Sustainable Production of Reduced Phosphorus Compounds: Mechanochemical Hydride Phosphorylation Using Condensed Phosphates as a Route to Phosphite

Abstract

In pursuit of a more sustainable production of phosphorous acid (H 3 PO 3 ), a versatile chemical with phosphorus in the +3 oxidation state, we herein report that condensed phosphates can be employed to phosphorylate hydride reagents under solvent-free mechanochemical conditions to furnish phosphite (HPO 3 2– ). Using potassium hydride as the hydride source, sodium trimetaphosphate (Na 3 P 3 O 9 ), triphosphate (Na 5 P 3 O 10 ), pyrophosphate (Na 4 P 2 O 7 ), fluorophosphate (Na 2 PO 3 F), and polyphosphate (“(NaPO 3 ) n ”) engendered phosphite in optimized yields of 44, 58, 44, 84, and 55% based on total P content, respectively. Formation of overreduced products including hypophosphite (H 2 PO 2 – ) was identified as a competing process, and mechanistic investigations revealed that hydride attack on in-situ-generated phosphorylated phosphite species is a potent pathway for overreduction. The phosphite generated from our method was easily isolated in the form of barium phosphite, a useful intermediate for production of phosphorous acid. This method circumvents the need to pass through white phosphorus (P 4 ) as a high-energy intermediate and mitigates involvement of environmentally hazardous chemicals. A bioproduced polyphosphate was found to be a viable starting material for the production of phosphite. These results demonstrate the possibility of accessing reduced phosphorus compounds in a more sustainable manner and, more importantly, a means to close the modern phosphorus cycle.

Silicon and Carbon nanocages as catalysts of CO 2 reduction reaction

“…In recent years, the chemical researchers demonstrated that he important organic chemical structures such as CO [8], CH 4 [9], HCOOH [10], HCHO [11] and CH 3 OH [12] are possible products of processes of CO 2 reduction reaction [13].…”

Catalytic potential of silicon nanocages for CO2 reduction reaction to CO, CH4, HCOOH, HCHO and CH3OH production

“…In recent years, the chemical researchers demonstrated that he important organic chemical structures such as CO [8], CH 4 [9], HCOOH [10], HCHO [11] and CH 3 OH [12] are possible products of processes of CO 2 reduction reaction [13].…”

Reducing the P-Cycle by Grinding

“…In this issue of ACS Central Science , Cummins and co-workers report a facile and selective reduction of polyphosphates to phosphite with potassium hydride via mechanosynthesis, a potential solution toward a “greener” phosphorus industry. 1 Phosphorus generally exists in its highest oxidation state in nature and is a vital element for living organisms. It constitutes approximately 1% of the human body weight as a component of bone, membrane, nucleic acids, and high-energy phosphates.…”

“…To synthesize P(III) chemicals from phosphates with reagents that are easy to handle, Cummins and co-workers now report the reduction of polyphosphates with potassium hydride under solvent-free conditions. 1 Grinding the polyphosphate/hydride mixture in a ball mill is the key to achieving a high yield of phosphite. The friction and impact generated during milling promote the reaction between solid polyphosphates and potassium hydride at room temperature that produces phosphite with good selectivity.…”

“…To synthesize P­(III) chemicals from phosphates with reagents that are easy to handle, Cummins and co-workers now report the reduction of polyphosphates with potassium hydride under solvent-free conditions . Grinding the polyphosphate/hydride mixture in a ball mill is the key to achieving a high yield of phosphite.…”