Introduction of Magnesium Stearate

Jan 12,2022

General description

Magnesium distearate is a magnesium salt. Magnesium stearate is a white, dry, easy, sand free and smooth powder, non-toxic, The chemical structure formula is Mg (C18H35O2) 2. The molecular weight is 591.25. It contains 4.11% magnesium, 95.90% stearic acid and more than 99.5% purity. Melting point: 88.5 ℃. It is insoluble in water and decomposes with strong acid. Magnesium stearate, with chemical formula of c36h70mgo4 and molecular weight of 591.24, is an organic compound. It is a white sand free fine powder and feels greasy in contact with skin. Insoluble in water, ethanol or ether, it is mainly used as lubricant, anti adhesion agent and flow aid. It is especially suitable for granulating oil and extract drugs. The particles have good fluidity and compressibility. It is used as a flow aid in direct tablet pressing. It can also be used as filter aid, clarifier and defoamer, as well as suspension aid and thickener of liquid preparations.

Application and pharmacology

It is widely used in pharmaceutical industry and gastric antacid. The product quality reaches "magnesium stearate" in Pharmacopoeia of the people's Republic of China, 2000 edition Quality standards and hygienic standards for the use of food additives are mainly used for food molding agents, emulsifiers, anti caking agents and tablet release agents. Paint driers. Perfume powder, cosmetics, paint, coating desiccant, transparent smoothing agent. Excellent lubricating, dispersing and stabilizing additives for plastics and rubber. Used in bakelite to make lubrication bright and transparent. 

1.Magnesium stearate (MgSt) is a widely used pharmaceutical lubricant in tablet manufacturing. However, batch-to-batch variability in hydrate form and surface area can lead to inconsistency in tablet performance. In this work, several unique MgSt samples were studied: traditional monohydrate samples with high surface area, dihydrate forms with high and low surface area, and disordered forms with low and medium water content. The effects of solid-state form and particle properties on lubrication efficiency, tabletability and dissolution were studied for tablets in a model direct compression formulation. It was found that the monohydrate and dihydrate forms had good lubrication efficiency compared to the disordered form, while the disordered form had the best tabletability. The dissolution rate correlated with surface area, where slower dissolution rates corresponded with higher MgSt surface areas. The dihydrate sample with lower surface area had the best performance for this model formulation, in terms of lubrication efficiency, tabletability and dissolution. Overall, it is concluded that the choice of the most appropriate grade of MgSt for a particular formulation depends on a comprehensive evaluation of the impact of MgSt properties on lubrication efficiency, tabletability and dissolution.

2.Separation of an oil/water mixture has become a very attractive subject due to frequent oil spill incidents and industrial oily wastewater treatment. In this study, a robust superhydrophobic/superoleophilic polyurethane sponge comprising magnesium stearate nanoparticles coating and phenol-formaldehyde resin was developed by the cost-effective immersion method for the removal of organic materials and oil from the oil/water system. The characterizations of the modified polyurethane by SEM, FESEM, FTIR, Raman and EDX confirmed that it was well coated with phenol-formaldehyde and magnesium stearate nanoparticles. The water contact angle measurement results showed a contact angle exceeding 175° and siliding angle less than 3°, which are, compared to other reports up to now, a great unprecedented achievement. Also, no considerable change after abrasing and immersing in the acidic and basic solution was observed. Due to outstanding water contact angle, the organic absorption time is less than 1 second, covering a wide absorption capacity range of 29-38 g/g depending on the viscosity and density of oils. Finally, the modified polyurethane sponge provided an excellent performance capability of the continuous oil/water separation, required for an industrial application.[1,2]


Synthetic magnesium stearate is made of stearic acid and Magnesium Oxide (magnesium hydroxide) at room temperature (18~30 degrees) by one-step method, room temperature synthesis of magnesium stearate, magnesium stearate is powder (high temperature synthesis magnesium stearate is wax body, magnesium stearate is smashed to micron scale is very difficult), grinding can be micron scale. Magnesium stearate can be made of magnesium stearate emulsion of 50%, 40% and 30% before drying.

Figure the systhesis route of magnesium stearate

By a specific process, high quality magnesium stearate with good color and luster was cleanly synthesized by the direct reaction of basic magnesium carbanate with stearic acid in aqueous medium under atmospheric pressure without any additive.It was shown that the rate of the synthetic reaction was affected obviously by the reaction temperature and liquid-solid ratio of the feed, and the first rate product of magnesium stearate could be synthesized under the following conditions :reaction temperature is 80 ℃, liquid-solid ratio of the feed is 6 ∶1, and reaction time is 300 min .Compared with that of traditional technology of double decomposition method, the productivity of this technology was raised and the consumption of energy and water reduced greatly .Since this process can make use of the production equipment in the double decomposition process, it can be adopted by the existing enterprises that originally using the double decomposition process to produce magnesium stearate to restructure in an environmentally friendly way.[3]


1., "Magnesium Stearate Nanoparticle– Coated Superhydrophobic,".

2.EJ Munson J. L., Paul S. & Yanez E. G. et al., "The impact of solid-state form, water content and surface area of magnesium stearate on lubrication efficiency, tabletability, and dissolution," Pharmaceutical development and technology, Vol.26, No.2(2021), pp.150-156.

3.Wu Maoying and Luo Yongxin: Clean Synthesis of magnesium stearate by direct method in atmospheric pressure aqueous medium, chemical industry and engineering, 2008, No. 03, pp. 212-214.

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