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    MODULE 4 Alkenes and Alkynes

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    Sittie Fahieda Aloyodan
    This document provides information on the structure, nomenclature, and reactions of alkenes and alkynes. It discusses how alkenes contain carbon-carbon double bonds and alkynes contain carbon-carbon triple bonds. The document outlines IUPAC nomenclature rules for naming alkenes and alkynes, including parent chain identification and numbering of double/triple bonds and substituents. It also summarizes several important reactions of alkenes and alkynes, such as electrophilic addition, reduction, oxidation, and polymerization. Radical addition reactions are discussed for alkene polymer synthesis.

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    MODULE 4 Alkenes and Alkynes

    Uploaded by

    Sittie Fahieda Aloyodan
    144 views19 pages
    This document provides information on the structure, nomenclature, and reactions of alkenes and alkynes. It discusses how alkenes contain carbon-carbon double bonds and alkynes contain carbon-carbon triple bonds. The document outlines IUPAC nomenclature rules for naming alkenes and alkynes, including parent chain identification and numbering of double/triple bonds and substituents. It also summarizes several important reactions of alkenes and alkynes, such as electrophilic addition, reduction, oxidation, and polymerization. Radical addition reactions are discussed for alkene polymer synthesis.

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    MODULE-4-Alkenes-and-Alkynes

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    This document provides information on the structure, nomenclature, and reactions of alkenes and alkynes. It discusses how alkenes contain carbon-carbon double bonds and alkynes contain carbon-carbon triple bonds. The document outlines IUPAC nomenclature rules for naming alkenes and alkynes, including parent chain identification and numbering of double/triple bonds and substituents. It also summarizes several important reactions of alkenes and alkynes, such as electrophilic addition, reduction, oxidation, and polymerization. Radical addition reactions are discussed for alkene polymer synthesis.

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    © All Rights Reserved
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    144 views19 pages

    MODULE 4 Alkenes and Alkynes

    Uploaded by

    Sittie Fahieda Aloyodan
    This document provides information on the structure, nomenclature, and reactions of alkenes and alkynes. It discusses how alkenes contain carbon-carbon double bonds and alkynes contain carbon-carbon triple bonds. The document outlines IUPAC nomenclature rules for naming alkenes and alkynes, including parent chain identification and numbering of double/triple bonds and substituents. It also summarizes several important reactions of alkenes and alkynes, such as electrophilic addition, reduction, oxidation, and polymerization. Radical addition reactions are discussed for alkene polymer synthesis.

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    © All Rights Reserved
    Download as PPT, PDF, TXT or read online from Scribd
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    of 19

    MODULE 4:

    Alkenes & Alkynes:


    Structure and Nomenclature

    Reactions of Alkenes &


    Alkynes
    Alkenes
    • Hydrocarbons containing double bonds, their
    functional group
    • “Olefin” is often used as a synonym.

    • Unsaturated hydrocarbons
    • Each double bond corresponds to a loss of
    2 hydrogen atoms.
    Nomenclature of Alkenes
    1.) Find and name the parent chain, replace the "ane" ending
    of the parent alkane name with "ene.“Number the double
    bond with the lowest possible number.

    2.) Substitiuents get the lowest possible number


    but priority is given to the double bond.
    Nomenclature of Alkenes
    3.) Cite the substituents in alphabetical order. Use prefixes
    for repeating substituents and for multiple double bonds.
    Nomenclature of Cycloalkenes
    No number designation for the double bond is needed in a
    cycloalkene having one double bond and substituents.

    If a substituent is present on one of the double bonded


    carbons, it automatically gets the number 1.

    Number designations are used if there are two or


    more double bonds.
    Special Nomenclatures
    Common names accepted by IUPAC
    Alkenes with Common Names
    E and Z Designation
    Used to determine if the high priority groups are on the same
    side (“Zusammen”: together) or on the opposite sides
    (“Entgegen”: opposite) of the double bond when cis and trans
    designations are not possible.
    Cahn-Ingold-Prelog Rules (also applied to R and S
    designations of enantiomers)
    E and Z Isomers in Medicinal
    Chemistry

    Sample drug marketed as a combination of E


    and Z isomers.
    Electrophilic Addition of Alkenes

    Addition of Hydrogen Halides


    What is the product?
    Markovnikov’s Rule
    The electrophile adds to the sp2-hybridized carbon bonded to
    the greater number of hydrogens or has lesser alkyl
    substituents.
    The nucleophile adds to the sp2-hybridized carbon bonded to
    the greater number of alkyl substituents or has lesser
    hydrogens.

    A regioselective/regiospecific reaction.
    Other Important Reactions of Alkenes
    1. Electrophilic Addition of:
    •Water

    •Halogens

    •Borane (Hydroboration-Oxidation)

    •Carbenes

    2. Reduction

    3. Oxidation
    Radical Addition Reactions of Alkenes:
    Polymerization (Synthesis of Chain-Growth
    Polymers)
    A polymer is a large or very large molecule built up by repetitive
    bonding of smaller molecules called monomers.
    Initiation – generation of radical catalyst which will react with
    the alkene pi bond forming a new radical.

    Propagation – repetition of the step for hundreds


    and thousands of times to build
    the polymer

    Termination - the chain reaction is ended by


    consumption of the radical
    Common Polymers:
    Polystyrene, PVC & Teflon
    Alkynes
    Hydrocarbons that contain triple bonds
    Acetylene is often used as a synonym.

    General formula: CnH2n–2 (acyclic); CnH2n–4 (cyclic)


    Nomenclature of Alkynes
    In common nomenclature, alkynes are named as
    substituted acetylenes.
    In systematic nomenclature, same rules apply as in
    alkenes and cycloalkenes, but the suffix –yne is
    added instead of –ene.

    Special Nomenclature:
    Important Reactions of Alkynes
    1. Electrophilic Addition of:
    •Hydrogen Halides

    •Water

    •Halogens

    •Borane (Hydroboration-Oxidation)

    2. Reduction

    3. Oxidation
    Formation of Acetylide Anions

    Treatment of terminal alkynes with NaNH2,


    produces acetylide anions.
    Synthesis Using Acetylide Anions:
    Formation of New C–C Bonds (Alkylation
    of Alkynes with Alkyl Halides)
    A terminal alkyne can be produced by alkylating
    acetylene.

    An internal alkyne can further be produced from the


    terminal alkyne.

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