title: Geminal halide hydrolysis
text: # 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.
  
  