User:Stolze Rose/Sandbox/Von-Richter-Reaction

The Von-Richter reaction, also named Von-Richter rearrangement, is a name reaction in the organic chemistry. It is named after Victor von Richter, who discovered this reaction in year 1871. It is the chemical reaction of aromatic nitro compounds with potassium cyanide giving carboxylation ortho to the position of the former nitro group.

General Reaction Scheme
The reaction below shows the conversion of bromonitrobenzene into bromobenzoic acid. The reaction is an aromatic nucleophilic substitution. Instead of bromine, chlorine could be a substituent. It gives only small yields of up to 20%.

Reaction Mechanism
The Z in the following mechanism could be bromine or chlorine.

First, the cyanide attacks the carbon-atom in ortho-position to the nitro-group 1. After this the compound is aromatic again 2. In the next step, the negative charged oxygen-atom attacks the neighbor carbon-atom and an five-membered ring is build 3. It opens under building a carconlylic-group 4. Next, an other five-membered ring is built 5. After a condensation, a double bound is build between the two nitrogen-atoms 6. Elemental nitrogen is cut of for opening the ring 7. In the last step, the compound is protonated and the halogenbenzoic acid (8) is built.

Applications
This reaction has a limited application in organic synthesis.