Jasminka Pavlinac,^a Marko Zupan^a,b and Stojan Stavber^a,*

^a Department of Physical and Organic Chemistry, “Jožef Stefan” Institute, Jamova 39, 1000 Ljubljana, Slovenia,
^b Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia
* Corresponding author: E-mail: stojan.stavber@ijs.si

Abstract
Lodine was efficiently introduced into the methoxy substituted aromatic compounds, acetophenone, 1-indanone and 1- tetralone using the elemental iodine / 30% aq. H₂O₂ system under organic solvent-free reaction conditions (SFRC) and two types of iodo-functionalisation through an electrophilic process were observed. Iodination of the aromatic ring in the case of dimethoxy- and trimethoxy benzenes took place, while aryl alkyl ketones were regioselectively iodinated at the alkyl position next to a carbonyl group. Based on the ratio of substrate : I₂ : H₂O₂ required for the most efficient iodo- transformation, two different roles of H₂O₂ in the reaction route can be distinguished. Different forms of H₂O₂ as mediators of iodination, namely 30% aq. H₂O₂ and two solid forms urea-H₂O₂ and sodium percarbonate (2Na₂CO₃ · 3H₂O₂), were comparatively evaluated in terms of efficiency under SFRC. Reactions using 30% aq. H₂O₂ as the mediator of iodination under SFRC were compared with those performed in water as reaction medium.

Keywords: Green chemistry, halogenation, iodination, hydrogen peroxide, solvent-free