How to Synthesise High Purity, Crystalline d-Glucaric Acid Selectively.

Glucaric acid has potential applications in food, pharmaceutical and polymer industries yet no methodology exists within the public domain for isolation of this key bio-derived platform molecule as a pure, crystalline solid. Here we demonstrate the difficulties, which arise in doing so and report development of a process for derivation of free-glucaric acid from its Ca2+/K+ glucarate salts, which are both commercially available. Employing Amberlyst-15 (H+) exchange resin and azeotrope drying, powdered glucaric acid is prepared at > 99.96 % purity in 98.7 % dry yield.