Session: Undergraduate Research Posters: Green Chemistry & Sustainability:

Recent studies of the Beckmann Rearrangement have shown success in mechanochemical solvent-free methods and the use of Lewis Acid catalysts. The Beckmann Rearrangement, used in the production of lactams that are polymerized into Nylon plastics, is the acid-induced rearrangement of oximes (N=OH) to amides. Efficient transformations producing high yields both from the initial ketone and intermediate oxime product are known, but most industrial methods utilize corrosive sulfuric acid which produces large amounts of ammonium sulfate waste, increasing the negative impact on the environment. One-pot transformations of ketones to amides have shown success in reducing waste and preserving atom economy while producing high yields using alternative acid systems. Mechanochemistry promises to achieve even more environmentally friendly syntheses by reducing solvent use and removing most, if not all, liquid waste. Here, transformations are promoted by the mechanical activation of bonds in absence of a solvent, often by grinding. In this work, the mechanochemical, solvent-free transformation of ketones to oximes and resulting amides through the Beckmann rearrangement was examined as a greener method of synthesis. Mixtures of ketone, hydroxylamine hydrochloride, sodium acetate trihydrate, and solid Lewis Acid catalyst were mechanically ground through automated ball milling with heat. Catalysts investigated include readily obtained I₂, anhydrous AlCl₃, and anhydrous FeCl₃. Transformations to the oxime were successful, but attempts to create the amide via the oxime in one-pot transformations with solid catalysts resulted in no reaction with aromatic compounds, while aliphatic compounds were transformed to oximes. Beckmann products seem to have been obtained from aromatic ketoximes with both AlCl₃ and FeCl₃ suggested from changes in spectral, TLC, and melting point data. The scope of this method and optimization of conditions will be discussed.

Brandy Fox

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