Synthesis of 2-Acetylthiophene by the Acylation of Thiophene Using Acetic Anhydride and Iodine (A Revisiting after Almost Sixty Years)

Herein is described an experimental procedure for an electrophilic aromatic substitution utilizing a heterocyclic substrate instead of the more commonly used benzenoid substrates. Thiophene is acetylated under mild conditions using acetic anhydride and iodine. This method was reported almost sixty years ago as part of a series of thiophene acetylation experiments involving various acetylating agents and various Lewis acid catalysts. A report on the spectra of the product (not given in the original work) is now included, as well as an alternative final distillation and purification procedure. While not originally conceived as a college laboratory exercise, this experiment is excellent for those wanting to include heterocyclic chemistry in their laboratory course.