Patents by Inventor Rajiv Dhawan

Rajiv Dhawan 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).

  • 2,4,5-triaminophenols and related compounds
    Patent number: 8664348
    Abstract: New triaminophenol compositions and related compounds are disclosed, as are processes for their preparation and for the preparation of novel salts and diacid complexes from such compounds. Polymers prepared from these compositions can be made into high strength fiber, film, and tape and are useful in applications such as protective apparel, aircraft, automotive components, personal electronics, and sports equipment.
    Type: Grant
    Filed: December 21, 2010
    Date of Patent: March 4, 2014
    Assignee: E I du Pont de Nemours and Company
    Inventors: Rajiv Dhawan, Joachim C Ritter, Frederick K Mallon, Steven R Allen, David J Rodini, Roger K Siemionko
  • 2,4,5-triaminophenols and related compounds
    Patent number: 8580910
    Abstract: New triaminophenol compositions and related compounds are disclosed, as are processes for their preparation and for the preparation of novel salts and diacid complexes from such compounds. Polymers prepared from these compositions can be made into high strength fiber, film, and tape and are useful in applications such as protective apparel, aircraft, automotive components, personal electronics, and sports equipment.
    Type: Grant
    Filed: December 21, 2010
    Date of Patent: November 12, 2013
    Assignee: E I du Pont de Nemours and Company
    Inventors: Rajiv Dhawan, Annalisa Hargis, Joachim C Ritter
  • INTEGRATED PROCESSES FOR THE PREPARATION OF POLYBENZIMIDAZOLE PRECURSORS
    Publication number: 20130172621
    Abstract: An integrated process is provided for efficiently preparing 2,4,5-triaminophenol, starting with nitration of 2,6-dihalobenzene; high purity salts thereof; and complexes of 2,4,5-triaminophenol aromatic diacids, which are precursors for making polybenzimidazole polymer for high performance fibers. The process design eliminates several costly intermediate drying and recrystallization steps. The handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
    Type: Application
    Filed: December 21, 2010
    Publication date: July 4, 2013
    Applicant: E.I.Du Pont de Nemours and Company
    Inventors: Rajiv Dhawan, Annalisa Hargis, Joachim C. Ritter
  • Process for the preparation of monomers for polybenzimidazole materials
    Patent number: 8431747
    Abstract: A process is provided to produce 2,3,5,6-tetraaminotoluene. Highly pure salts of 2,3,5,6-tetraaminotoluene are produced via reduction of 2,6-diamino-3,5-dinitrotoluene. The 2,3,5,6-tetraaminotoluene salt is precipitated as a clean (>99% purity) product. The salt is a precursor for monomers to make a polybenzimidazole for high performance fibers.
    Type: Grant
    Filed: December 10, 2009
    Date of Patent: April 30, 2013
    Assignee: E I du Pont de Nemours and Company
    Inventors: Joachim C. Ritter, Rajiv Dhawan
  • Process for the preparation of highly pure monomers for polybenzimidazole materials
    Patent number: 8420862
    Abstract: Highly pure 2,3,5,6-tetraaminotoluene species are produced by chemically reducing undesirable oxidation byproducts. The 2,3,5,6-tetraaminotoluene species are then used in the manufacture of superior high-performance polybenzimidazole polymers.
    Type: Grant
    Filed: December 10, 2009
    Date of Patent: April 16, 2013
    Assignee: E I du Pont de Nemours and Company
    Inventors: Rajiv Dhawan, Joachim C. Ritter
  • Integrated process for the preparation of polybenzimidazole precursors
    Patent number: 8404898
    Abstract: An integrated process is provided for preparing 2,3,5,6-tetraminotoluene and salts thereof starting with nitration of 2,6-dihalotoluene. The process design eliminates costly intermediate drying and recrystallization steps. Handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
    Type: Grant
    Filed: December 10, 2009
    Date of Patent: March 26, 2013
    Assignee: E I du Pont de Nemours and Company
    Inventors: Joachim C. Ritter, Rajiv Dhawan
  • 2,4,5-TRIAMINOPHENOLS AND RELATED COMPOUNDS
    Publication number: 20130053573
    Abstract: New triaminophenol compositions and related compounds are disclosed, as are processes for their preparation and for the preparation of novel salts and diacid complexes from such compounds. Polymers prepared from these compositions can be made into high strength fiber, film, and tape and are useful in applications such as protective apparel, aircraft, automotive components, personal electronics, and sports equipment.
