SYNTHESIS OF 2-NITROOCTANE

CAUTION: Nitroalkanes should always be distilled in apparatus sited behind a safety screen.

• 2-Iodooctane (71.2g, 0.30 ml) is poured into a stirred solution of 225 ml of dimethyl sulphoxide and 36g of sodium nitrite (0.52 mol) contained in a 500-ml flask immersed in a water bath held at room temperature. 

• Stirring is continued for 4 hours. 

• The reaction mixture is poured into 600 ml of ice-water layered over with light petroleum (b.p. 35-37 °C). 

• After separation the aqueous phase is further extracted with four 100-ml portions of light petroleum. 

• The combined organic extracts are washed with four 100-ml portions of water and dried over magnesium sulphate. 

• The drying agent is removed by filtration and the light petroleum solution is distilled through a small fractionating column at atmospheric pressure, after which the residue is distilled under reduced pressure. 

• The following fractions are obtained: (i) 14.0g (30%) of 2-octyl nitrite, b.p. 32°C/2mmHg, nᴅ²¹ 1.4089; (ii) 3.9g, b.p. 53-56 °C/ ImmHg, nᴅ²¹ 1.4111-1.4382; and (iii) 27g (58%), b.p. 61 °C/1 mmHg of 2-nitrooctane, nᴅ²¹ 1.4281.

Cognate preparation: Nitrocyclopentane

• Use cyclopentyl bromide (22.0g, 0.15mol), sodium nitrite (18g, 0.26mol) and 100ml of dimethyl sulphoxide; allow the reaction mixture to stir at 15°C for 3 hours. 

• The product (9.9g, 58%), b.p. 62°C/8mmHg,nᴅ²¹ 1.4538, was isolated as above.