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).
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Patent number: 5103042Abstract: 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: GrantFiled: May 23, 1990Date of Patent: April 7, 1992Assignee: The Dow Chemical CompanyInventors: Visweswara R. Durvasula, Franz J. Luxem
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Patent number: 5079275Abstract: 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: GrantFiled: April 10, 1989Date of Patent: January 7, 1992Assignee: The Dow Chemical CompanyInventors: Visweswara R. Durvasula, Fred A. Stuber
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Patent number: 4960950Abstract: 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: GrantFiled: March 28, 1988Date of Patent: October 2, 1990Assignee: The Dow Chemical CompanyInventor: Visweswara R. Durvasula
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Patent number: 4847416Abstract: 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: GrantFiled: April 6, 1987Date of Patent: July 11, 1989Assignee: The Dow Chemical CompanyInventors: Visweswara R. Durvasula, Fred A. Stuber
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Patent number: 4612400Abstract: 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: GrantFiled: December 20, 1985Date of Patent: September 16, 1986Assignee: The Dow Chemical CompanyInventor: Visweswara R. Durvasula
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Patent number: 4599445Abstract: 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: GrantFiled: September 21, 1984Date of Patent: July 8, 1986Assignee: The Dow Chemical CompanyInventor: Visweswara R. Durvasula
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Patent number: 4577034Abstract: 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: GrantFiled: February 14, 1985Date of Patent: March 18, 1986Assignee: The Dow Chemical CompanyInventor: Visweswara R. Durvasula
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Patent number: 4562271Abstract: 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: GrantFiled: September 21, 1984Date of Patent: December 31, 1985Assignee: The UpJohn CompanyInventor: Visweswara R. Durvasula
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Patent number: 4526984Abstract: 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: GrantFiled: October 29, 1984Date of Patent: July 2, 1985Assignee: The Upjohn CompanyInventor: Visweswara R. Durvasula
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Patent number: 4485247Abstract: 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: GrantFiled: January 24, 1983Date of Patent: November 27, 1984Assignee: The Upjohn CompanyInventor: Visweswara R. Durvasula