Salts of carnitine derivatives and methods of production

Abstract

Disclosed are salts, such as nitrates, of acetyl-L-carnitine and propionyl-L-carnitine and methods of making the compounds.

1 . A compound comprising the chemical formula of: 
       
         
           
           
               
               
           
         
         wherein R is selected from the group consisting of: acetyl group and propionyl group. 
       
     
     
         2 . The compound of  claim 1 , wherein the compound is acetyl-L-carnitine nitrate. 
     
     
         3 . The compound of  claim 1 , wherein the compound is propionyl-L-carnitine nitrate. 
     
     
         4 . A method of producing acetyl-L-carnitine nitrate comprising:
 producing acetyl-L-carnitine free base, comprising the steps of:
 adding L-carnitine and acetic acid into a reactor, wherein the L-carnitine is dissolved by acetic acid; 
 adding acetic anhydride into the reactor after L-carnitine is dissolved, wherein the reaction between acetic anhydride and L-carnitine is allowed to react for 3-12 hours at 30° C. to 80° C.; 
 distilling the contents of the reactor at reduced pressure, wherein acetic acid produced from the reaction of acetic anhydride and L-carnitine is distilled away before adding stirring in acetone into the reactor; 
 crystallizing the contents of the reactor at a temperature of less than 5° C., wherein the reactor is maintained at between 0° C. and 5° C. for at least two hours; and 
 filtering the crystallized contents of the reactor before drying the contents to isolate acetyl-L-carnitine free base crystal; and 
   producing acetyl-L-carnitine nitrate from the isolated acetyl-L-carnitine free base crystal, comprising the steps of:
 dissolving the isolated acetyl-L-carnitine free base crystal with acetic acid; 
 reacting nitric acid with the dissolved acetyl-L-carnitine free base for 2-5 hours at between 30° C. to 80° C.; 
 distilling the products of the reaction between nitric acid and acetyl-L-carnitine free base at reduced pressure, wherein the acetic acid and water produced from the reaction are distilled away before stirring acetone into the remaining products of the reaction; 
 crystallizing the remaining products of the reaction at a temperature of less than 5° C., wherein the remaining products are maintained at between 0° C. and 5° C. for at least two hours; and 
 filtering the crystallized products of the reaction before drying to isolate acetyl-L-carnitine nitrate crystal. 
   
     
     
         5 . The method of  claim 4 , wherein producing acetyl-L-carnitine free base comprises using 0.65 g to 3 g of acetic acid for every gram of L-carnitine. 
     
     
         6 . The method of  claim 4 , wherein producing acetyl-L-carnitine nitrate comprises using 0.8 g to 3 g of acetic acid for every gram acetyl-L-carnitine. 
     
     
         7 . The method of  claim 4 , wherein producing acetyl-L-carnitine free base comprises using 1-3 moles of acetic anhydride for every mole of L-carnitine. 
     
     
         8 . The method of  claim 4 , wherein producing acetyl-L-carnitine nitrate comprises using 1-1.5 moles of acetic anhydride for every mole of acetyl-L-carnitine free base. 
     
     
         9 . The method of  claim 4 , wherein producing acetyl-L-carnitine free base comprises using an amount of acetone by weight that is two to five times the weight of L-carnitine. 
     
     
         10 . The method of  claim 4 , wherein producing acetyl-L-carnitine nitrate comprises using an amount of acetone by weight that is two to five times the weight of acetyl-L-carnitine free base.