Iron Gluconate, Ferrous Gluconate, E579, 299-29-6, 22830-45-1

Iron Gluconate, Ferrous Gluconate, E579, 299-29-6, 22830-45-1

1. General Overview and Definition

Iron(II) Gluconate is the iron salt of gluconic acid. It is a coordination complex and a popular mineral supplement used to treat or prevent iron deficiency. Its significance lies in its role as a source of ferrous ions (Fe²⁺), which are essential for human biology.

• Chemical Name: Iron(II) Gluconate or Ferrous Gluconate

• Molecular Formula: The correct formula is typically C₁₂H₂₂FeO₁₄ (anhydrous) or C₁₂H₂₂FeO₁₄ · 2H₂O (dihydrate). (Note: The formula you provided, C12H24FeO1, appears to have a typo; the correct structure contains 14 oxygen atoms.)

• CAS Number: 299-29-6 (Anhydrous), 22830-45-1 (Dihydrate)

• Molecular Weight: 448.16 g/mol (for the dihydrate form; the anhydrous form is approximately 446.14 g/mol).

• Other Names: Ferro Glucon, Ferrous Gluconate, Iron Bis(D-Gluconato), Pentahydroxyhexanoate.

2. Production Methods

As you noted, there are two primary industrial methods for synthesizing Ferrous Gluconate:

A. Barium Gluconate and Iron(II) Sulfate Reaction (Double Displacement)
This is the most common method.

• Process: Barium Gluconate is reacted with Iron(II) Sulfate in an aqueous solution.

• Reaction: Ba(C6H11O7)2 + FeSO4 → Fe(C6H11O7)2 + BaSO4↓

• Explanation: When these two solutions are mixed, a double displacement reaction occurs. Barium Sulfate (BaSO4), which is highly insoluble in water, precipitates out as a white solid. The desired product, Ferrous Gluconate, remains dissolved in the solution. The Barium Sulfate is removed via filtration, and the remaining liquid is evaporated and crystallized to yield pure Ferrous Gluconate crystals.

• Caution: Because barium salts are toxic, the process must be carefully controlled to ensure no barium residue remains in the final product.

B. Iron Carbonate and Gluconic Acid Reaction (Acid-Base Reaction)
This method is often preferred for producing a very pure product.

• Process: Aqueous Iron(II) Carbonate is reacted with Gluconic Acid.

• Reaction: FeCO3 (slurry) + 2 C6H12O7 (Gluconic Acid) → Fe(C6H11O7)2 + CO2↑ + H2O

• Explanation: Gluconic acid is added to a suspension of Iron(II) Carbonate and heated. The acid reacts with the carbonate to release Carbon Dioxide gas (effervescence) and form the iron salt. Once the reaction is complete and gas evolution stops, the solution is purified and crystallized.

3. Physical and Chemical Properties

A. Appearance and Color

• Physical State: Yellowish-gray or greenish-yellow fine powder or granules.

• Color & pH Relationship: The color of a Ferrous Gluconate solution is highly dependent on pH, which indicates the stability of the iron ion.

  • Low pH (Acidic): The solution is pale yellow or light green. This is the characteristic color of the ferrous iron (Fe²⁺) ion.

  • pH 4.5: The color shifts to brown. This indicates oxidation; the ferrous iron (Fe²⁺) is starting to convert to ferric iron (Fe³⁺), forming brown iron hydroxides.

  • Neutral pH (pH 7): The solution turns green. At this pH, ferrous ions are very unstable and will rapidly oxidize in air, turning brown.

B. Thermal and Physical Constants

• Melting Point: Approximately 188 °C (370 °F). At this temperature, it usually decomposes rather than melting cleanly.

• Density: ~2.1 g/cm³ (at 20 °C).

• Boiling Point: Not applicable (decomposes before boiling).

C. Solubility

• Water: Solubility is about 119 g/L at room temperature (approx. 20°C). It is more soluble in hot water.

• Organic Solvents: It is insoluble in Ethyl Alcohol (Ethanol) and ether. This property is useful for purification.

• Enhancing Solubility: The solubility and stability of ferrous gluconate can be improved by adding Citric Acid or Trisodium Citrate. These agents act as chelators, binding to the iron and preventing it from oxidizing or precipitating.

4. Applications and Uses

Ferrous Gluconate is valued for its high bioavailability and relatively mild effect on the stomach compared to other iron salts (like ferrous sulfate).

A. Medical and Pharmaceutical Sector (Primary Use)

• Treatment of Iron Deficiency Anemia: Iron is a core component of hemoglobin, the protein in red blood cells that carries oxygen. When iron levels are low, the body cannot produce enough healthy red blood cells. Ferrous Gluconate is prescribed to replenish iron stores.

• Formation of Ferritin: The body stores excess iron in the bone marrow, liver, and spleen in a protein complex called Ferritin. Ferrous Gluconate helps build and maintain these iron reserves.

• Multivitamin Supplements: It is the preferred iron source in many multivitamin tablets and liquid tonics because it causes less gastrointestinal irritation (constipation, nausea) than other forms. It is often prescribed by doctors for this reason.