    Type: Application
    Filed: December 21, 2010
    Publication date: February 28, 2013
    Applicant: E I DU PONT DE NEMOURS AND COMPANY
    Inventors: Rajiv Dhawan, Joachim C. Ritter
  • INTEGRATED PROCESSES FOR THE PREPARATION OF POLYBENZIMIDAZOLE PRECURSORS
    Publication number: 20130046109
    Abstract: An integrated process is provided for efficiently preparing 2,4,5-triaminaphenol, starting with nitration of 2,6-dihalobenzene; high purity salts thereof; and complexes of 2,4,5-triaminophenol aromatic diacids, which are precursors for making polybenzimidazole polymer for high performance fibers. The process design eliminates several costly intermediate drying and recrystallization steps. The handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
    Type: Application
    Filed: December 21, 2010
    Publication date: February 21, 2013
    Inventors: Rajiv Dhawan, Joachim C. Ritter
  • 2,4,5-TRIAMINOPHENOLS AND RELATED COMPOUNDS
    Publication number: 20130012681
    Abstract: New triaminophenol compositions and related compounds are disclosed, as are processes for their preparation and for the preparation of novel salts and diacid complexes from such compounds. Polymers prepared from these compositions can be made into high strength fiber, film, and tape and are useful in applications such as protective apparel, aircraft, automotive components, personal electronics, and sports equipment.
    Type: Application
    Filed: December 21, 2010
    Publication date: January 10, 2013
    Applicant: E.I. DU PONT DE NEMOURS AND COMPANY
    Inventors: Rajiv Dhawan, Joachim C. Ritter
  • 2,4,5-TRIAMINOPHENOLS AND RELATED COMPOUNDS
    Publication number: 20130012679
    Abstract: New triaminophenol compositions and related compounds are disclosed, as are processes for their preparation and for the preparation of novel salts and diacid complexes from such compounds. Polymers prepared from these compositions can be made into high strength fiber, film, and tape and are useful in applications such as protective apparel, aircraft, automotive components, personal electronics, and sports equipment.
    Type: Application
    Filed: December 21, 2010
    Publication date: January 10, 2013
    Applicant: E I DU PONT DE NEMOURS AND COMPANY
    Inventors: Rajiv Dhawan, Joachim C. Ritter, Frederick K. Mallon, Steven R. Allen, David J. Rodini, Roger K. Siamionko
  • Integrated process for the preparation of polybenzimidazole precursors
    Patent number: 8188316
    Abstract: Processes are provided for preparing complexes of 2,3,5,6-tetraaminotoluene with an aromatic diacid where the aromatic diacid is insoluble in water under ambient conditions. An integrated process design starting with nitration of 2,6-dihalotoluene eliminates costly intermediate drying and recrystallization steps. Handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
    Type: Grant
    Filed: December 10, 2009
    Date of Patent: May 29, 2012
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Rajiv Dhawan, Joachim C. Ritter
  • Integrated process for the preparation of polybenzimidazole precursors
    Patent number: 8188317
    Abstract: An integrated process is provided for preparing complexes of 2,3,5,6-tetraminotoluene with an aromatic diacid starting with nitration of 2,6-dihalotoluene. The process design eliminates costly intermediate drying and recrystallization steps. Handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
    Type: Grant
    Filed: December 10, 2009
    Date of Patent: May 29, 2012
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Rajiv Dhawan, Joachim C. Ritter
  • Process for the preparation of monomers for polybenzimidazole materials
    Patent number: 8163961
    Abstract: Complexes of 2,3,5,6-tetraaminotoluene with an aromatic diacid are prepared by reaction with a divalent salt of the aromatic diacid while maintaining the pH of the reaction solution between 3 and 10. The resulting complexes are suitable for making high molecular weight polybenzimidazole polymers for high-performance fibers.
    Type: Grant
    Filed: February 22, 2010
    Date of Patent: April 24, 2012
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Rajiv Dhawan, Joachim C. Ritter
  • Process for the synthesis of 2,6-diamino-3,5-dinitrotoluene
    Patent number: 8163955
    Abstract: An improved process is provided for the preparation of 2,6-diamino-3,5-dinitrotoluene by amination of 2,6-dichloro-3,5-dinitrotoluene. The presence of water unexpectedly results in a highly pure product, free of glycol ether impurities. This product can be used to make highly pure 2,3,5,6-tetraaminotoluene, which in turn can be used to make high molecular weight polybenzimidazoles for high strength fibers.
    Type: Grant
    Filed: December 10, 2009
    Date of Patent: April 24, 2012
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Rajiv Dhawan, Joachim C. Ritter
  • Integrated process for the preparation of tetraaminobenzene
    Patent number: 8158830
    Abstract: An integrated process is provided for preparing 1,2,4,5-tetraminobenzene and salts thereof, starting in certain embodiments with nitration of 1,3-dihalobenzene. The process design eliminates costly intermediate drying and recrystallization steps. Handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
    Type: Grant
    Filed: December 17, 2008
    Date of Patent: April 17, 2012
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Joachim C. Ritter, Ekaterini Korovessi, Rajiv Dhawan
  • Process for the preparation of derivatives of tetraaminobenzene
    Patent number: 8143450
    Abstract: A process is provided for preparing complexes of 1,2,4,5-tetraminobenzene with an aromatic diacid. The process design eliminates costly intermediate drying and recrystallization steps. Handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
    Type: Grant
    Filed: December 18, 2008
    Date of Patent: March 27, 2012
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Joachim C. Ritter, Ekaterini Korovessi, Rajiv Dhawan
  • Process for the Preparation of Monomers for Polybenzimidazole Materials
    Publication number: 20100160686
    Abstract: A process is provided to produce 2,3,5,6-tetraaminotoluene. Highly pure salts of 2,3,5,6-tetraaminotoluene are produced via reduction of 2,6-diamino-3,5-dinitrotoluene. The 2,3,5,6-tetraaminotoluene salt is precipitated as a clean (>99% purity) product. The salt is a precursor for monomers to make a polybenzimidazole for high performance fibers.
    Type: Application
    Filed: December 10, 2009
    Publication date: June 24, 2010
    Applicant: E. I. DU PONT DE NEMOURS AND COMPANY
    Inventors: JOACHIM C. RITTER, Rajiv Dhawan
  • PROCESS FOR THE SYNTHESIS OF 2,6-DIAMINO-3,5-DINITROTOLUENE
    Publication number: 20100160678
    Abstract: An improved process is provided for the preparation of 2,6-diamino-3,5-dinitrotoluene by amination of 2,6-dichloro-3,5-dinitrotoluene. The presence of water unexpectedly results in a highly pure product, free of glycol ether impurities. This product can be used to make highly pure 2,3,5,6-tetraaminotoluene, which in turn can be used to make high molecular weight polybenzimidazoles for high strength fibers.
    Type: Application
    Filed: December 10, 2009
    Publication date: June 24, 2010
    Applicant: E. I. DU PONT DE NEMOURS AND COMPANY
    Inventors: RAJIV DHAWAN, Joachim C. Ritter
  • INTEGRATED PROCESS FOR THE PREPARATION OF POLYBENZIMIDAZOLE PRECURSORS
    Publication number: 20100160679
    Abstract: Processes are provided for preparing complexes of 2,3,5,6-tetraaminotoluene with an aromatic diacid where the aromatic diacid is insoluble in water under ambient conditions. An integrated process design starting with nitration of 2,6-dihalotoluene eliminates costly intermediate drying and recrystallization steps. Handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
    Type: Application
    Filed: December 10, 2009
    Publication date: June 24, 2010
    Applicant: E. I. DU PONT DE NEMOURS AND COMPANY
    Inventors: Rajiv DHAWAN, Joachim C. RITTER
  • PROCESS FOR THE PREPARATION OF MONOMERS FOR POLYBENZIMIDAZOLE MATERIALS
    Publication number: 20100160676
    Abstract: Complexes of 2,3,5,6-tetraminotoluene with an aromatic diacid are prepared by reaction with a divalent salt of the aromatic diacid while maintaining the pH of the reaction solution between 3 and 10. The resulting complexes are suitable for making high molecular weight polybenzimidazole polymers for high-performance fibers.
    Type: Application
    Filed: February 22, 2010
    Publication date: June 24, 2010
    Applicant: E.I. DU PONT DE NEMOURS AND COMPANY
    Inventors: RAJIV DHAWAN, JOACHIM C. RITTER