Hydrogen Peroxide and Di(hydroperoxy)propane Adducts of Phosphine Oxides as Stoichiometric and Soluble Oxidizing Agents

Abstract

Aqueous hydrogen peroxide is widely used as an oxidizing agent in industry and academia. Herein, the hydrogen peroxide adducts of phosphine oxides, [tBu3PO⋅H2O2]2 and [Ph3PO⋅H2O2]2⋅H2O2, are described. Additionally, the corresponding di(hydroperoxy)propane adducts R3PO⋅(HOO)2CMe2 (R=Cy, Ph) were synthesized and characterized. All adducts could be obtained as large single crystals suitable for structural characterization by X-ray crystallography and solid-state NMR spectroscopy. The di(hydroperoxy)propane adducts are soluble in organic solvents which enables oxidation reactions in one phase. As the adducts are solid and molecular, they can easily be applied stoichiometrically. No loss of oxidizing power occurs upon long-term storage of the single crystals at room temperature or the powders at -20 °C.

Hydrogen Peroxide and Di(hydroperoxy)propane Adducts of Phosphine Oxides as Stoichiometric and Soluble Oxidizing Agents

“…The chemical shift changes of the two signals with the orientation of the crystal in the magnetic field is different, as described for other cases. TheX -ray structure of (5) [24,28] (Figure S4) matches the structural trend evident in 3 and 4 (Figure 3a nd Figure 4). TheX -ray structure of (5) [24,28] (Figure S4) matches the structural trend evident in 3 and 4 (Figure 3a nd Figure 4).…”

“…[25,29] To increase the number of active oxygen atoms per phosphine oxide mass and to probe the general structure of the di(hydroperoxy)propane adducts,1 ,2-bisdiphenylphosphinoethane (dppe) was treated with acetone and aqueous H 2 O 2 .T he expected di(hydroperoxy)propane adduct [CH 2 Ph 2 PO·(HOO) 2 CMe 2 ] 2 (5)w as obtained. [24] One of the most important advantages of the di(hydroperoxy)propane adducts of phosphine oxides with respect to their application as oxidizing agents is that they are very soluble in organic solvents,r endering biphasic reaction mixtures obsolete.The solubilities of 3 and 4 in representative organic solvents have been quantified ( Figure 6; Table S1). [24] One of the most important advantages of the di(hydroperoxy)propane adducts of phosphine oxides with respect to their application as oxidizing agents is that they are very soluble in organic solvents,r endering biphasic reaction mixtures obsolete.The solubilities of 3 and 4 in representative organic solvents have been quantified ( Figure 6; Table S1).…”

“…Recently,h ydrogen bonding between P=Oa nd phenol OH groups has also been used to create dimeric motifs. [24] Most probably,d ue to the rigid nature and sterics of the phenyl groups,a dditional H 2 O 2 molecules can be accommodated in the space between the dimers. [27] Our attempt to reproduce this result led to the formation of the new adduct [Ph 3 PO·H 2 O 2 ] 2 ·H 2 O 2 (2;F igure 2).…”

“…Figure 5 displays the 31 PCP( cross-polarization) NMR spectra of Figure 1. [24] Thermal ellipsoids are set at 50 %p robability.H ydrogen atoms are omitted for clarity. [24] Thermal ellipsoids are set at 50 %p robability.H ydrogen atoms are omitted for clarity.…”

“…[24] Thermal ellipsoids are set at 50 %p robability.H ydrogen atoms are omitted for clarity. [24] The top H 2 O 2 molecule belongs to the neighboring unit cell. Single-crystalX -ray structure of [Ph 3 PO·H 2 O 2 ] 2 ·H 2 O 2 (2).…”