# Hydrogenation with Diimide

## Reduction of Alkenes with Diimide: Experimental Procedure

The reduction is carried out at room temperature. Since diimide is an unstable compound, it has to be generated in situ for the . Several methods are available for the generation of diimide.

Examples for the generation of diimide:

• oxidation of hydrazine with hydrogen peroxide
• oxidation of hydrazine with oxygen and Cu(II)
• fragmentation of azodicarboxylic acid

Reaction of the generated diimide with is immediate and produces the desired product.

Azodicarboxamide is a good starting material for the most convenient in situ generation of diimide.

Fig.1
Fig.2

Preparation of potassium azodicarboxylate:

To a stirred aqueous solution of 40% potassium hydoxide is added at 0°C 5,0 $g$ of azodicarboxamide within 2 $h$. Stirring is continued for an additional 60 $min$ at 0$°C$. The yellow precipitate is filtered and washed with ice-cold methanol to yield after drying in high vacuum 7,3 $g$ (87 %) of potassium azodicarboxylate as a fine, crystalline powder .

Reduction:

To a solution of 2,0 $mmol$ alkene and 480 $mg$ (2,5 $mmol$ ) of potassium azodicarboxylate in 50 $mL$ of methanol a solution of 0,7 $mL$ (12 $mmol$ ) of glacial acetic acid dissolved in 5 $mL$ of methanol is slowly added dropwise at room temperature. The reaction mixture is stirred for several hours and subsequently worked up.

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