DEAMINATION OF 2-METHYL-2-PROPANAMINE INDUCED BY HYDROXYL RADICALS AND METAL-IONS - A COMPARISON BETWEEN THE RATES OF BETA-ELIMINATION OF AMMONIA AND WATER

The reactions of .CH2C(CH3)2NH3+ with Cu+(aq) and Cr(H2O)6(2+) were studied using the pulse radiolysis technique. The formation of the unstable [Cu(II)-CH2C(CH3)2(NH3+)]+ and [(H2O)5Cr(III)-CH2C(CH3)2(NH3+)]2+ ions was observed in these reactions. These complexes decompose via beta-elimination of NH3 to yield 2-methylpropene, ammonia, and Cu2+(aq) or Cr3+(aq). The rates of these beta-elimination reactions are considerably slower than those of the analogous beta-hydroxyl elimination. It is suggested that the rates of the beta-elimination processes are correlated to the strengths of the C-O and C-N bonds, which are cleaved in these reactions. A valence-bond analysis coupled with some ab-initio SCF-MO computations explains the effect of protonation on these bond strengths.