Magnesium stearate
| Chemical formula | C36H70MgO4 |
| Molar mass | 591.24 g/mol |
| CAS number | 557-04-0 |
| RTECS | WI4390000 |
| EC | 209-105-3 |
| HS | 38249993 |
| Storage | 5 to + 30 C |
| Odour | odourless |
| Form | solid |
| Color | white |
| Melting point | 140 ° C |
| Description | Conforms | ||
| Solubility | Conforms | ||
| Identification | Conforms | ||
| LOD | ≤ | 6 | % |
| Acidity & alkalinity | ≤ | 0.05 | ml |
| Heavy metals (lead) | ≤ | 0/001 | % |
| Chloride | ≤ | 0/1 | % |
| Sulfate | ≤ | 1 | % |
| Palmitic & Stearic acid components of fatty acid | ≥ | 90 | % |
| Stearic acid components of fatty acid | ≥ | 40 | % |
| Assay (Mg) | 4.0 – 5.0 | % |
Magnesium stearate is a fine, white, powdery substance that is widely used as a lubricant and anti-caking agent in pharmaceuticals, food products, and cosmetics. It is a magnesium salt of stearic acid and is known for its hydrophobic properties and low reactivity.
🏭⚗️ Production
Magnesium stearate is produced by the reaction of magnesium salts (commonly magnesium sulfate or magnesium chloride) with sodium stearate or directly with stearic acid in the presence of a base. The product is then filtered, washed, and dried to yield a fine, odorless powder with consistent physical properties. It is manufactured under controlled conditions to meet food-grade or pharmaceutical-grade standards.
🔬 Properties
The chemical formula of magnesium stearate is Mg(C₁₈H₃₅O₂)₂, with a molar mass of approximately 591.24 g/mol. It appears as a white, soft, water-insoluble powder. It is insoluble in water, alcohol, and ether, but soluble in hot ethanol. Magnesium stearate is thermally stable and has a melting point around 130–150 °C. It is hydrophobic and exhibits good lubricating and flow-enhancing properties in powder mixtures.
🧪 Applications
Magnesium stearate is widely used in the pharmaceutical industry as a tablet and capsule lubricant, aiding in the efficient manufacturing of solid dosage forms. In the food industry, it serves as an anti-caking agent and release agent (food additive E470b). It is also used in cosmetics, where it contributes to texture and consistency in powders and creams. Additionally, it finds application in plastics and rubber as a processing aid.
⚠️ Safety
Magnesium stearate is generally recognized as safe for use in food and pharmaceuticals at approved levels. It is non-toxic and non-irritating under normal handling conditions. However, inhalation of airborne powder should be minimized, as excessive dust may cause mild respiratory irritation. Standard protective measures, such as gloves and masks, are recommended during industrial handling. It should be stored in a dry place away from strong oxidizing agents.
