Two new classes of superior solid, stable, and stoichiometric oxidizing agents will be described.1,2 Representative hydrogen peroxide and di(hydroperoxy)alkane adducts of phosphine oxides, [R3PO●H2O2]2 and R3PO●(HOO)2CR'R'' (R,R',R'' = alkyl, aryl) will be presented. It will be demonstrated that they are easy to synthesize reproducibly and in high yields. Both types of oxidizing agents crystallize readily in the form of large specimens in cm dimensions. Therefore, they are obtained in high purity and can be fully characterized including with single-crystal X-ray structures. The structural motif is of a general nature for both adduct classes. The reproducible and exact stoichiometric compositions are independent of the substituents R, R', and R''. The oxidative strengths of the adducts have been quantified by an in situ NMR method and their shelf lives, as well as their mechanical and thermal robustness have been explored. Their solubilities in organic solvents are superb, which distinguishes them from aqueous hydrogen peroxide and renders them superior oxidizing agents for applications in one anhydrous organic phase. The mechanism of the formation of the di(hydroperoxy)alkane adducts has been established. All adducts have been tested for the selective oxidation of phosphines to phosphine oxides and sulfides to sulfoxides without overoxidation to phosphinic and phosphonic acids or sulfones, respectively. First exciting results of anhydrous olefin epoxidation reactions will be presented. A protocol has been developed for the straightforward recovery and recycling of the phosphine oxide carriers by immobilizing the phosphine oxides on solid supports. Multinuclear solid-state NMR served to investigate both, large single crystals of the pure adducts and surface-bound species. All results obtained in this project are of basic interest since new substance classes have been investigated. It will be demonstrated that the new adducts increased the general knowledge about oxidative processes and opened up novel synthetic pathways.

Solid, stable, soluble, and stoichiometric oxidizing agents: Hydrogen peroxide and di(hydroperoxy)alkane adducts of phosphine oxides

253rd National Meeting (2017)

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