Process for purifying thioctic acid in water

Details Process for purifying thioctic acid in water Process for purifying thioctic acid in water

2006-03-21

2009-06-16

Oh, Taylor Victor (Department: 1625)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

Reexamination Certificate

active

07547792

ABSTRACT:
Process for purifying thioctic acid in water comprising the following steps: a) dissolving the thioctic acid in an aqueous alkaline solution or alternatively dissolving a thioctic acid salt, if necessary adjusting the pH to alkaline values, b) acidifying the solution from step (a) with an acid chosen from the class consisting of sulfuric acid, phosphoric acid, methanesulfonic acid to a pH between 5.4 and 5.8. c) isolating the thioctic acid precipitated in step (b) by conventional methods.

REFERENCES:
patent: 6462202 (2002-10-01), Schuhbauer et al.
Christophe Crevisy et al., A New Iron-Mediated Strategy for the Synthesis of a-Lipoic Acid and Analogues; Eur. J. Org. Chem. 1998, pp. 1949-1954.
N.W. Fadnavis, et al., Lipase Catalyzed Regio- and Stereospecific Hydrolysis: Chemoenzymatic Synthesis of Both (R)- and (S)-enantiomers of a-Lipoic Acid; Tetrahedron: Asymmetry 9 (1998) pp. 4109-4112.
Preeti Dhar, et al., Piperidinium Tetrathiotungstate as Sulfur Transfer Reagant: Synthesis of Cyclic Disulfides; J. Org. Chem. 1992, 57, pp. 1699-1702.
Michael H. Brookes, et al., Synthesis of a-(R)- and a-(S)-Lipoic Acid from (S)-Malic Acid; J. Chem. Soc. Perkin Trans. 1 (1988) pp. 9-12.
Augusto Segre, et al., A New Synthesis of 6-Thioctic Acid (DL-a-Lipoic Acid); 6-Thioctic Acid, Jul. 5, 1957, pp. 3503-3505.
Edward Walton, et al., Synthesis of (+)-a-Lipoic Acid and Its Optical Antipode; JACS (1955) vol. 77, pp. 5144-5149.
D.S. Acker et al., Synthesis of Racemic, Optically Active and Radioactive a-Lipoic Acids; JACS (1957) pp. 6483-6487.

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