Patents by Inventor David Losan Ho

David Losan Ho 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).

  • Patent number: 8258291
    Abstract: In one embodiment of the invention a method to prepare sucralose-6 -acylate through chlorinating sucrose-6-acylate by BTC in the process of sucralose preparation is disclosed. In this embodiment a Vilsmeier reagent is firstly prepared below 0° C. by dissolving BTC in DMF or in component solvent, containing DMF, toluene, dichloroethane, chloroform and carbon tetrachloride. Consequently, sucrose-6-ester was chlorinated by Vilsmeier reagent. BTC can also be dissolved in one or several organic solvent such as toluene, dichloroethane, chloroform and carbon tetrachloride, and added to a DMF solution of sucrose-6-acylate for chlorination. Sucralose was prepared through de-esterifying the obtained sucralose 6-ester using sodium methoxide/methanol or sodium ethoxide/ethanol.
    Type: Grant
    Filed: October 25, 2006
    Date of Patent: September 4, 2012
    Assignee: Mamtek International Limited
    Inventors: David Losan Ho, Wan Zhenghao
  • Publication number: 20110175022
    Abstract: The present invention provides a method for preparing DMF for sucralose production, including, e.g., isolating DMF from a composition comprising DMF, water, and methanol, using a single-tower rectification system. In various embodiments of the present invention, the composition, after the removal of water and methanol, may be further dried/dehydrated, such as, by using a dehydration agent and/or filtration. The resulting substantially pure DMF may comprise at least about 98-99% DMF. The present invention further provides a method of preparing a composition comprising anhydrous sucrose for sucralose production, which may comprise mixing regular sucrose with a water-containing DMF composition, and drying the resulting sucrose-DMF composition. Also provided is a single-tower separation system for isolating DMF from a composition comprising DMF, water, and methanol.
    Type: Application
    Filed: October 21, 2010
    Publication date: July 21, 2011
    Inventors: David Losan Ho, Zhenghao Wan
  • Patent number: 7862744
    Abstract: The present invention provides a method for preparing DMF for sucralose production, including, e.g., isolating DMF from a composition comprising DMF, water, and methanol, using a single-tower rectification system. In various embodiments of the present invention, the composition, after the removal of water and methanol, may be further dried/dehydrated, such as, by using a dehydration agent and/or filtration. The resulting substantially pure DMF may comprise at least about 98-99% DMF. The present invention further provides a method of preparing a composition comprising anhydrous sucrose for sucralose production, which may comprise mixing regular sucrose with a water-containing DMF composition, and drying the resulting sucrose-DMF composition. Also provided is a single-tower separation system for isolating DMF from a composition comprising DMF, water, and methanol.
    Type: Grant
    Filed: July 23, 2008
    Date of Patent: January 4, 2011
    Assignee: Mamtek International Limited
    Inventors: David Losan Ho, Zhenghao Wan
  • Publication number: 20100022765
    Abstract: The present invention provides a method for purifying sucralose-6-ester for use in making sucralose, wherein the method eliminates the need of an esterification process. In particular, ethyl acetate and ether are used to extract and purify sucralose-6-ester from a sucralose production intermediate composition comprising sucralose-6-ester.
    Type: Application
    Filed: July 23, 2008
    Publication date: January 28, 2010
    Inventors: David Losan Ho, Zhenghao Wan
  • Publication number: 20100019195
    Abstract: The present invention provides a method for preparing DMF for sucralose production, including, e.g., isolating DMF from a composition comprising DMF, water, and methanol, using a single-tower rectification system. In various embodiments of the present invention, the composition, after the removal of water and methanol, may be further dried/dehydrated, such as, by using a dehydration agent and/or filtration. The resulting substantially pure DMF may comprise at least about 98-99% DMF. The present invention further provides a method of preparing a composition comprising anhydrous sucrose for sucralose production, which may comprise mixing regular sucrose with a water-containing DMF composition, and drying the resulting sucrose-DMF composition. Also provided is a single-tower separation system for isolating DMF from a composition comprising DMF, water, and methanol.
    Type: Application
    Filed: July 23, 2008
    Publication date: January 28, 2010
    Inventors: David Losan Ho, Zhenghao Wan
  • Publication number: 20080103298
    Abstract: In one embodiment of the invention a method to prepare sucralose-6-acylate through chlorinating sucrose-6-acylater by BTC in the process of sucralose preparation is disclosed. In this embodiment a Vilsmeier reagent is firstly prepared below 0° C. by dissolving BTC in DMF or in component solvent, containing DMF, toluene, dichloroethane, chloroform and carbon tetrachloride. Consequently, sucrose-6-ester was chlorinated by Vilsmeier reagent. BTC can also be dissolved in one or several organic solvent such as toluene, dichloroethane, chloroform and carbon tetrachloride, and added to a DMF solution of sucrose-6-acylate for chlorination. Sucralose was prepared through de-esterifying the obtained sucralosed 6-ester using sodium methoxide/methanol or sodium ethoxide/ethanol.
    Type: Application
    Filed: October 25, 2006
    Publication date: May 1, 2008
    Inventors: David Losan Ho, Wan Zhenghao
  • Publication number: 20080103295
    Abstract: One embodiment of the present invention is a process of making sucrose-6-ester from sucrose by transesterification in the presence of a solid super acid catalyst such as SO42?—TiO2/Al2O3 or SO42?—TiO2. The sucrose-6-acetate is then chlorinated to afford sucralose-6-acetate, using BTC or thionyl chloride. Sucralose-6-acetate is converted into TPSGA for the purpose of purification. TPSGA is de-esterified by sodium methoxide/methanol or sodium ethoxide/ethanol to give sucralose.
    Type: Application
    Filed: October 25, 2006
    Publication date: May 1, 2008
    Inventors: David Losan Ho, Wan Zhenghao