Industrial process for the synthesis of 2-substituted 1-(hydroxy-ethylidene)-1,1-bisphosfi- conic acids of high purity and the salts thereof

摘要

Process for the synthesis of high purity 2-substituted-1-(hydroxy-ethylidene)-1,1-bisphosphonic acid of formula (I), the salts and hydrates thereof-wherein the meaning of R is 3'-pyridyl or 2'-amino-ethylidene group-from compounds of formula (II)-wherein the meaning of R is as described above-or salts and hydrates thereof with phosphorous acid in the presence of methanesulfonic acid using phosphorus pentoxide as reagent and in given case the obtained acid is converted into a salt with base.