Reduction of azines, hydrazones, hydrazines, and hydrazides

Mild reduction converts azines and hydrazines into disubstituted hydrazines, but under vigorous conditions reductive cleavage of the N-N bond affords amines. Reduction of oximes thus affords a further but seldom used method of converting carbonyl compounds into amines. 

Catalysts that are active for hydrogenation can be used equally for hydro-genolysis of an N-N bond Raney nickel is the catalyst of choice for this purpose 162 use of platinum or palladium catalysts generally leads only to the substituted hydrazine,144 145 N-N fission being rare in these cases.146 Experience to date does not permit prediction with certainty as to which compounds will suffer N-N fission on noble-metal catalysts it has been observed mainly with hydrazones and azines of aromatic aldehydes, but such catalysts have often been used in acid solution for reduction of hydrazones and azines to the corresponding hydrazines. 

Hydrogenolysis of the N-N bond is best achieved directly by use of Raney nickel alloy in an alkaline medium,147 and this reaction has been used to clarify the constitution of hydrazine derivatives.128 

Hydrazides of carboxylic144 148 and sulfonic acids144,148,149 are cleaved to amides by hydrogenation over Raney nickel in boiling alcohol  

General procedure A mixture of a hydrazide (1-2 g), 95% ethanol (100 ml), and Raney nickel (10 g) is stirred and heated under reflux for 3 h, then filtered and evaporated. The residue is extracted with hot water or benzene. As the extract cools, the amide is obtained in 60-80% yield. 

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