Nickel, Raney-sodium hypophosphite

Nicotinonitrile gives a high yield (70 per cent) of the aldehyde when reduced with Raney nickel and sodium hypophosphite. Raney nickel with formic acid is less efficient . 

This reduction has also been achieved by treating the nitrile with sodium hypophosphite (NaH2P02 ) and Raney nickel in aqueous acetic acid - pyridine or formic acid. 

An alternative method for the conversion of aromatic nitriles to aldehydes is their heating with Raney nickel and sodium hypophosphite in water-acetic acid-pyridine (1 1 2) at 40-45° for 1-1.5 hours (yields 40-90%) [1154], or heating with Raney nickel and formic acid at 75-80° for 30 minutes (yields 35-83%) [7/55], or even their refluxing for 30 minutes with Raney nickel alloy in 75% aqueous formic acid (yields 44-100%) [1156]. 

Reduction of nitroalkenes. Vinyl nitro compounds are reduced to saturated ketones or aldehydes by Raney nickel and an aqueous solution of sodium hypophosphite. Ester groups, C=C bonds, and aryl NO, and halo groups are not reduced. Under these conditions nitroalkanes arc reduced to amines, and oximes are converted into carbonyl compounds in high yield. 

Sitrile — aldehyde (1, 725-726 2,293). The nitriles 1 and 2 are reduced with W2 Raney nickel in a slightly acidic buffer system to give the corresponding aldehydes in 72-74% yield. Additional reducing agents (sodium hypophosphite, formic acid, or H2), which are commonly needed in similar reactions, are not required. 

Raney nickel hydrogenation of nitriles is aqueous acetic acid or in aqueous acetic acid-pyridine in the presence of sodium hypophosphite (NaH PO-i), which becomes oxidized to the phosphate, converts the nitriles into the corresponding aldehydes. The reaction takes place at room temperature and pressure. Yields are in the range 50-90%. Thus a solution of 1 g. of benzonitrile and 2 g. of hydrated sodium hypo-phosphite in 29 ml. of a 1 1 2 water-acetic acid-pyridine mixture was stirred with 0.3-0.4 g. of Raney nickel at 40-45° for 1 hr. benzaldehyde was isolated as the 2,4-dinitrophenylhydrazone. 

P-Ketoesters. /3,y-Unsaturated )3-nitro esters undergo reductive Nef reaction in the presence of Raney nickel and sodium hypophosphite in a buffered medium. 

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