Cyanation

Overview

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

Transformation

Chloroalkanes → Nitriles

Equation

R-Cl + CN- -> R-CN + Cl-

Reagents

KCN or NaCN

Environment

ethanol, reflux

Reaction class

nucleophilic substitution

Mechanism

nucleophilic substitution

Evidence level

textbook core

Scope and limitations

Scope

Cyanide substitution of chloroalkanes; the carbon chain increases by one carbon.

Limitations

Cyanide reagents are hazardous; the mechanism diagram uses a primary chloroalkane exemplar in which CN- attacks through carbon to give a nitrile. Other cyanide sources or conditions, such as silver cyanide, can favour isocyanide products and belong to a separate route.

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.

• Hydrochlorination: Alkenes → Chloroalkanes

  Addition of hydrogen chloride across an alkene can form a chloroalkane.

• Hydrolysis: Chloroalkanes → Alcohols

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

• Cyanation: Bromoalkanes → Nitriles

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

• Cyanation: Iodoalkanes → Nitriles

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

• Amination: Chloroalkanes → Amines

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

• Elimination: Chloroalkanes → Alkenes

  Base-promoted elimination removes HCl to form an alkene.

• Hydrolysis: Nitriles → Carboxylic acids

  Nitriles can be hydrolysed to carboxylic acids, splitting the old aggregate nitrile-to-amide route into a single functional-group conversion.

• Reduction: Nitriles → Amines

  Nitriles can be reduced to primary amines, separating the amine feedstock route from later amide or materials chemistry.

• Free radical chlorination: Alkanes → Chloroalkanes

  Photochemical chlorination can convert alkanes into chloroalkanes.

• Grignard formation: Chloroalkanes → Grignard reagents

  Chloroalkanes can react with magnesium in dry ether to form Grignard reagents.

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.