DISHMAN PHARMACEUTICALS AND CHEMICALS LTD Patent applications |
Patent application number | Title | Published |
20090306429 | PREPARATION OF A QUATERNARY AMMONIUM HYDROXIDE AND USE THEREOF FOR THE PREPARATION OF A QUATERNARY AMMONIUM SALT - 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. Moreover, the process of the invention allows to produce the quaternary ammonium salt from a lignocaine compound in a one-pot synthesis involving mostly water. | 12-10-2009 |
20090187024 | ROPIVACAINE HYDROCHLORIDE ANHYDRATE AND THE PREPARATION THEREOF - 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. | 07-23-2009 |
20080200690 | Preparation of 2-Substituted 4-Chloro-5-Formylimidazole and 5-Formylimidazole - 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. | 08-21-2008 |