Sciencemadness Discussion Board

Zn-Ni reduction of aliphatic nitriles? Could HCOONH4 synergise?

Alchemica - 4-3-2026 at 05:36

Been looking into the Zn-Ni couple for reduction of nitriles to the corresponding amines. Anyone have experience using such, particularly for aliphatic nitriles?

The plain Zn-Ni/H2O system as described by Sakai et al. 1968, see https://doi.org/10.1246/bcsj.41.1902 , has been used to reduce aromatic nitriles to benzonitriles but was wondering if this metal system might couple particularly well with HCOONH4 to reduce substrates via the initial Zn-Ni mediated process but also using the ammonium formate, via a catalytic transfer hydrogenation process using the finely divided Ni, as an Urushibara-like catalyst (? rivaling Raney nickel) to reduce other/more challenging substrates like the aliphatic nitriles to the amine?


Zn-Ni works well for PhCN, affording the amine in 90% yield.
Quote:
Precipitated Metals. Zinc dust (10g) and distilled water (3ml) were placed in an Erlenmeyer flask and heated on a water bath. An aqueous solution (10ml) containing either 4.04g of nickel(II) chloride(NiCl2.6H20),2) 4.04g of cobalt (II) chloride (CoCl2.6H2O), 2.69g of copper(II) chloride (CuCl2.H2O), or 4.84g of iron (III) chloride (anhydrous), previously heated to 60C, was added to the heated zinc dust mud with vigorous shaking.

A violent exchange reaction took place, depositing nickel on the surface of the zinc dust. The whole solid was collected on a glass filter by suction, washed with water three times and then with methanol and ether, and dried under reduced pressure.

The precipitated metal thus obtained contains about 1g of each metal, supported on the zinc dust.


I used MeCN as a model substrate and while I have to still work-up, the smell is right.

 
Quote:
Reduction of Styrene. A suspension of styrene (10g) in 100ml of water was refluxed vigorously in the presence of the ppt-Ni containing 4g of nickel. After the solution had been refluxed for 12hr, the ppt-Ni was separated by filtration while hot, and washed with water and with ether.

The filtrate and the washings were combined and extracted with ether. The extract was dried over anhydrous magnesium sulfate, and the ether was
carefully evaporated away on a water bath. The residue was analyzed by gas chromatography (column, 30% Carbowax 1500 on Celite 30-40 meshes; length, 2m; column temp., ca. 180℃; flow rate, 14-20cm/sec; carrier gas, H2). The yield of ethylbenzene was 81.4%. The ethylbenzene (bp 129-131℃) was identified by infrared spectrum analysis.

The Reduction of Benzonitrile. The reaction procedure was almost the same as that described above. After the reaction, the ppt-Ni was filtered off. The filtrate was carefully evaporated to dryness under reduced pressure, and the residue was extracted with ether. The evaporation of the ether extract gave a small quantity of a white solid which was identified as benzamide. A major part of the product, which consisted of a white solid insoluble in ether, was recrystallized from hot water (mp >240℃). It was identified as benzylamine hydrochloride by IR analysis (vKBrmax 3012,1520,1500,750, and 695cm-1) and by NMR analysis (benzene ring protons τ 2.55, methylene protons τ 5.8 in D2O). The hydrochloride (yield, ca. 90%) liberated benzylamine when treated with sodium hydroxide.


Will update soon.

[Edited on 4-3-2026 by Alchemica]

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[Edited on 4-3-2026 by Alchemica]