Hydrochloric Acid → 2,5,8,11,14,17,20-Heptaoxadocosan-22-oic acid

The product of step (a) (4.54 g) was dissolved in an aqueous sodium hydroxide solution (0.1M) (45 ml) and the reaction was stirred at room temperature for 20 hours. The reaction mixture was acidified to pH 2 by the addition of hydrochloric acid (2M), then this was diluted with brine (300 ml) and extracted with dichloromethane (3×300 ml). The combined organic layers were dried and the solvent removed in vacuo to give the title compound as a yellow oil (3.75 g).