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Chemistry LibreTexts

22.17 Nitriles

  • Page ID
    28428
  • Synthesis of Nitriles

    Nitriles are formed by an SN2 reaction between a bromide and sodium cyanide

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    Reactivity of Nitriles

    The carbon in a nitrile is electrophilic because a resonance structure can be drawn which places a positive charge on it. Because of this the triple bond of a nitrile accepts a nucleophile in a manner similar to a carbonyl.

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    Hydrolysis of Nitriles

    Nitriles can be converted to carboxylic acid with heating in sulfuric acid. During the reaction an amide intermediate is formed.

    General Reaction

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    Example

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    Reduction of Nitriles

    Nitriles can be converted to 1° amines by reaction with LiAlH4. During this reaction the hydride nucleophile attacks the electrophilic carbon in the nitrile to form an imine anion. Once stabilized by a Lewis acid-base complexation the imine salt can accept a second hydride to form a dianion. The dianion can then be converted to an amine by addition of water.

    General Reaction

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    Going from reactants to products simplified

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    Example

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    Mechanism

    1) Nucleophilic Attack by the Hydride

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    2) Second nucleophilic attack by the hydride.

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    3) Protonation by addition of water to give an amine

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    Addition of Grignard Reagents

    Grignard reagents can attack the electophillic carbon in a nitrile to form an imine salt. This salt can then be hydrolyzed to become a ketone.

    General Reaction

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    Example

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    Mechanism

    1) Nucleophilic Attack by the Grignard Reagent

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    2) Protonation

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    3) Protonation

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    4) Nucleophilic attack by water

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    5) Proton Transfer

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    6) Leaving group removal

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    7) Deprotonation

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    Contributors

    Prof. Steven Farmer (Sonoma State University)

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