Patents by Inventor Stephen L. J. Daren

Stephen L. J. Daren 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: 4835326
    Abstract: The invention relates to the stabilization of monobromostyrene of dibromostyrene and of mixtures of these. The stabilization is effected by means of hydroxy-benzene derivatives, where the benzene ring contains at least two substituents, one of these being a hydroxy group. The process is advantageously carried out by heating the styrene material with an excess of the inhibitor, distilling the monomer and adding an additional quantity of the inhibitor. The distilled monomer is preferably dried prior to the addition of the further quantity of inhibitor.
    Type: Grant
    Filed: July 20, 1987
    Date of Patent: May 30, 1989
    Assignee: Yeda Research and Development Company Limited
    Inventors: Stephen L. J. Daren, David Vofsi, Michael Peled
  • Patent number: 4748286
    Abstract: The invention relates to an improved process for the production of crystalline tribromostyrene. The process involves removal of hydrogen bromide in a two phase system with the aid of phase transfer catalysts. One of the phases used is an aqueous one containing an alkali metal hydroxide whereas the second comprises .beta.-bromoethyltribromobenzene in an alcohol as solvent.
    Type: Grant
    Filed: July 21, 1987
    Date of Patent: May 31, 1988
    Assignee: Yeda Research & Development Co. Ltd.
    Inventors: Stephen L. J. Daren, David Vofsi, Aurelia Finkels
  • Patent number: 4292453
    Abstract: The present invention relates to the production of ring-halogenated styrene monomers of high purity. These are of value in the production of polymers which possess flame retardance. The process of the invention comprises reacting heterogenously ring halogenated beta-bromoethyl benzene with a strong aqueous alkali base in the presence of a quaternary phase transfer catalyst until substantially all the bromoethyl benzene has undergone reaction, separating the phases, washing and neutralizing the organic phase and recovering the ring-halogenated styrene monomer, which is the desired product.
    Type: Grant
    Filed: May 24, 1979
    Date of Patent: September 29, 1981
    Assignee: Makhteshim Chemical Works Ltd.
    Inventors: Stephen L. J. Daren, David Vofsi, Meir Asscher