Traditionally, organic synthesis requires the use of a solution as the reaction medium. Unfortunately, many of the solvents necessary for these reactions are carcinogenic, teratogenic, or toxic. Discarding these solvents poses a major concern to the environment and global health. High-speed ball milling provides an answer to this problem, as these conditions allow reactions to occur with no solvent. Particles are broken down into smaller and smaller pieces by physical impacts. In this way, the reagents can interact on the molecular level and react. One major obstacle for the ball milling community is in the purification process, which currently is chromatography. Chromatography is dictated by polarity, and most of the time a nonpolar, organic solvent is required. Perhaps polymer-supported reagents can provide a better way. Because they are insoluble in both polar and nonpolar solvents, these polymer-supported reagents can be separated from the reaction mixture by simple filtration, which can be accomplished with a �green� solvent. Furthermore, if the polymer-supported reagent is a catalyst, the same polymer sample could be recovered and reused multiple times. With this in mind, we studied a polymer-bound version of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), a radical catalyst used for the oxidation of primary alcohols. Our results have shown that the best oxidant for our system is potassium peroxymonosulfate (OXONE�), giving our reaction a solely aqueous waste stream. Our system has been successful in oxidizing various alcohols, and the TEMPO catalyst can be reused at least three times with no change in catalytic activity.

Recover and reuse: Polymer-supported reagents under ball milling conditions

248th National Meeting (2014)

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