Fig. 1.

Chemical structures of d-3HB acid (A) and different forms of ketone supplements (B–E) including ketone salts and esters. (R)-3-hydroxybutyly (R)-3-hydroxybutyrate is synthesized via a transesterification reaction between 1,3-butanediol and ethyl-3-hydroxybutyrate. Bis-hexanoyl (R)-1,3-butanediol is a newly-synthesized ketone ester which can be hydrolyzed into hexanoic acid and 1,3-butanediol. E shows a ketone diester derived from acetoacetate. All structures are redrawn using ChemDraw Professional as original artworks