Article / Updated 03-26-2016
Hydration, or adding water across a double bond to make an alcohol, is a reaction that's similar to the addition of a hydrohalic acid across a double bond. Two different reactions accomplish the hydration. The first reaction adds the alcohol (OH group) to the most substituted carbon on the double bond to make the Markovnikov product, and the complementary reaction puts the alcohol on the least substituted carbon in the double bond to make the anti-Markovnikov product.