methylstyrene is more reactive than α-methylstyrene, in line with the easier oxidizability of the former substrate and in contrast with what is observed in free radical additions. Kinetic data for 1-octene and cyclohexene do not fit the Rehm-Weller plot and the mechanistic attribution to the reaction of these substrates with nitrate radical is uncertain.
The Photochemical Reaction of Cerium(IV) Animonium Nitrate with Alkenes. Rate and Mechanism for the Addition of the Nitrate Radical to Alkenes
SEBASTIANI, Giovanni Vittorio;DEL GIACCO, Tiziana;MURGIA, Sandro Maria
1988
Abstract
The photochemical reaction of cerium(IV) ammonium nitrate (CAN) in acetonitrile with cyclohexene, 1-octene and a series of styrene derivatives leads to the formation of 1,2-dinitrate adducts in high yields. The reaction takes place by the intermediacy of the nitrate radical which forms in the photolysis of CAN. The reaction rate of NO3· with the olefinic substrates has been determined by the laser flash photolysis technique. High values of reactivity are observed, the second order rate constants ranging from 5×108 to 9×109 M-1s-1. The plot of the rate data for substituted styrenes against XXX+ values is linear and affords aXXX value of -0.97. It has also been found that the kinetic data fit in with the Rehm-Weller equation for electron transfer processes, thus suggesting that the transfer of an electron from the substrate to the attacking radical is the first (and rate determining) step in the reaction of styrene derivatives with NO3· This suggestion is also supported by the observation that View the MathML source-β-methylstyrene is more reactive than α-methylstyrene, in line with the easier oxidizability of the former substrate and in contrast with what is observed in free radical additions. Kinetic data for 1-octene and cyclohexene do not fit the Rehm-Weller plot and the mechanistic attribution to the reaction of these substrates with nitrate radical is uncertain.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
