SYNTHESIS OF OCTANAL

• A 60 per cent oil suspension of sodium hydride (160 mg, 4mmol) 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 (318mg, 2mmol) 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 50 g 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. 2 ml 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. 

Notes to keep in mind:

1. E. Merck Silica gel 60 (40-63 ^m) stirred with acetone for 30 minutes, filtered, air-dried, and then oven-dried at 120°C for 12 hours.