• Pregnancy: It is commonly recommended during pregnancy to meet the increased iron demands of both the mother and the developing fetus.

B. Food Industry

• Food Fortification: It is used to enrich foods with iron to prevent dietary deficiencies.

  • Breakfast Cereals: Added to processed cereals to replace iron lost during milling.

  • Infant Formulas: Essential for the rapid growth and development of babies.

  • Soy and Corn Products: These foods contain phytates that can inhibit iron absorption, but chelated forms like gluconate are less affected.

• Olive Processing (Blackening): As you mentioned, it is used in the production of "artificially blackened" olives. Green olives are cured in a ferrous gluconate solution. The iron reacts with natural polyphenols in the olive skin to create a stable, uniform black color.

5. Importance in Human Biology

Iron is a trace element of immense importance in the human body:

• Oxygen Transport: It is the central atom in the heme group of hemoglobin (red blood cells) and myoglobin (muscle cells).

• Enzyme Cofactor: Iron acts as a component or cofactor for many essential enzymes involved in energy production (cytochromes in the electron transport chain), DNA synthesis, and detoxification processes in the liver.

Summary

Iron(II) Gluconate is a vital coordination compound bridging the gap between inorganic chemistry and human health. It is produced via specific chemical reactions (like the Barium Sulfate precipitation method) and is characterized by its pH-sensitive color and moderate water solubility. Its primary value lies in its role as a gentle, effective dietary supplement for combating iron deficiency anemia, fortifying foods, and even in the food coloring of olives. Its ability to provide bioavailable iron with fewer side effects makes it a staple in medicine cabinets and food processing plants worldwide.

Other Names and Synonyms for Iron(II) Gluconate

Iron(II) Gluconate is known by many different names depending on the context: chemical literature, pharmaceutical marketing, food labeling, or industrial production.

1. Chemical Names (IUPAC & Systematic Nomenclature)

These are the formal names used by chemists to describe the exact molecular structure.

• Ferrous Gluconate: The most common pharmaceutical and general name.

• Iron(2+) Gluconate: The modern IUPAC (International Union of Pure and Applied Chemistry) designation.

• Iron(II) Gluconate: Specifies the oxidation state of the iron (+2), distinguishing it from Ferric (Iron III) compounds.

• Iron, Bis(D-Gluconato)-: The name as indexed in chemical registries like Chemical Abstracts.

• Bis(D-gluconato)iron: Describes the molecule as a complex where two gluconate ions are bound to a central iron atom.

• Pentahydroxyhexanoate iron: A descriptive name based on the gluconate part (a hexanoic acid with five hydroxy groups).

• D-Glucaric acid, iron(2+) salt: A less common, older systematic name.

2. Brand Names & Proprietary Names

These are the names used by pharmaceutical companies when selling the supplement.

• Ferro Glukon: (As mentioned in your list) A common trade name variant in European and Turkish markets.

• Fergon: One of the oldest and most well-known brand names for Ferrous Gluconate (historically marketed by Bayer).

• Ferralet: Another brand name used for iron supplement tablets.

• Simron: A former brand name for iron capsules.

• Iron Gluconate: The generic name used on store shelves.

3. Registry Codes & Identifiers

These are not spoken "names," but they are unique alphanumeric codes used to identify the substance in databases.

• CAS Number: 299-29-6: The unique identifier assigned by the Chemical Abstracts Service for the anhydrous (dry) form.

• CAS Number: 22830-45-1: The unique identifier specifically for the Dihydrate form (contains two water molecules).

• UNII: U5X7F30P1W: A non-proprietary unique identifier assigned by the FDA (US Food & Drug Administration) for substances in drugs and foods.

• E Number: E579: The code used in the European Union for food additives. This is the number you might see on food labels (e.g., for black olives).

4. Hydrate Forms (Crystal Structures)

Because iron gluconate often crystallizes with water molecules, it is referred to by these names to specify the hydration state:

• Dihydrate Form: The most common commercial form. It contains two molecules of water of hydration. (Formula: C₁₂H₂₂FeO₁₄·2H₂O).

• Anhydrous Form: The form without any water molecules.

• Ferrous Gluconate Dihydrate: The full name of the common hydrated version.

5. Multilingual Synonyms

• Glukonsaures Eisen(II): German.

• Gluconate de Fer: French.

• Gluconato Ferroso: Spanish/Italian.

• Ferrum Gluconicum: Latin / Old Pharmacopoeia name.

6. Descriptive Synonyms

• Iron Sugar: An informal, colloquial term sometimes used because gluconate is derived from glucose (sugar).

• Pentahydroxyhexanoyloxyiron: The expanded chemical name you listed, describing the ester-like linkage.

Summary for Quick Reference:

• If you are in a pharmacy or hospital, look for Ferrous Gluconate.

• If you are looking at a food label (especially on olives), look for E579.

• If you are looking for the scientific data sheet, search for CAS 299-29-6.

• If you are buying the raw chemical, it is often sold as Iron(II) Gluconate Dihydrate.