INTRAMOLECULAR SELECTIVITY OF MUONIUM TOWARDS CHLORINATED AROMATIC-COMPOUNDS

Muon resonance studies show that muonium atoms (Mu) in ethanol add sel ectively to certain C-sites of aromatic compounds containing -Cl and - OH substituents. The sites chosen seem to be those carrying the lowest electron density. This helps to characterize Mu as a nucleophile in a ddition reactions and, in this respect, Mu differs from ordinary H-ato ms. The study shows no apparent inter-molecular selectivity between a pair of aromatic solutes in an equimolar mixture, but strong intra-mol ecular selectivity in an ether composed of those two aromatic rings. T his difference between intra- and inter-molecular selectivity is inter preted as kinetic in origin - arising from the 'caging effect' of the solvent and peculiar to reactions close to the diffusion-controlled li mit.