Zinc bromide
[CAS# 7699-45-8]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal halides and halides >> Metal bromide and salt
• Name: Zinc bromide
• Molecular Formula: ZnBr₂
• Molecular Weight: 225.19
• CAS Registry Number: 7699-45-8
• EC Number: 231-718-4
• SMILES: [Zn+2].[Br-].[Br-]

Properties

• Density: 4.201 g/mL
• Melting point: 394 °C
• Index of Refraction: 1.5452
• Boiling point: 650 °C
• Water solubility: soluble, 447 g/100 mL (20 °C)

Safety Data

• Hazard Symbols: GHS05;GHS07;GHS09 Danger
• Risk Statements: H302-H314-H317-H318-H400-H410-H411
• Safety Statements: P260-P261-P264-P264+P265-P270-P272-P273-P280-P301+P317-P301+P330+P331-P302+P352-P302+P361+P354-P304+P340-P305+P354+P338-P316-P317-P321-P330-P333+P317-P362+P364-P363-P391-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Acute toxicity	Acute Tox.	4	H302
Skin sensitization	Skin Sens.	1	H317
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Serious eye damage	Eye Dam.	1	H318
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin corrosion	Skin Corr.	1C	H314
Skin corrosion	Skin Corr.	1A	H314

• Transport Information: UN 3260

Discovery and Applications

Zinc bromide (ZnBr₂) is an inorganic compound formed by the reaction of zinc with bromine. It was first synthesized in the early 19th century as chemists began to explore the properties of halides and their potential applications. Zinc bromide appears as a white crystalline solid, readily soluble in water and alcohol, and is hygroscopic, meaning it can absorb moisture from the environment.

The synthesis of zinc bromide can be achieved through several methods, including the direct combination of elemental zinc and bromine, or by neutralizing zinc oxide with hydrobromic acid. The compound’s ability to form hydrates, such as the dihydrate form (ZnBr₂·2H₂O), adds to its versatility in various applications.

Zinc bromide is widely utilized in a variety of industrial and commercial applications. One of its primary uses is in the oil and gas industry, where it serves as a high-density drilling fluid. The high density of zinc bromide solutions allows for better control of wellbore pressures during drilling operations. This is particularly important in preventing blowouts and ensuring the safety of drilling activities in high-pressure environments. The use of zinc bromide-based fluids has become increasingly popular due to their effectiveness and lower environmental impact compared to other drilling fluids.

In addition to its application in drilling fluids, zinc bromide is also employed in the preparation of various chemical compounds. It serves as a reagent in organic synthesis, particularly in reactions involving the formation of organozinc compounds. These organozinc intermediates are valuable in the production of pharmaceuticals, agrochemicals, and fine chemicals. The versatility of zinc bromide as a reagent makes it an important tool in synthetic organic chemistry.

Moreover, zinc bromide is utilized in the manufacture of optical glass and as a component in the formulation of certain types of batteries. Its high refractive index and transparency in the visible spectrum make it suitable for use in specialized optical applications, including infrared optical components. In batteries, zinc bromide serves as a component in certain rechargeable battery systems, contributing to improved energy storage capabilities.

The compound is also known for its use in photographic processes, particularly in the preparation of certain types of photographic emulsions. Its ability to enhance the sensitivity of light-sensitive materials has made it valuable in the field of photography, although this application has diminished with the rise of digital photography.

Despite its useful applications, zinc bromide must be handled with care due to its potential health hazards. It is classified as harmful if ingested or inhaled, and precautions should be taken to avoid skin and eye contact. Proper safety measures, including the use of personal protective equipment, are essential when working with this compound in laboratory or industrial settings.

In summary, zinc bromide is a significant inorganic compound with a range of applications in the oil and gas industry, organic synthesis, optical materials, and photography. Its discovery and subsequent use have greatly contributed to advancements in various fields, highlighting its role as a valuable chemical in modern industrial practices.

References

2007. Nickel-catalyzed Carboannulation Reaction of o-Bromobenzyl Zinc Bromide with Unsaturated Compounds. Organic Letters, 9(23).
DOI: 10.1021/ol702167t

2010. Palladium-Catalyzed Cross-Coupling of Cyclopropylmagnesium Bromide with Aryl Bromides Mediated by Zinc Halide Additives. The Journal of Organic Chemistry, 75(17).
DOI: 10.1021/jo100983c

2015. Diastereoselective, Zinc-Catalyzed Alkynylation of α-Bromo Oxocarbenium Ions. Organic Letters, 17(15).
DOI: 10.1021/acs.orglett.5b01838