Patent ID: 8222432

Claim:
A method of preparing pharmaceutical quality magnesium R-(+)-alpha-lipoate having greater than 95% purity and greater than 95% chiral purity, comprising: (a) preparing a clear solution of about two mole equivalents of R-(+)-alpha-lipoic acid having a chiral purity of about 95±5% in methanol and isopropyl alcohol and maintaining the lipoic acid solution under an inert gas and subdued lighting; (b) adding dropwise a volume of a solution of magnesium methoxide in methanol corresponding to about one mole equivalent of magnesium methoxide to the lipoic acid solution, thus providing a slurry of magnesium R-(+)-alpha-lipoate solid in the solution; and (c) isolating the magnesium R-(+)-alpha-lipoate.