Patents by Inventor David D. C. Quan

David D. C. Quan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Process for the preparation of 1-(mercaptomethyl)-cyclopropaneacetic acid
    Patent number: 6512140
    Abstract: A process for the preparation of highly pure 1-(mercaptomethyl)-cyclopropaneacetic acid is described. Treatment of 1-(hydroxymethyl)-cyclopropaneacetonitrile with an acid provides the corresponding imino ester and/or halo-amide, which when reacted with thiourea provide the corresponding amide-isothiuronium salt. Hydrolysis of the amide-isothiuronium salt followed by an in situ oxidation allows the facile isolation and purification of 1-[1 -(carboxymethyl)-cyclopropanemethyldisulfanylmethyl]-cyclopropaneacetic acid (also known as 1-(mercaptomethyl)-cyclopropaneacetic acid disulfide). Reduction of the 1-(mercaptomethyl)-cyclopropaneacetic acid disulfide under mild conditions provides the 1-(mercaptomethyl)-cyclopropaneacetic acid with high purity.
    Type: Grant
    Filed: April 15, 2002
    Date of Patent: January 28, 2003
    Assignee: Delmar Chemicals Inc.
    Inventors: Lu Wei Liu, Yuan Wang, Hérika Marrugo, Sylvain Harper, David D. C. Quan, Zhihong (Nancy) Zhou, Gregory Bydlinski