Process for the preparation of sevelamer

Abstract

The present invention relates to a process for the preparation of sevelamer, in particular sevelamer hydrochloride and sevelamer carbonate/bicarbonate, by means of a process that allows sevelamer to be obtained with good yields and using conventional reactors, without requiring to use specific and expensive equipment.

1 . A process for the preparation of sevelamer characterized in that it comprises the following steps:
 (a) partially salifying a polyallylamine aqueous solution having a concentration between 10% and 14.5% (w/w);   (b) adding epichlorohydrin;   (c) maintaining the reaction mixture under stirring;   (d) isolating the sevelamer thus obtained;   and also characterized in that the steps from (a) to (c) are carried out in the absence of any organic solvents.   
     
     
         2 . The process according to  claim 1 , characterized in that the polyallylamine is salified up to a degree of salification of 25-40%. 
     
     
         3 . The process according to  claim 1 , characterized in that the “allylamine unit”/“epichlorohydrin” molar ratio is around 8-11/1. 
     
     
         4 . The process according to  claim 1 , characterized in that in the step (c) it is maintained under stirring at 65 and 85° C. for a few hours. 
     
     
         5 . The process according to  claim 1 , characterized in that said polyallylamine aqueous solution has a concentration between 12.5 and 14.5%. 
     
     
         6 . The process according to  claim 5 , characterized in that said polyallylamine aqueous solution has a concentration between 13 and 14%. 
     
     
         7 . The process according to  claim 1 , characterized in that polyallylamine is partially salified with hydrochloric acid. 
     
     
         8 . Sevelamer obtained with the process of  claim 6  characterized in that it has the following properties: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Chlorides % (weight/weight) 
                   17-19 
                 
                     
                   Swell index 
                   12-13 
                 
                     
                   Phosphate binding capacity (mmol/g) 
                   5.5-6.4 
                 
                     
                   Epichlorohydrin 
                   <5 ppm 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
       
     
     
         9 . The process according to  claim 1 , characterized in that the sevelamer thus obtained is converted into sevelamer carbonate/bicarbonate. 
     
     
         10 . The process according to  claim 9 , characterized in that the sevelamer thus obtained is converted into sevelamer carbonate/bicarbonate by reaction with gaseous CO2. 
     
     
         11 . The process according to  claim 9 , characterized in that the conversion into sevelamer carbonate/bicarbonate with gaseous CO2 is carried out in solid phase.