Ionic Lewis Superacids in the Gas Phase. Part 4. CF3+ Initiated Ion-Molecule Reaction Patterns in the gamma-Radiolysis of CF4/n-Bases Gaseous Mixtures

A study of the gas-phase reactions between n-type nucleophiles (alcohols and amines) and the CF3+ ion, radiolytically (Co-60 gamma-rays) generated from CF4, is reported. Experiments have been carried out at 600-700 Torr total pressure, under conditions where radical routes to the products can be safely excluded. The major products from attack of CF3+ on the selected nucleophiles are the corresponding carbonyl derivatives. Thus, low yields of carbonates are recovered from alcohols, while ureas are produced in abundant yields from secondary amines. No products are obtained from a tertiary amine, as N-methylpiperidine. In alcohol/secondary amine mixtures, the corresponding carbamate accompanies formation of the carbonate and the urea. In alcohol/tertiary amine mixtures, only the carbonate and the carbamate are recovered. The mechanism of defluorination of the CF3 moiety after attack of CF3+ on the nucleophile is discussed and compared with the behavior of CF3+ toward the same nucleophiles, as observed under low-pressure (about 10(-6) Torr) Fourier-transform ion cyclotron resonance conditions, and predicted by ab initio MO calculations