Patents by Inventor Visweswara R. Durvasula

Visweswara R. Durvasula 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: 5103042
    Abstract: Polyethers having terminal allyl unsaturation are subject to hydrogenolysis by reaction with a hydrogen donor in the presence of a n-allyl complex forming catalyst. The product polyethers have extremely low levels of unsaturation, and thus are useful in preparing polyurethanes having improved properties and processing.
    Type: Grant
    Filed: May 23, 1990
    Date of Patent: April 7, 1992
    Assignee: The Dow Chemical Company
    Inventors: Visweswara R. Durvasula, Franz J. Luxem
  • Patent number: 5079275
    Abstract: Disclosed is a class of poly(aminoaromatic) compounds (I) obtained by capping polymeric polyols or polythiols iwth aromatic amine groups wherein the latter groups are linked by --O-- or --S-- to the polyol (polythiol) residues. Also disclosed are the precursor poly(nitroaromatic) compounds (II) from which the compounds (I) are derived.The polyamines are characterized by amine reactivities in respect of isocyanate polyaddition reactions which allows for polymer reaction rates that are intermediate of prior art related polyamine compounds.Accordingly, the compounds (I) find their prime utility in the formation of synthetic resins containing polyurea linkages.
    Type: Grant
    Filed: April 10, 1989
    Date of Patent: January 7, 1992
    Assignee: The Dow Chemical Company
    Inventors: Visweswara R. Durvasula, Fred A. Stuber
  • Patent number: 4960950
    Abstract: Disclosed is a novel process for effecting an ether interchange reaction by heating together in the presence of a basic catalyst, a nitroaromatic ether or thioether and an organic compound containing at least one hydroxyl or mercapto group. The novelty resides particularly in carrying out the interchange in an inert solvent while sparging the heated reactants thereby to remove at least a portion of solvent along with an evolving alcohol or thiol.The process is particularly adapted to the capping of organic polyols with nitroaromatic ether groups. The capped products are useful as intermediates for the preparation of high molecular weight polyamines which in turn find utility in various polymer applications.
    Type: Grant
    Filed: March 28, 1988
    Date of Patent: October 2, 1990
    Assignee: The Dow Chemical Company
    Inventor: Visweswara R. Durvasula
  • Patent number: 4847416
    Abstract: Disclosed is a class of poly(aminoaromatic) compounds (I) obtained by capping polymeric polyols or polythiols with aromatic amine groups wherein the latter groups are linked by --O--or --S--to the polyol (polythiol) residues. Also disclosed are the precursor poly(nitroaromatic) compounds (II) from which the compounds (I) are derived.The polyamines are characterized by amine reactivities in respect of isocyanate polyaddition reactions which allows for polymer reaction rates that are intermediate of prior art related polyamine compounds.Accordingly, the compounds (I) find their prime utility in the formation of synthetic resins containing polyurea linkages.
    Type: Grant
    Filed: April 6, 1987
    Date of Patent: July 11, 1989
    Assignee: The Dow Chemical Company
    Inventors: Visweswara R. Durvasula, Fred A. Stuber
  • Patent number: 4612400
    Abstract: A method is described for autoxidizing a novel class of bis(ortho dialkyl-phenoxy)benzophenones directly to their corresponding dianhydrides. The method comprises autoxidizing the benzophenones in a solution of an aliphatic monocarboxylic acid having 3 to 8 carbon atoms with oxygen in the presence of a heavy metal oxidation catalyst and a promoter at a temperature of at least about 120.degree. C. to form the dianhydride.The dianhydrides are used in the preparation of organic high temperature polymers such as polyetherimides.
    Type: Grant
    Filed: December 20, 1985
    Date of Patent: September 16, 1986
    Assignee: The Dow Chemical Company
    Inventor: Visweswara R. Durvasula
  • Patent number: 4599445
    Abstract: A method is described for autoxidizing particular ortho-dialkyl substituted aromatic compounds using a particular type of solvent which gives rise to the formation of 3-alkanoyloxyphthalide compounds, some of which are novel.The phthalides in turn are ionically oxidized to their corresponding aromatic polycarboxylic acids.Combination of the two methods provides a means for converting ortho dialkyl substituted aromatic compounds directly to the corresponding polycarboxylic acids in higher yields and at generally lower overall temperatures and reaction conditions compared to prior art methods.Polycarboxylic acids so obtained are known to be useful in the preparation of alkyds, polyesters, and the like, and, particularly, in the formation of the corresponding acid anhydrides which are used in the preparation of organic high temperature polymers such as polyamides, polyamideimides, and polyimides.
