Methyl chloride anion, electron transfer from

The reaction of an organic halide with a metal is an oxidation-reduction in which the metal is the reducing agent. As shown in the fohowing equahons for the reactions of methyl chloride with lithium and with magnesium, a single-electron transfer from the metal converts methyl chloride to a radical anion, which then dissociates to a methyl radical and chloride ion. Bond formahon between methyl radical and a metal species ( Li or Mg" ) follows. 

Romanian scientists compared one-electron transfer reactions from triphenylmethyl or 2-methyl benzoyl chloride to nitrobenzene in thermal (210°C) conditions and on ultrasonic stimulation at 50°C (lancu et al. 1992, Vinatoru et al. 1994, Chivu et al. 2006). In the first step, the chloride cation-radical and the nitrobenzene anion-radicals are formed. In the thermal and acoustic variants, the reactions lead to the same set of products with one important exception The thermal reaction results in the formation of HCl, whereas ultrasonic stimulation results in CI2 evolution. At present, it is difficult to elucidate the mechanisms behind these two reactions. As an important conclusion, the sonochemical process goes through the inner-sphere electron transfer. The outer-sphere electron transfer mechanism is operative in the thermally induced process. 

Since the reaction of the formaldehyde radical anion with methyl chloride involves overcoming a barrier over time scales much larger than a picosecond, Yamataka et al. (1999) could not directly simulate the entire reaction process. Instead, they started at a transition-state structure, known from static quantum mechanical calculations chose random initial velocities and performed nine simulations at 298 K. Tliree of these simulations resulted in the formation of the reactants, three resulted in the formation of products via an electron-transfer reaction, and three resulted in the formation of products via a carbon-substituted Sn2 reaction. These three sets of resulting structures are shown in Fig. 4. 

---