HBr Reaction

What is HBr?

Hydrogen Bromide, abbreviated as HBr, is an inorganic compound. When added to water, it forms hydrobromic acid. HBr and its aqueous solution are generally used as a reagent in synthesising bromide compounds.

Table of Content

• HBr Reaction
• HBr Synthesis
• HBr Applications
• Frequently Asked Questions – FAQs

HBr Reaction

Hydrogen Bromide, abbreviated as HBr, is an inorganic compound. HBr and its aqueous solution are generally used as a reagent in synthesising bromide compounds.

• HBr reacts with an alkene to form an alkyl bromides complex.
• It reacts with alcohol to form an alkyl bromide.
• It reacts with an alkyne to form a bromoalkene.
• It reacts with epoxide to form bromohydrin.
• It reacts with an alkyl halide to yield corresponding substitution production.
• It reacts with VCl₄ via a redox reaction to form the VBr₃ complex.

Reaction with Alkene

HBr reacts with an alkene via an addition mechanism to form an alkyl bromides complex.

RCH=CH₂ + HBr → R−CHBr−CH₃

Reaction with Alcohol

HBr reacts with alcohol via a substitution mechanism to form an alkyl bromides complex.

CH₃CH₂CH₂OH + HBr → CH₃CH₂CH₂Br + H₂O

Reaction with Alkyne

HBr reacts with an alkyne via an addition mechanism to form a bromoalkene complex.

RC≡CH + HBr → RC(Br)=CH₂

Reaction with Epoxide

HBr reacts with epoxide. It opens its ring structure to generate a trans bromohydrin.

Reaction with Alkyl Halide

HBr reacts with an alkyl halide via a substitution mechanism to form an alkyl bromide complex.

HBr + CH₂BrCl → HCl + CH₂Br₂

Reaction with Inorganic Compound

HBr reacts with VCl₄ via a redox reaction to form the VBr₃ complex.

2 VCl₄ + 8 HBr → 2 VBr₃ + 8 HCl + Br₂

HBr Synthesis

• We can synthesise HBr by the distillation of sodium bromide or potassium bromide solution with phosphoric acid.

KBr + H₂SO₄ → KHSO₄ + HBr

The above reaction can also proceed in sulphuric acid solution, but it is less preferred because sulfuric acid oxidises HBr to bromine.

2 HBr + H₂SO₄ → Br₂+ SO₂ + 2 H₂O

• We can synthesise HBr by reacting sulphur water and bromine.

2 Br₂+ S + 2 H₂O→ 4 HBr + SO₂

• We can synthesise HBr by bromination of tetralin.

C₁₀H₁₂ + 4 Br₂ → C₁₀H₈Br₄ + 4 HBr

• We can synthesise HBr by reduction of bromine with phosphorous acid.

Br₂ + H₃PO₃ + H₂O → H₃PO₄ + 2 HBr

• Industrially, we synthesise HBr by combining hydrogen and bromine at 200° C and 400 ° C. It is catalysed by asbestos or platinum.

HBr Applications

• HBr and its aqueous solution are generally used as a reagent in synthesising bromide compounds.
• It is used as a source of bromine in industrial syntheses.
• HBr is a strong acid. Thus, it is used to prepare catalysts in PTA/PET production.
• Anhydrous HBr is dangerous and is shipped in high-pressure cylinders.
• It is used as a sanitising or disinfecting agent.