Method for the preparation of isosorbide-5-nitrate and sodium isosorbide-5-nitrate hydrate as a precursor thereof

摘要

A novel and efficient method is proposed for the preparation of isosorbide-5-nitrate which is a promising medicinal compound for several diseases due to disorder in heart. The method comprises direct nitration of isosorbide with a concentrated nitric acid in a specific reaction medium containing an aromatic hydrocarbon solvent, e.g. benzene, in addition to conventional acetic acid and acetic anhydride. After neutralization of the reaction mixture and removal of the dinitrate as a byproduct therefrom, the reaction mixture is admixed with an aqueous solution of sodium hydroxide so that a sodium salt of isosorbide-5-nitrate is precipitated in the form of a hydrate, which is a novel compound not known in the prior art. This hydrate sodium salt is then decomposed with an acid to give the desired isosorbide-5-nitrate in a high yield.