Water → Lipoic acid

Participants

Reaction Steps

125.5 g of the dihydrolipoic acid solution are stirred in 5 l of completely deionized water in a 10 l round-bottomed flask, and the solution is adjusted to pH 8.5 using dilute sodium hydroxide solution and treated with catalytic amounts of Fe(III) sulfate solution. Air is introduced until the color lightens. After addition of 600 ml of toluene, the mixture is adjusted to pH 2 using H2SO4. The phases are separated and the water phase is extracted once with toluene. The combined toluene phases are concentrated to about 25% of the volume. The residue is treated with 600 ml of heptane, stirred under nitrogen and then forced through a filter loaded with silica gel. The filter is washed with toluene/heptane mixture.

Provenance & Evidence