Abstract: This article is about study on synthesis of sodium etidronate . In the past , two-steps method was used. First , 1 - hydroxyethylidene -1,1- diphosphonic acid was preparated , then turned to sodium salt after recrystallizating with glacial acetic acid . And now the two-steps method of Synthesis of Sodium Etidronate is improved that the 1 - hydroxyethylidene -1,1- diphosphonic acid without recrystallizating but directly turned into salt . Water was added for diluting firstly, then 40% of sodium hydroxide was added for raising the pH value to 4.5 , at last three times’ volume of ethanol was plused to precipitate and get the Sodium Etidronate . It investigated the quality of products and yield by using different ratio of raw materials , different reaction temperature , different water usage and different volume of ethanol . Using single factor test , the result enunciate that the most suitable and proper reaction conditions is that: acetic acid and phosphorus trichloride’s molar ratio is 1:3 , the reaction temperature is 110℃ , the water usage is one time and the volume of ethanol is three times . This method not only omitted the step of recrystallization of 1 - hydroxyethylidene -1,1- diphosphonic acid, but also simplified the production process and operation . The quality of products and yield were improved , and equipment and raw materials investment were saved .
Keywords：Sodium Etidronate ; 1-hydroxy-ethylene-1,1diphosporic acid ; the quality of products and yield
