COMPARISON BETWEEN THE GAS-PHASE AND THE SOLUTION REACTION OF THE NITRATE RADICAL AND METHYLARENES

The reaction between the nitrate radical and methylarenes has been stu died in the gas phase. Benzaldehydes, benzyl nitrates, benzylic alcoho ls, and nitro derivatives have been found as reaction products. The re action of an intermediate alkoxy radical with oxygen or nitrogen dioxi de is suggested as the source of aldehydes and nitrates. The formation of nitro derivatives in the gas-phase reaction is of relevance to the environment. Kinetic isotope effect measurements favor the hypothesis of H-atom abstraction as the rate-determining step. The reaction of m ethylarenes with photogenerated nitrate radical in solution gives the same reaction products, but the reaction seems to occur via a rate-det ermining electron-transfer step, involving a radical cation in the tra nsition state.