    Type: Grant
    Filed: September 21, 1984
    Date of Patent: July 8, 1986
    Assignee: The Dow Chemical Company
    Inventor: Visweswara R. Durvasula
  • Patent number: 4577034
    Abstract: A method is described for autoxidizing a novel class of bis(ortho dialkyl-phenoxy)benzophenones directly to their corresponding dianhydrides. The method comprises autoxidizing the benzophenones in a solution of an aliphatic monocarboxylic acid having 3 to 8 carbon atoms with oxygen in the presence of a heavy metal oxidation catalyst and a promoter at a temperature of at least about 120.degree. C. to form the dianhydride.The dianhydrides are used in the preparation of organic high temperature polymers such as polyetherimides.
    Type: Grant
    Filed: February 14, 1985
    Date of Patent: March 18, 1986
    Assignee: The Dow Chemical Company
    Inventor: Visweswara R. Durvasula
  • Patent number: 4562271
    Abstract: A method is described for autoxidizing particular ortho-dialkyl substituted aromatic compounds using a particular type of solvent which gives rise to the formation of 3-alkanoyloxyphthalide compounds, some of which are novel.The phthalides in turn are ionically oxidized to their corresponding aromatic polycarboxylic acids.Combination of the two methods provides a means for converting ortho dialkyl substituted aromatic compounds directly to the corresponding polycarboxylic acids in higher yields and at generally lower overall temperatures and reaction conditions compared to prior art methods.Polycarboxylic acids so obtained are known to be useful in the preparation of alkyds, polyesters, and the like, and, particularly, in the formation of the corresponding acid anhydrides which are used in the preparation of organic high temperature polymers such as polyamides, polyamideimides, and polyimides.
    Type: Grant
    Filed: September 21, 1984
    Date of Patent: December 31, 1985
    Assignee: The UpJohn Company
    Inventor: Visweswara R. Durvasula
  • Patent number: 4526984
    Abstract: A method is described for autoxidizing ortho-dialkyl substituted aromatic ethers directly to their corresponding carboxylic acid anhydrides. The method comprises autoxidizing the ethers in a first step in a solution of an aliphatic monocarboxylic acid having 2 to 8 carbon atoms to form a partially oxidized reaction mixture. The autoxidation of the partially oxidized mixture is continued in a second step after the addition of an anhydride of an aliphatic monocarboxylic acid having 3 to 8 carbon atoms and at a temperature of at least 130.degree. C. to form said anhydrides.The anhydrides are used in the preparation of organic high temperature polymers such as polyamideimides, polyimides, polyetherimides, and polyetherimideamides.
    Type: Grant
    Filed: October 29, 1984
    Date of Patent: July 2, 1985
    Assignee: The Upjohn Company
    Inventor: Visweswara R. Durvasula
  • Patent number: 4485247
    Abstract: A method is described for autoxidizing particular ortho-dialkyl substituted aromatic compounds using a particular type of solvent which gives rise to the formation of 3-alkanoyloxyphthalide compounds, some of which are novel.The phthalides in turn are ionically oxidized to their corresponding aromatic polycarboxylic acids.Combination of the two methods provides a means for converting ortho dialkyl substituted aromatic compounds directly to the corresponding polycarboxylic acids in higher yields and at generally lower overall temperatures and reaction conditions compared to prior art methods.Polycarboxylic acids so obtained are known to be useful in the preparation of alkyds, polyesters, and the like, and, particularly, in the formation of the corresponding acid anhydrides which are used in the preparation of organic high temperature polymers such as polyamides, polyamideimides, and polyimides.
    Type: Grant
    Filed: January 24, 1983
    Date of Patent: November 27, 1984
    Assignee: The Upjohn Company
    Inventor: Visweswara R. Durvasula