Digluconates

Digluconates are chemical compounds in which two gluconate ligands accompany a single divalent metal ion, forming bis(gluconato) salts. The general formula is M(C6H11O7)2, where M represents a divalent cation such as calcium (Ca2+), magnesium (Mg2+), zinc (Zn2+), or copper (Cu2+). The gluconate ligand is the dianion derived from gluconic acid (C6H12O7). Digluconates are encountered mainly as mineral supplements and pharmaceutical ingredients, for example calcium digluconate, zinc digluconate, and magnesium digluconate.

Preparation and structure: They are typically prepared by neutralizing gluconic acid with a metal oxide, hydroxide, or carbonate in a 2:1 metal-to-gluconate ratio, or by metathesis between a soluble metal salt and a gluconate source. The resulting salts are usually water-soluble and may form hydrates. The coordination environment around the metal can influence solubility and bioavailability.

Occurrence and use: In dietary supplements, digluconates supply a metal ion with relatively good solubility and stability. Calcium digluconate is used where calcium delivery is desired; zinc digluconate provides zinc in multivitamin formulations; magnesium digluconate serves as a magnesium source in supplements and medications. They are also employed in pharmaceutical formulations and, in some cases, in fortified foods and beverages.

Properties and safety: Digluconates generally exhibit moderate to high water solubility, with properties dependent on the coordinated metal. As with other metal gluconates, excessive intake can lead to metal-specific adverse effects, and regulatory limits apply for foods and supplements. Medical and injection uses require appropriate clinical guidance.

See also: gluconate, gluconic acid, calcium digluconate, zinc digluconate.