Sodium Hydroxide → 2-Hydroxy-4-octadecenoic acid

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Reaction Steps

Methyl 2-hydroxy-4-octadecenoate (8.21 g, 0.026 mol, 1.0 eq) is heated under reflux with a large excess of sodium hydroxide (8.4 g, 0.21 mol, 8.1 eq) in water (20 ml) and methanol (20 ml) for 1 hour. After cooling down to room temperature, the mixture is washed with hexane (50 ml) and the organic phase separated. The clear aqueous layer is acidified to pH 1 with concentrated hydrochloric acid and the resultant mixture is extracted with diethylether (3×50 ml), the combined organic layers being washed with brine (50 ml) dried over anhydrous magnesium sulphate and evaporated to give a white solid. This is recrystallised from ethyl acetate/hexane to give the product acid (5) as white needles, 6.35 g (81%), mp 78-79.5° C.

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