Nencki reaction

What is Nencki reaction?

Nencki et al. first described this reaction in 1881, which involves the activation of acylation by zinc chloride ZnCl2 between a phenol and an acyl chloride, anhydride, or carboxylic acid. Hence, it is widely referred to as the Nencki reaction.

Nencki reaction - general reaction scheme
Nencki reaction
  • R = alkyl, aryl
  • X = halo, OC(O)R

The reaction usually requires at least one equivalent of zinc chloride, but it does not involve complex formation between zinc chloride ZnCland acyl chloride or anhydride, unlike aluminum chloride AlCl3. Additionally, it has been discovered that larger acylating agents lead to reduced para-acylation regioselectivity.


  • Nencki, M. and Sieber, N., J. Prakt. Chem., 1881, 23, 147
  • Nencki, M. and Sieber, N., J. Prakt. Chem., 1881, 23, 150