The oxidative hydrolysis of nitronate salts derived from primary nitroalkanes

7 THE OXIDATIVE HYDROLYSIS OF NITRONATE SALTS DERIVED FROM PRIMARY NITROALKANES 

The hydrolysis of the conjugate base of a primary nitroalkane to an aldehyde under acidic conditions is known as the Nef reaction (cf. Section 5.8.7, p. 623). 

The usefulness of the nitronate anion from a primary nitroalkane as an acyl anion equivalent (see Appendix A6.2) is further illustrated by the fact that it may be reacted with other electrophiles, prior to the conversion into the carbonyl group.120 An example of its use in this manner is illustrated in Expt 5.178. 

A 60 per cent oil suspension of sodium hydride (160 mg, 4 mmol) is washed free of oil with pentane and transferred to a nitrogen-filled flask with the aid of 20 ml of t-butyl alcohol. After stirring this mixture for 10 minutes, a solution of 1-nitrooctane (318 mg, 2 mmol) in 40 ml of t-butyl alcohol is added all at once a heavy white precipitate formed immediately. The mixture is stirred for 20 minutes and then 600 ml of ice-cold pentane is added this was followed at once by 50g of ice and an ice-cold solution of 316mg (2mmol) of potassium permanganate and 248 mg (4 mmol) of boric acid in 80 ml of water. The mixture is stirred vigorously under nitrogen for 10 minutes and then 2 ml of aqueous 1 m sodium metabisulphite and 4 ml of 1 m sulphuric acid are added. 

The pentane layer is separated and the aqueous layer is extracted twice with 60-ml portions of pentane. The combined pentane solutions are washed three times with 400-ml portions of ice-cold water and dried over magnesium sulphate under nitrogen. Removal of the pentane under vacuum gives 249 mg (97%) of crude aldehyde 240 mg of this oil is dissolved in c.2ml of pentane and filtered through a 3 cm x 2.5 cm column of deactivated silica gel (1) and the column eluted with pentane. Removal of the pentane gives 215 mg (89%) of a very pale yellow oil. Spectra (n.m.r. and i.r.) show the oil to be pure octanal. 

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The oxidative hydrolysis of nitronate salts derived from primary nitroalkanes (Expt 5.84). 

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