| Most, if not all, of the traditional oxidizing agents covered in an undergraduate lecture course are transition metal based reagents which are toxic and are also potential environmental pollutants. While the ease and efficiency (% yield) of the oxidation reactions using these reagents are highlighted during the lecture class, the deleterious health and environmental aspects of these reagents are often ignored or omitted in classroom discussions. A green oxidation procedure for oxidation of alcohols using catalytic amounts of in-situ generated o-iodoxybenzoic acid (IBX) in presence of Oxone as a stoichiometric oxidant is developed. Catalytic amount of commercially available 2-iodobenzoic acid (2-IBAcid) is used as the organoiodine precursor for IBX in the reaction. Optimization of two oxidation procedures using catalytic amounts of in-situ generated IBX were carried out using 1-octanol and isoborneol as substrates. Experimental parameters including substrate to 2-IBAcid ratio, amount of Oxone the stoichiometric oxidant used, composition of aqueous solvent mixture, nature of extraction solvent and reaction time were optimized. The finalized convenient procedures for the oxidation of alcohols, completed in a 2.5 h laboratory period, is carried out in aqueous acetonitrile using 0.3 equiv. of 2-IBAcid and 2.2 equiv. of Oxone at 65 °C. Students are introduced to several pedagogically relevant green chemistry principles including the use of aqueous reaction medium, non-extractive product isolation procedure, and use of benign and catalytic reagents through this convenient oxidation experiment. Finally, this experiment also allow instructors to discuss the use of IBX and other hypervalent iodine reagents as benign alternatives to commonly used and frequently discussed transition metal based reagents. |
