2,4,6-Trichlorobenzoyl chloride or Yamaguchi's reagent is an chlorinated aromatic compound that is commonly used in a variety of organic syntheses.
It is the primary reactant in Yamaguchi esterification. 2,4,6-Trichlorobenzoyl chloride readily reacts with alcohols. This newly formed reagent, when mixed with a stoichiometric amount of 4-dimethylaminopyridine, cyclizes and forms esters. This reaction creates 2,4,6-trichlorobenzoic acid as a byproduct.
2,4,6-Trichlorobenzoyl chloride is prepared by reacting 2,4,6-trichloroaniline with n-butyllithium in a carbon dioxide atmosphere. This produces 2,4,6-trichlorobenzoic acid, which can then be refluxed in thionyl chloride to form 2,4,6-trichlorobenzoyl chloride.
Since 2,4,6-trichlorobenzoic acid is produced as a by product of the Yamaguchi esterification process, it can be refluxed again to recreate 2,4,6-trichlorobenzoyl chloride.