Dipotassium azodicarboxylate

Reviews. Hamersma and Snyder studied the effect of variation in reaction conditions in reductions with diimide generated from dipotassium azodicarboxylate. Air does not have a deleterious effect. Rate of reduction decreases with solvents in the following order pyridine > dioxane > dimethyl sulfoxide > methanol > ethanol > n-butanol, Water is a powerful inhibitor of the reaction in nonhydroxylic solvents but has practically no effect in hydroxylic solvents. 

Dipotassium azodicarboxylate (2), prepared by hydrolysis of azodicarboxamide (1), is a less convenient source since a large excess of reagent is required. A 00 00 ... 

Dipotassium azodicarboxylate (DAPA) (20 mg, 0.123 mmol) was added to a solution of the isomeric olefin (149 mg, 0.197 mmol) in methanol (10 mL). Glacial acetic acid (10 pL) was added, and the reaction mixture was heated to 40 °C open to the atmosphere. As the yellow color of the solution started to fade, more DAPA (20 mg) and acetic acid (10 pL) were added. The addition procedure was repeated several times over the course of 10 h, and the reaction progress was monitored by NMR. On completion of the reaction, the reaction mixture was cooled and then a saturated aqueous solution of NaHCOs (15 mL) was added. The product was then extracted into CI bCb (3 X 25 mL), and the combined organic layers were dried over Na2SO4. After evaporation of the solvent, the clear residue was purified by chromatography (2 1, hexaneiEtOAc) to give 130 mg (87%) of the reduced product as a clear oil. 

The first of the above three methods, involving aerial or H202-mediated oxidation of hydrazine, is the traditional route to diimide. Acidification of dipotassium azodicarboxylate is another common route, which is analyzed below in some detail. Protonation of the nitrogens leads to spontaneous decarboxylation of the azodicarboxylate anion, as shown below ... 

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