[4910-62-7] · C2K2N2O4 · Potassium Azodicarboxylate · (MW 194.24)
(used for the generation of diimide1)
Alternate Name: azodicarboxylic acid, potassium salt.
Physical Data: crystalline yellow solid; properties do not appear to be recorded.
Solubility: insol aprotic organic solvents; partially sol protic organic and aqueous organic solvents.
Form Supplied in: not currently commercially available.
Preparative Method: by the reaction of potassium hydroxide with H2NCON=NCONH22 (which is commercially available).
Handling, Storage, and Precautions: there has been one report that potassium azodicarboxylate exploded violently when left exposed to bright sunlight for about 30 min;3 there have been other reports of suspected nonviolent decomposition of the compound on storage;4 it is advisable to dry the compound in vacuo and not store in a sealed container. Extreme care must be exercised in the preparation, isolation, storage, and use of potassium azodicarboxylate.
The treatment of potassium azodicarboxylate with a carboxylic acid in protic or aprotic organic solvents results in the ultimate formation of Diimide, which is a very useful reagent for the mild, noncatalytic reduction of C-C p-systems. Potassium azodicarboxylate is prepared by the reaction of Potassium Hydroxide with azodicarboxamide (eq 1).2
The use of potassium azodicarboxylate as a source of diimide is particularly useful for the generation of deuterium- and tritium-labeled diimide in aprotic organic solvents for the position-, facial- and stereoselective reduction of C-C p-systems, as illustrated in eq 2.5 In these reduction reactions the substrate and an excess of the potassium azodicarboxylate are placed in an appropriate solvent and a slight excess of the carboxylic acid is slowly added to the mixture. The yields of product are generally very high.
This procedure is also very useful for the syn reduction of alkynyl halides, as illustrated in eq 3.6
Daniel J. Pasto
University of Notre Dame, IN, USA