SYNTHESIS OF HEXANE

STEP 1: In a suitably equipped 500 ml three-necked flask prepare an ether solution (100 ml) of hexylmagnesium bromide from 12 g (0.5 mol) of magnesium turn­ings and 82.5 g (70.5 ml, 0.5 mol) of dry 1-bromohexane. 

STEP 2: When most of the magnesium has dis­appeared (about 4 hours) add AnalaR ammonium chloride (27 g) and leave the reaction mixture overnight. 

STEP 3: Cool the flask in ice and add slowly a large excess of dilute hydrochloric acid; the precipitate will dissolve completely. 

STEP 4: Separate the upper ethereal layer, and wash it successively with dilute hydro­chloric acid and water; dry with magnesium sulphate or anhydrous calcium sulphate.

STEP 5:  Distil the ethereal solution through an efficient fractionating col­umn (e.g. a Hempel column filled with 6-mm glass or porcelain rings, or a 30-cm all-glass Dufton column). 

STEP 6: After the ether has passed over, hexane will distil at 67-70 °C (13-14 g, 30-33%). Record the i.r. spectrum and compare it with Fig. 3.13(a). The m.s. shows principal frag­ment ions at m/z 86 (M), 57 (M — C₂H₅, base peak), 43 (M — C₃H₇) and 29 (C2H5^6°)•