Skip to main content
Chemistry LibreTexts

8.8: Stereochemistry of Reactions - Hydration of Chiral Alkenes

  • Page ID
    182947
  • Learning Objective

    • discern the stereochemical differences between the EAR of chiral and achiral alkenes

    Stereochemistry - the Subtle Details

    In the previous section, the addition of water to the achiral alkene produced a racemic mixture of two enantiomeric alcohols. They are produced in equal amounts so the mixture is optically inactive. What would occur if we carried out a similar reaction on a chiral alkene? Consider (S)-3-methyl-1-pentene reacting with water (acid catalyzed). Proton addition produces a carbocation intermediate that is chiral (* denotes stereogenic centre). That intermediate does not have a plane of symmetry and therefore attack by water is not equal from the top and bottom. This ultimately produces R and S products in a non 50:50 ratio as shown in the mechanism below.

    alkene chiral hydration.png

    Exercise

    1. Predict the products of the following reaction showing stereochemistry.

    Answer

    1. The products are diastereomers of one another.

    Contributors