Resolutions via Arsonium Ions

An optically active arsonium ion containing an allyl or a benzyl group is quantitatively reduced at a mercury electrode in water or ethanol with retention of configuration at arsenic (and liberation of toluene or propene) to give an optically active tertiary arsine, free of functional groups on the organic substituents (equation 3). 

In aqueous solution, determinations of half-wave potentials have indicated the following ordering of difficulty of removal of organic substituents from arsonium ions  

Cathodic cleavage of benzyl groups from resolved arsonium salts have been used to produce optically active tertiary arsines (Table 4). Some examples of interconversions 

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