Nickel(II) 2-Ethylhexanoate

[4454-16-4]  · C16H30NiO4  · Nickel(II) 2-Ethylhexanoate  · (MW 345.15)

(catalyst in conjunction with bromine for regioselective oxidation of diols and conversion of diols to lactones1,2)

Solubility: sol toluene, xylenes; slightly sol hexane.

Form Supplied in: available as a viscous solution in mineral spirits containing 10-15 wt % Ni. Contains excess 2-ethylhexanoic acid.

Analysis of Reagent Purity: elemental analysis of Ni (weight percent).

Handling, Storage, and Precautions: not hygroscopic; nickel compounds are cancer suspect agents.

Oxidation of Alcohols.

Nickel(II) 2-ethylhexanoate is used in conjunction with anhydrous Bromine in acetonitrile for the selective oxidation of 1,4-diols in which one alcohol moiety is primary and one is secondary.1 The reaction leads to selective oxidation of the primary alcohol and concomitant cyclization to a lactone. In the case of 1,4-butanediols with substituents in the 2 position, the less sterically hindered of the two primary alcohol groups is preferentially oxidized (eq 1).2 The steric bulk of 2-ethylhexanoate is also an important factor in comparison to other nickel carboxylates such as Nickel(II) Acetate, nickel(II) benzoate, and nickel(II) pivalate. Use of chlorine or NaOCl in place of bromine gives inferior results.

Reactions are carried out in acetonitrile at room temperature for 1 h using 8 mol Br2 and 5 mol nickel compound per mol of diol. Some adjustment of the molar ratio of bromine may be necessary to give optimal regioselectivity.

1. Doyle, M. P.; Bagheri, V. JOC 1981, 46, 4806.
2. Doyle, M. P.; Dow, R. L.; Bagheri, V.; Patrie, W. J. JOC 1983, 48, 476.

Cynthia J. Burrows & Shiow-Jyi Wey

State University of New York at Stony Brook, NY, USA

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