Iodination

Overview

Iodine and red phosphorus conditions convert alcohols into iodoalkanes.

Transformation

Alcohols → Iodoalkanes

Equation

3R-OH + PI3 -> 3R-I + H3PO3

Reagents

red phosphorus and I2

Environment

room temperature

Reaction class

halogenation

Mechanism

halogenation

Evidence level

textbook core

Scope and limitations

Scope

Alcohols can be converted into iodoalkanes using iodine and red phosphorus, represented through in situ phosphorus triiodide.

Limitations

This route records the iodoalkane preparation branch; phosphorus triiodide is represented as the effective halogenating species.

Related reactions

• Chlorination: Alcohols → Chloroalkanes

  Alcohols can be converted into chloroalkanes to create a better leaving group for downstream substitution.

• Chlorination with thionyl chloride: Alcohols → Chloroalkanes

  Thionyl chloride converts alcohols into chloroalkanes with sulfur dioxide and hydrogen chloride as by-products.

• Bromination: Alcohols → Bromoalkanes

  Bromide and acid conditions convert alcohols into bromoalkanes.

• Hydroiodination: Alkenes → Iodoalkanes

  Addition of hydrogen iodide across an alkene can form an iodoalkane.

• Hydrolysis: Chloroalkanes → Alcohols

  The C-Cl bond can be displaced by hydroxide to form an alcohol.

• Cyanation: Iodoalkanes → Nitriles

  Cyanide substitution forms a nitrile and extends the carbon chain by one carbon.

• Amination: Iodoalkanes → Amines

  Ammonia substitutes iodide to form a primary amine; excess ammonia limits further alkylation.

• Hydrolysis: Bromoalkanes → Alcohols

  The C-Br bond can be displaced by hydroxide to form an alcohol.

• Hydrolysis: Iodoalkanes → Alcohols

  The C-I bond can be displaced by hydroxide to form an alcohol.

• Elimination: Iodoalkanes → Alkenes

  Base-promoted elimination removes HI to form an alkene.

• Oxidation: Alcohols → Aldehydes

  Controlled oxidation of a primary alcohol gives an aldehyde.

• Oxidation: Alcohols → Ketones

  Oxidation of a secondary alcohol gives a ketone.

• Oxidation: Alcohols → Carboxylic acids

  Full oxidation of a primary alcohol gives a carboxylic acid.

• Hydration: Alkenes → Alcohols

  Catalytic hydration converts alkenes into alcohols.

• Dehydration: Alcohols → Alkenes

  Dehydration converts alcohols into alkenes.

• Esterification co reactant: Alcohols → Esters

  Alcohols combine with carboxylic acids to form esters.

References

1. Pearson Edexcel Level 3 Advanced GCE in Chemistry specificationPearson Education Limited · Pearson qualifications · 2024

   Supports the textbook-core organic reaction routes used for displayed route and mechanism content.