Ferric chloride hexahydrate
[CAS# 10025-77-1]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal halides and halides >> Metal chlorides and salts
• Name: Ferric chloride hexahydrate
• Synonyms: Iron(III) chloride hexahydrate
• Molecular Formula: FeCl₃.6(H₂O)
• Molecular Weight: 270.29
• CAS Registry Number: 10025-77-1
• EC Number: 600-047-2
• SMILES: O.O.O.O.O.O.[Cl-].[Cl-].[Cl-].[Fe+3]

Properties

• Density: 1.82 g/mL
• Melting point: 37 °C
• Boiling point: 280-285 °C
• Water solubility: 920 g/L (20 °C)

Safety Data

• Hazard Symbols: GHS05;GHS07 Danger
• Risk Statements: H302-H315-H318
• Safety Statements: P264-P280-P301+P312-P302+P352-P305+P351+P338-P332+P313

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Serious eye damage	Eye Dam.	1	H318
Skin irritation	Skin Irrit.	2	H315
Skin corrosion	Skin Corr.	1B	H314
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Skin corrosion	Skin Corr.	1C	H314
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin corrosion	Skin Corr.	1A	H314
Specific target organ toxicity - repeated exposure	STOT RE	2	H373

• Transport Information: UN 1773

Discovery and Applications

Ferric chloride hexahydrate, known as iron(III) chloride hexahydrate (FeCl₃·6H₂O), is an important chemical compound with diverse applications. This substance, appearing as yellow-orange crystals, has a history rooted in early alchemical explorations of metal salts. The discovery of its hexahydrate form likely occurred when iron was dissolved in hydrochloric acid, resulting in a hydrated crystalline structure that is more stable and easier to handle than the anhydrous form.

One of the primary uses of ferric chloride hexahydrate is in water treatment. It acts as a coagulant, aiding in the removal of impurities from drinking water and wastewater. When added to water, it hydrolyzes to form ferric hydroxide, which aggregates suspended particles, facilitating their removal through filtration or sedimentation. This makes the compound vital in ensuring clean water supplies.

Another significant application is in the etching of metals, particularly in the production of printed circuit boards (PCBs). Ferric chloride hexahydrate etches copper, creating the necessary patterns for electronic circuits by oxidizing and dissolving the copper layer. This process highlights the compound’s effectiveness as an oxidizing agent, essential in precision manufacturing.

In organic chemistry, ferric chloride hexahydrate serves as a catalyst in various reactions, including the Friedel-Crafts acylation and alkylation. Its strong Lewis acid properties allow it to activate electrophiles, facilitating the formation of carbon-carbon bonds in aromatic compounds. Additionally, it is used as a reagent in analytical chemistry, particularly in the qualitative detection of phenols, which form colored complexes upon reaction with ferric ions.

Ferric chloride hexahydrate has also found uses in medical applications, such as the treatment of hyperhidrosis (excessive sweating) and in hemostatic agents to control bleeding. Its ability to coagulate proteins and form insoluble complexes makes it effective in these therapeutic contexts.

Despite its utility, ferric chloride hexahydrate must be handled with caution due to its corrosive nature and potential environmental impact. It can cause skin and eye irritation, and its fumes can be harmful if inhaled. Proper safety measures and environmental precautions are essential when working with this compound, particularly in industrial settings where large quantities are used.

The study and application of ferric chloride hexahydrate continue to expand, with ongoing research into its role in environmental remediation and advanced material synthesis. As a versatile compound with a wide range of applications, it remains a staple in both industrial and scientific fields, demonstrating the enduring relevance of basic chemical research.

References

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