Method to purify tris-(3-hydroxybutyrato)-glyceryl ester

A method of purifying a compound of formula (I)

• as a single enantiomer or as a mixture of isomers, comprising:
• a. one or more washes of an aqueous solution of a compound of formula (I) and wherein the aqueous solution comprises NaCl from 0% to 5% w/w, with an organic solvent S1;
• b. increase of the concentration of NaCl of the aqueous solution of a compound of formula (I) as in point a. greater than 5% w/w;
• c. one or more extractions of the aqueous solution of a compound of formula (I) as in point b. with an organic solvent S2, and
• d. concentration of the solution of a compound of formula (I) in an organic solvent S2 to obtain a compound of formula (I),
• and wherein the solvent S1 is an organic solvent selected from a cyclic or acyclic ether or a non-polar aprotic solvent, and wherein the solvent S2 is an organic solvent selected from a polar aprotic solvent;
• a chlorinated solvent;
• an ester;
• or a linear or branched C3-C7 ketone.