Adsorption of solid phosphines on silica and implications for catalysts on oxide surfaces

Hoefler, John C.; Yang, Yuan; Blümel, Janet

doi:10.1039/d3nj03016d

Cited by 1 publication

(26 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The adsorption takes place within minutes even when no solvent is involved, and the dry components are mixed manually. The dynamics of the phosphine molecules on the silica surface was studied in detail . To test the general nature of the dynamic phenomena and probe the interactions with a surface different from the silica used previously, we applied activated carbon (AC) as the adsorbent.…”

Section: Resultsmentioning

confidence: 99%

“…This is the case when polycrystalline 6 is measured using 31 P MAS NMR at a slow rotational speed of 2 kHz (Figure 3). 10 Phosphine 6 can be adsorbed on AC under an inert atmosphere by manually grinding the solid components in the absence of a solvent. Alternatively, a solution of 6 can be applied to AC, and 6 remains adsorbed when the solvent is removed in vacuo.…”

Section: Adsorption and Oxidation Of Pph 3 (6) On Acmentioning

confidence: 99%

“…55 Searching for an efficient air oxygen-based method for phosphine oxide synthesis remains an attractive goal, and fortunately, we found a new convenient route to selectively oxidize phosphines to the corresponding phosphine oxides. Given the known affinity of phosphines to adsorb on silica, 10 and our previous experience with metallocenes adsorbed on activated carbon (AC), 56,57 we sought to study trialkyl-and triarylphosphines adsorbed on AC. However, we soon discovered that PPh 3 , which is not air sensitive in neat form or dissolved, is readily and selectively oxidized to O�PR 3 when adsorbed on AC and exposed to the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

“…One class of molecules whose adsorption has been studied by our group and others is phosphines. − Owing to the lone electron pair of the P atom, phosphines adsorb, for example, onto porous metal oxide surfaces such as silica via van der Waals interactions . The adsorbed phosphines are highly mobile on the surface, and the adsorption is reversible.…”

Section: Introductionmentioning

confidence: 99%

“…The adsorbed phosphines are highly mobile on the surface, and the adsorption is reversible. This phenomenon has been studied using multinuclear solid-state NMR spectroscopy, which is a powerful technique for surface species and materials characterization. − …”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Surface-Assisted Selective Air Oxidation of Phosphines Adsorbed on Activated Carbon

Hoefler,

Jackson,

Blümel

2024

Inorg. Chem.

Self Cite

View full text Add to dashboard Cite

Trialkyl- and triarylphosphines readily adsorb onto the surface of porous activated carbon (AC) even in the absence of solvents through van der Waals interactions between the lone electron pair and the AC surface. This process has been proven by solid-state NMR techniques. Subsequently, it is demonstrated that the AC enables the fast and selective oxidation of adsorbed phosphines to phosphine oxides at ambient temperature in air. In solution, trialkylphosphines are oxidized to a variety of P(V) species when exposed to the atmosphere, while neat or dissolved triarylphosphines cannot be oxidized with air. When the trialkyl- and triarylphosphines P n Bu3 (1), PEt3, (2), P n Oct3 (3), PMe t Bu2 (4), PCy3 (5), and PPh3 (6) are adsorbed in a mono- or submonolayer on the surface of AC, in the absence of a solvent and at ambient temperature, they are quantitatively oxidized to the adsorbed phosphine oxides, 1 ox –6 ox , once air is admitted. No formation of any unwanted P(V) side products or water adducts is observed. The phosphine oxides can then be recovered in good yields by washing them off of the AC. The oxidation is likely facilitated by a radical activation of molecular oxygen due to delocalized electrons on the aromatic surface coating of AC, as proven by ESR. This easy and inexpensive oxidation method renders hydrogen peroxide or other oxidizers unnecessary and is broadly applicable to sterically hindered and even to air-stable triarylphosphines. Phosphines adsorbed at lower surface coverages on AC oxidize at a faster rate. All oxidation reactions were monitored by solution- and solid-state NMR spectroscopy.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Adsorption and Oxidation Of Pph 3 (6) On Acmentioning

confidence: 99%