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

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.

Epoxide Ring-Opening Reaction by HX

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.

Frequently Asked Questions on HBr Reaction

Q1

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.

Q2

Why is sulphuric acid less preferred for manufacturing HBr from sodium bromide or potassium bromide solution?

Sulphuric acid is less preferred for manufacturing HBr from sodium bromide or potassium bromide solution because sulfuric acid oxidises HBr to bromine.

Q3

How can you synthesise HBr?

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

KBr + H2SO4 → KHSO4 + HBr

Q4

What are the applications of HBr?

  • 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.
Q5

What happens when propene reacts with HBr?

Propene reacts with HBr via an addition mechanism to form 2-bromopropane and 1-bromopropane as the product.

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