Patents by Inventor Karl Stephan Nitsche

Karl Stephan Nitsche 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 4-hydroxy-1,2,2,6,6,-pentamethylpiperidine
    Patent number: 5840905
    Abstract: A process for the preparation of 4-hydroxy-1,2,2,6,6-pentamethylpiperidine (HPMP) from 4-oxo-2,2,6,6-tetramethylpiperidine (TAA) is described, in which TAA is first reduced to 4-hydroxy-2,2,6,6-tetramethylpiperidine (HTMP) by means of catalytic hydrogenation in water, the resulting crude solution, if desired after concentration by distillation, is reacted with formaldehyde or paraformaldehyde in at least 20% molar excess, and with formic acid, and the crude product melt separated from the reaction mixture is worked up by distillation.
    Type: Grant
    Filed: March 18, 1993
    Date of Patent: November 24, 1998
    Assignee: Ciba Specialty Chemicals Corporation
    Inventors: Karl Stephan Nitsche, Walter Wolf, Joachim Fries