Patents by Inventor Hans E. Schoemaker

Hans E. Schoemaker 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 racemizing an optically active N-benzylidene amino-acid amide
    Patent number: 5047585
    Abstract: The invention relates to a process for racemizing an optically active N-benzylidene amino-acid amide, characterized in that a solution of the N-benzylidene amino-acid amide is mixed in a water-miscible organic solvent with at least 0.05 mole strong base per liter solution.The invention further relates to a process for preparing an L-amino acid by enzymatic separation of the corresponding DL-amino-acid amide with an enzyme preparation from Pseudomonas putida, in which process also uncoverted D-amino-acid amide is left behind in solution, characterized in that benzaldehyde is added to the solution, during which addition a precipitate of D-N-benzylidene amino-acid amide is being formed, this precipitate is subsequently, after being separated off, dissolved in an acetone-water mixture, 0.08-0.15 mole KOH/liter solution is subsequently added, the resulting solution is stirred for 1-20 hours at 20.degree.-60.degree. C.
    Type: Grant
    Filed: April 3, 1989
    Date of Patent: September 10, 1991
    Assignee: Stamicarbon B.V.
    Inventors: Wilhelmus H. J. Boesten, Hans E. Schoemaker, Bernardus H. N. Dassen
  • Process for racemizing an optically active N-benzylidene amino-acid amide
    Patent number: 4847412
    Abstract: The invention relates to a process for racemizing an optically active N-benzylidene amino-acid amide, characterized in that a solution of the N-benzylidene amino-acid amide is mixed in a water-miscible organic solvent with at least 0.05 mole strong base per liter solution.The invention further relates to a process for preparing an L-amino acid by enzymatic separation of the corresponding DL-amino-acid amide with an enzyme preparation from Pseudomonas putida, in which process also unconverted D-amino-acid amide is left behind in solution, characterized in that benzaldehyde is added to the solution, during which addition a precipitate of D-N-benzylidene amino-acid amide is being formed, this precipitate is subsequently, after being separated off, dissolved in an acetone-water mixture, 0.08-0.15 mole KOH/liter solution is subsequently added, the resulting solution is stirred for 1-20 hours at 20.degree.-60.degree. C.
    Type: Grant
    Filed: April 10, 1986
    Date of Patent: July 11, 1989
    Assignee: Stamicarbon B.V.
    Inventors: Wilhelmus H. J. Boesten, Hans E. Schoemaker, Bernardus H. N. Dassen