Geminal halide hydrolysis
# Geminal halide hydrolysis

Geminal halide hydrolysis is an organic reaction. The reactants are geminal dihalides with a water molecule or a hydroxide ion. The reaction yields ketones from secondary halides or aldehydes from primary halides.

## Reaction mechanism

The first part of the reaction mechanism consists of an ordinary nucleophilic aliphatic substitution to produce a gem-halohydrin:

    $RCH(Cl)_2$ + KOH ⟶{\textstyle \longrightarrow } RCH(OH)Cl + KCl

The remaining halide is a good leaving group and this enables the newly created hydroxy group to convert into a carbonyl group by expelling the halide:

    RCH(OH)Cl ⟶{\textstyle \longrightarrow }Rearrangement gives R-CHO + HCl

## Variations

Other functional groups can undergo similar hydrolysis reactions. For instance, geminal trihalides (e.g. benzotrichloride) can be partially hydrolyzed to acyl halides (e.g. benzoyl chloride) in a similar way. Further hydrolysis yields carboxylic acids.

