Patents Assigned to DISHMAN PHARMACEUTICALS AND CHEMICALS LTD
  • Publication number: 20090306429
    Abstract: The invention relates to a process for the preparation of a quaternary ammonium hydroxide, in particular denatonium hydroxide, and the use thereof for the preparation of a quaternary ammonium salt, in particular of denatonium benzoate or a denatonium fatty acid derivative. Due to its extremely bitter taste, this latter compound is applied in the art as an aversive agent, biocide, antifoulant and flavorant. It is usually prepared from a quaternary ammonium halide in an organic environment, which after isolation and purification is converted to a hygroscopic and unstable hydroxide intermediate, which in turn is immediately converted to the salt of interest in the solvent in which it is prepared. It is now found that these isolation steps can be avoided by performing the reaction at aqueous conditions. This is more straightforwardly and does not require costly precautions to avoid contact while handling.
    Type: Application
    Filed: November 30, 2005
    Publication date: December 10, 2009
    Applicants: DISHMAN PHARMACEUTICALS AND CHEMICALS LTD
    Inventors: Rajnikant Vyas Janmejay, Jayshree H. Shah, Ravindra Niranjanbhai Raval
  • Publication number: 20090187024
    Abstract: The invention pertains to a process for preparing stable anhydrous Ropivacaine hydrochloride, the process involving preparing Ropivacaine hydrochloride from Ropivacaine base, wherein Ropivacaine base is provided having a chiral purity of more than 95%, and wherein the isolation involves the use of isopropanol and hydrochloride, and is performed under water-free conditions. Ropivacaine base may be provided at high chiral purity by N-propylating L-pipecolic acid 2,6-xylidide hydrochloride in the presence of a phase transfer catalyst, wherein the reaction involves a biphasic reaction mixture containing an alkaline aqueous phase and an organic phase. The invention further pertains to stable anhydrous Ropivacaine hydrochloride obtainable by the above process.
    Type: Application
    Filed: April 25, 2007
    Publication date: July 23, 2009
    Applicant: DISHMAN PHARMACEUTICALS AND CHEMICALS LTD.
    Inventors: Janmejay Rajnikant Vyas, Venkata Satya Varma Nidadavolu, Denish Hasmukhlal Shah
  • Publication number: 20080200690
    Abstract: The invention relates to a preparation process for 2-substituted 5-formylimidazoles, wherein the intermediate high-pressurized synthesis of an 2-substituted 4-hydroxymethylimidazole as known in the art is conveniently avoided, and wherein much higher yields are obtained. Instead, it is proposed to prepare such 2-substituted 5-formylimidazoles via a one-pot synthesis involving 2-substituted 4-chloro-5-formylimidazole, thereby employing an additional hydrodehalogenation step. Moreover, it is found that the yield and purity of 2-substituted 4-chloro-5-formylimidazole itself can be significantly improved using a triflate catalyst in the preparation process.
    Type: Application
    Filed: April 7, 2006
    Publication date: August 21, 2008
    Applicants: DISHMAN PHARMACEUTICALS AND CHEMICALS LTD, Henk Plum
    Inventors: Janmejay Rajnikant Vyas, Venkata Satya Varma Nidadavolu, Anand Praksh Singh