Hydroboration-Oxidation Reaction:
Indirect hydration of alkenes can also be done by hydroboration-oxidation which is completed in two steps. In the first step, alkenes react with diborane (B2H6) as boron hydride (BH3) to form an alkyl borane. In fact, the boron atom along with the hydrogen atom gets attached to the double bonded carbon atom with more number of hydrogen atoms. One hydrogen atom is then transferred to the other carbon atom. In this manner, all the three hydrogen atoms of boron are transferred to alkene molecule to form trialkyl borane as the product. In the next step, the alkyl borane is oxidized by alkaline H2O2 to form an alcohol. The indirect hydration process according to Antimarkownikov’s rule.
For example:
