After completing this section, you should be able to account for the stereochemistry of the product of the addition of water to an alkene in terms of the formation of a planar carbocation.
Organic reactions in the laboratory or in living systems can produce chiral centres. Consider reaction of 1-butene with water (acid catalyzed). Markovnikov regiochemistry occurs and the OH adds to the second carbon. However, both R and S products occur giving a racemic (50/50) mixture of 2‑butanol. How does this occur? The proton addition to 1‑butene results in a planar carbocation intermediate. A molecule of water is then equally likely to attack from the top or the bottom of this cation to produce either (S)‑2‑butanol or (R)‑2‑butanol, respectively.