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Hydrobromic Acid

General Information:


CAS Number: 10035-10-6

Molecular Weight: 80.91 g/mol

Appearance: Colorless to light yellow liquid (48% w/w aq.)

Density: 1.49 g/mL (48% w/w aq.)

Hydrobromic acid (HBr) is commonly sold as a 48% (by weight) solution in water. HBr works well as a Lewis acid catalyst but the increased nucleophilicity of bromide relative to chloride generally makes hydrochloric acid the preferable choice. However, in certain reactions such as in the deprotection of methyl ethers, the increased nucleophilicity of bromide is advantageous. HBr is also a reasonable choice in reactions where the presence of bromide already exists, such as Sandmeyer reactions and brominations.

Common Uses:

Reagent/solvent for the deprotection of methyl ethers

Reagent/solvent in bromine-based Sandmeyer reactions

Reagent/solvent in bromination reactions


Hydrobromic acid is very acidic. Contact with skin or eyes can cause severe burns.


1) Patent Reference: WO2007084786, page 115, (9.4 MB)

2) Patent Reference: WO2015051043, page 107, (9.7 MB)

3) Patent Reference: WO2014149164, page 339, (23.7 MB)

4) Wikipedia: Hydrobromic acid (link)

5) Hydrobromic acid (link)

6) Reich, H. J.; Rigby, J. H.; Handbook of Reagents for Organic Synthesis, Acidic and Basic Reagents