Ortho-phosphite anion synthesized through ball milling offers a safer alternative to white phosphorus
Scientists have developed a novel method to create salts containing ortho-phosphite anions through mechanochemical reduction of phosphate compounds. This breakthrough presents a safer and more versatile option compared to the toxic and flammable white phosphorus, which is commonly used as the starting material for various phosphorus compounds.
Ortho-phosphite, with its unique structure where a central phosphorus atom is bonded to three singly charged oxygen atoms (PO33-), has been a challenging anion to synthesize. Despite its importance in explaining Lewis structures to students, it has remained elusive in practical applications.
Researchers from the US have successfully synthesized various group 1 ortho-phosphite salts, expanding the range of known heavier group 15 trioxyanions. By ball milling phosphate sources with sodium, potassium, or cesium salts for up to 36 hours, they achieved a mixture of reduced phosphorus species.
Advanced spectroscopic techniques, such as solid-state NMR and Raman spectroscopy, identified key peaks corresponding to the ortho-phosphite anion, aligning closely with theoretical predictions. This confirmation allowed the researchers to isolate ortho-phosphite salts as a significant component of the mixture, alongside phosphate, hypophosphate (P2O64-), and phosphide (P3-) compounds.
The versatility of ortho-phosphite as a reagent is a game-changer. It can be easily hydrolyzed to produce phosphite, a valuable phosphorylating agent. Furthermore, reacting the crude mixture with trimethylsilyl chloride results in the synthesis of tris(trimethylsilyl)phosphite, a precursor to a wide array of organophosphorus compounds. While alkylation of ortho-phosphite was successful, purifying the products proved challenging, leading to lower yields.
The researchers believe that this new synthesis method could revolutionize the production of organophosphorus compounds, eliminating the need for white phosphorus. They are now focused on further refining the ortho-phosphite synthesis process and exploring its full potential in various chemical reactions.
