ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Effects of acyl donor type, catalyst type, and reaction conditions on the activity and selectivity of Friedel-Crafts acylation

Adi Wolfson, Rao P. Madhusudhan, Ayelet Shapira-Tchelet, and Miron V. Landau

Green Processes Center, Chemical Engineering Department, Sami Shamoon College of Engineering, P.O. Box 900, Beer-Sheva, 84100, Israel

E-mail: adiw@sce.ac.il

Received: 21 June 2008  Revised: 3 September 2008  Accepted: 29 September 2008

Abstract: Acylation of anisole and 3-methylanisole was performed with several acylating reagents (acetylation by AcCl and Ac₂O and bromoacetylation by BrAcCl and (BrAc)₂O) over different solid acid catalysts. The reaction conditions were optimized with respect to the acylation reagent, overall yield, solid acid catalyst, and the products selectivities. While acylation of anisole with acetyl chloride or acetic anhydride resulted in its full conversion to para-substituted acetophenone, the use of bromoacetyl bromide or bromoacetic anhydride yielded also the ortho-substituted product. Acylation of 3-methylanisole also yielded both para- and ortho-substitutions, and the products distribution was affected by the reaction conditions and catalyst type. It was found that while more acidic catalysts (caesium salt of heteropolyacid and zeolites) were the most active towards anisole acylation, the most active catalysts for the acylation of 3-methylanisole were ion-exchange catalysts. Employing HY-740 zeolite resulted in the highest ortho-selectivity in the acylation of anisole with bromoacetyl bromide and bromoacetic anhydride and in the acylation of 3-methylanisole with acetic anhydride.

Keywords: Friedel-Crafts acylation - solid acids - catalysis - selectivity

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-009-0018-6

Chemical Papers 63 (3) 291–297 (2009)