Magnesium chloride
[CAS# 7786-30-3]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal halides and halides >> Metal chlorides and salts
• Name: Magnesium chloride
• Molecular Formula: MgCl₂
• Molecular Weight: 95.21
• CAS Registry Number: 7786-30-3
• EC Number: 232-094-6
• SMILES: [Mg+2].[Cl-].[Cl-]

Properties

• Density: 2.32 g/mL (Expl.)
• Melting point: 714 °C (Expl.)
• Boiling point: 1412 °C (Expl.)
• Solubility: water 55% w/w (20 $degreeC), very soluble in ethonol (Expl.)

Safety Data

• Hazard Symbols: GHS05;GHS07 Danger
• Risk Statements: H290-H302-H315-H318-H319-H335
• Safety Statements: P234-P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P305+P354+P338-P317-P319-P321-P330-P332+P317-P337+P317-P362+P364-P390-P403+P233-P405-P406-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Serious eye damage	Eye Dam.	1	H318
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin sensitization	Skin Sens.	1	H317
Skin corrosion	Skin Corr.	1	H314
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

Magnesium chloride is an inorganic salt with the chemical formula MgCl₂. It occurs naturally in various hydrated forms, with the hexahydrate (MgCl₂·6H₂O) being the most common. This compound is highly soluble in water and exists as colorless, deliquescent crystals or as a white powder. Magnesium chloride is widely used in industrial, agricultural, and medical applications due to its chemical reactivity, solubility, and physiological compatibility.

Magnesium chloride is primarily obtained from natural sources such as seawater, salt lakes, and brine wells. One of the richest sources is the Dead Sea, where it is extracted along with other salts. Another important source is the mineral bischofite (MgCl₂·6H₂O), which occurs in ancient seabed deposits. Industrial production typically involves the concentration of magnesium-rich brines, followed by crystallization and purification steps. In anhydrous form, magnesium chloride can also be prepared by the reaction of magnesium oxide or magnesium carbonate with hydrochloric acid.

One of the key industrial uses of magnesium chloride is in the production of magnesium metal. In this process, anhydrous MgCl₂ is electrolyzed in a molten state to yield magnesium metal and chlorine gas. This method, known as the Dow process, has been widely used for commercial magnesium production. The high reactivity of magnesium and its light weight make it valuable in aerospace, automotive, and structural applications.

Magnesium chloride is also used as a fluxing agent in the production of ceramics, textiles, and cement. In the construction industry, it is added to magnesium oxychloride cement, sometimes referred to as Sorel cement, which is known for its fast setting, hardness, and abrasion resistance. This type of cement is used in flooring, fire-resistant panels, and polishing stones.

In agriculture, magnesium chloride serves as a source of magnesium, an essential plant nutrient involved in chlorophyll synthesis and enzymatic functions. It is used to correct magnesium deficiency in soils, often in the form of a foliar spray or soil amendment. In livestock farming, magnesium chloride is added to feed and water to prevent hypomagnesemia, commonly known as grass tetany, in grazing animals.

Another important application is in road maintenance, where magnesium chloride is used as a de-icing agent and dust suppressant. It lowers the freezing point of water, helping to prevent the formation of ice on roads during winter. It also binds fine dust particles in unpaved roads, reducing airborne dust and improving visibility and air quality.

In the medical field, magnesium chloride is administered orally or intravenously to treat magnesium deficiency in humans. It has been used in managing electrolyte imbalances, cardiac arrhythmias, and preeclampsia. Due to its good bioavailability, it is often preferred in nutritional supplements. Solutions of magnesium chloride are also used in certain topical applications to soothe sore muscles and joints.

Magnesium chloride is generally recognized as safe when used according to recommended guidelines. However, excessive exposure or ingestion can lead to gastrointestinal discomfort or hypermagnesemia, particularly in individuals with impaired kidney function. In industrial settings, handling precautions include the use of protective equipment to prevent skin and eye contact with concentrated solutions or dust.

In summary, magnesium chloride is a versatile and widely used inorganic compound with applications in metallurgy, agriculture, construction, road safety, and medicine. Its natural abundance, solubility, and chemical reactivity support its continued importance in both industrial processes and public health.

References

2024. Characterization and Performance Evaluation of Magnesium Chloride-Enriched Polyurethane Nanofiber Patches for Wound Dressings. International Journal of Nanomedicine, 19.
DOI: 10.2147/ijn.s460921

2024. Unraveling the Mechanisms Involved in the Beneficial Effects of Magnesium Treatment on Skin Wound Healing. International Journal of Molecular Sciences, 25(9).
DOI: 10.3390/ijms25094994

1984. Magnesium absorption in mature ewes infused intrarumenally with magnesium chloride. The British Journal of Nutrition, 52(3).
DOI: 10.1079/bjn19840120