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4: Alkenes and Alkynes

  • Page ID
    337912
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    • 4.1: Introduction to Alkenes
      Alkenes are a class of hydrocarbons (i.e., containing only carbon and hydrogen). They are unsaturated compounds with at least one carbon-to-carbon double bond. The double bond makes Alkenes more reactive than alkanes. Olefin is another term used to describe alkenes.
    • 4.2: Calculating Degree of Unsaturation
      Calculating the degrees of unsaturation is useful information since knowing the degrees of unsaturation make it easier for one to figure out the molecular structure; it helps one double-check the number of π bonds and/or cyclic rings.
    • 4.3: Naming Alkenes
      Alkenes contain carbon-carbon double bonds and are unsaturated hydrocarbons with the molecular formula is CnH2n; this is also the same molecular formula as cycloalkanes. For straight chain alkenes, it is the same basic rules as nomenclature of alkanes except change the suffix to "-ene."
    • 4.4: Cis-Trans Isomerism in Alkenes
      Geometric isomerism (also known as cis-trans isomerism or E-Z isomerism) is a form of stereoisomerism. Isomers are molecules that have the same molecular formula, but have a different arrangement of the atoms in space. That excludes any different arrangements (structural isomerism) which are simply due to the molecule rotating as a whole, or rotating about particular bonds. Structural isomerism is not a form of stereoisomerism, and is dealt with in a separate Module.
    • 4.5: Sequence Rules - The E,Z Designation
      The traditional system for naming the geometric isomers of an alkene, in which the same groups are arranged differently, is to name them as cis or trans. However, it is easy to find examples where the cis-trans system is not easily applied. IUPAC has a more complete system for naming alkene isomers. The R-S system is based on a set of "priority rules", which allow you to rank any groups. The IUPAC system for naming alkene isomers, called the E-Z system, is based on the same priority rules.
    • 4.6: Sequence Rules - The E,Z Designation
      The traditional system for naming the geometric isomers of an alkene, in which the same groups are arranged differently, is to name them as cis or trans. However, it is easy to find examples where the cis-trans system is not easily applied. IUPAC has a more complete system for naming alkene isomers. The R-S system is based on a set of "priority rules", which allow you to rank any groups. The IUPAC system for naming alkene isomers, called the E-Z system, is based on the same priority rules.
    • 4.7: Electrophilic Addition Reactions of Alkenes
      This page looks at the reaction of the carbon-carbon double bond in alkenes such as ethene with hydrogen halides such as hydrogen chloride and hydrogen bromide. Symmetrical alkenes (like ethene or but-2-ene) are dealt with first. These are alkenes where identical groups are attached to each end of the carbon-carbon double bond.
    • 4.8: Naming the Alkynes
    • 4.9: Properties and Bonding in the Alkynes
    • 4.10: Reduction of Alkynes- The Relative Reactivity of the Two \(\pi\) Bonds
    • 4.11: Electrophilic Addition Reactions of Alkynes
    • 4.12: Videos
      The OER Remixer is a self-service tool to rapidly assemble a LibreText from existing sources. This tutorial will include both an explanation of the User Interface as well as a walkthrough of how to do basic tasks.


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