Solvent-free mechanochemical chlorination of pyrazoles with trichloroisocyanuric acid

A solvent-free, rapid and operationally simple method for the chlorination of pyrazoles with trichloroisocyanuric acid to access 4-chloropyrazole derivatives is described. This high-yielding protocol avoids tedious column chromatography and reduces solvent consumption. Mechanistic studies suggested an electrophilic aromatic substitution mechanism. This system also gives good green chemistry metrics.

Automated summary

A solvent-free, rapid, and operationally simple method for chlorinating pyrazoles with trichloroisocyanuric acid to obtain 4-chloropyrazole derivatives is presented. This high-yielding protocol eliminates the need for tedious column chromatography and reduces solvent consumption. Mechanistic studies suggest an electrophilic aromatic substitution mechanism. The system also demonstrates good green chemistry metrics.