Complications from dual roles of sodium hydride as a base and as a reducing agent

The dual ability of sodium hydride to behave as a base as well as a source of hydride, which could be applied as a common reagent for substrate activation in nucleophilic substitution reactions, is described. The structural nature of byproducts obtained from reaction of dimethylformamide or acetonitrile as solvents and benzyl bromide as an electrophile is also discussed.