Ferric ammonium citrate prepn - from calcium citrate, ferric sulphate and ammonia

摘要

Process comprises reacting ferric sulphate with calcium citrate, removing CaSO4 and treating the product with ammonia. As a medicament and in photography. The process uses materials of known purity and the intermediates are easily isolated. pH of the mixt. is adjusted to pH 4-6 before removal of CaSO4 and after removal is adjusted further to pH 7.2-7.5. A stoichiometric excess of calcium citrate is used. 200g. calcium citrate added to a filtered soln. of 200g. ferric sulphate in 500 cc. water at 70 degrees C stirred at 50-70 degrees C, 75 cc. NH3 added to pH 4.5 air bubbled through for 2 hrs., a further 10 cc. NH3 added to pH. 6.0, the mixt. filtered, the ppt. washed with water at room temp. NH3 added to the filtrate to pH 7.4 and the soln. concd. gave pure ferric ammonium citrate, Fe(NH3)2(C6H5O7)3H2O.