Von Richter Reaction
When aromatic nitro compounds are treated with potassium cyanide in aqueous ethanol to generate a carboxylic acid ortho to the existing nitro group is known as Victor Von Richter reaction or simply Von Richter reaction.
This reaction is cine substitution (the entering group takes up a position next (i.e. adjacent) to that occupied by the leaving group).
Best results are obtained when electron withdrawing group is present at ortho or para position. Reaction gives a small yeild of product.
The von Richter reaction can be inhibited in the presence of potassium ferricyanide (K3Fe(CN)6) and sodium sulfite.