Method of conversion of red phosphorous to soluble polyphosphides
Soluble polyphosphides were successfully generated in a number of organic solvents by a reaction between shelf-stable red phosphorus and potassium ethoxide or other nucleophilic activators. The species were identified by 31 P-NMR in solution. The reaction was scaled up to gram quantities by using a flow-chemistry process.
1. A method for producing polyphosphide anions soluble in organic solvents, comprising:
providing red phosphorus or a composition of black phosphorus and red phosphorus;
providing an alkali metal alkoxy compound or alkali metal alkyl thiolate compound suspended in an organic solvent;
wherein the alkali metal is sodium or potassium;
allowing the red phosphorus and alkali metal or alkali metal compound to react, wherein the reaction uses reflux or an in-line packed column method;
where the in-line packed column method comprises:
providing a packing column;
loading the packing column with the red phosphorus or composition of black phosphorus and red phosphorus in an inert environment;
purging the packing column with an inert gas;
setting a pressure regulator on the packing column to at least 1 bar;
heating the packing column to a preselected temperature, where the preselected temperature is at least the boiling point of the alkali metal alkoxy compound or alkali metal alkyl thiolate;
suspending the alkali metal alkoxy compound or alkali metal alkyl thiolate compound in the organic solvent;
flowing the organic solvent through the packing column;
flowing the alkali metal alkoxy compound or alkali metal alkyl thiolate compound in the organic solvent through the packing column; and
forming a compound containing the alkali metal and polyphosphide anions.
2. The method of claim 1 , wherein the alkali metal alkoxy compound or alkali metal alkyl thiolate compound is potassium ethoxide, potassium methoxide, sodium ethoxide, sodium methoxide, or sodium methyl thiolate.
3. The method of claim 1 , wherein the organic solvent is methyl cyanide, dimethyl sulfoxide, dimethylformamide, or a combination of tetrahydrofuran and dimethoxyethane.
4. The method of claim 3 , wherein the combination of tetrahydrofuran and dimethoxyethane is at a volume to volume ratio of 1:1.
5. The method of claim 1 , wherein the reflux is performed for about 15 minutes to about 2 hours.
6. The method of claim 1 , wherein the organic solvent is evaporated off the compound containing the alkali metal and polyphosphide anions.
7. The method of claim 6 , further comprising redissolving the compound containing the alkali metal and polyphosphide anions in ethanol.
8. The method of claim 7 , further comprising:
subjecting the compounds containing alkali metal and polyphosphide anions to a cation exchange with (Bu 4 N)Cl in ethanol to produce a cation-polyphosphide material; and
redissolving the cation-polyphosphide material in acetonitrile to form free polyphosphide anions.
9. The method of claim 8 , wherein the free polyphosphide anions are P 5 − , P 16 2− , P 21 3− , or a combination thereof.
10. The method of claim 1 , wherein the red phosphorus has a grain size of about 1.4 mm to about 0.7 mm.
11. The method of claim 1 , wherein the packing column is stainless steel, cast aluminum, A10 aluminum, A12 aluminum, stainless steel, aluminum-nickel alloy (50-50), polyimide, polyethylene terephthalate, polyamide-imide, nylon, polyvinyl chloride, polycarbonate, polyphthalamide, polysulfone, maleimide/bismaleimide, polyetheretherketone, polyetherimide, polyimide, polyester, acrylonitrile butadiene styrene, carbon reinforced-polyimide, carbon reinforced-polyethylene terephthalate, carbon reinforced-polyamide-imide, carbon reinforced-nylon, carbon reinforced-polyvinyl chloride, carbon reinforced-polycarbonate, carbon reinforced-polyphthalamide, carbon reinforced-polysulfone, carbon reinforced-maleimide/bismaleimide, carbon reinforced-polyetheretherketone, carbon reinforced-polyetherimide, carbon reinforced-polyimide, carbon reinforced-polyester, carbon reinforced-acrylonitrile butadiene styrene, glass reinforced-polyimide, glass reinforced-polyethylene terephthalate, glass reinforced-polyamide-imide, glass reinforced-nylon, glass reinforced-polyvinyl chloride, glass reinforced-polycarbonate, glass reinforced-polyphthalamide, glass reinforced-polysulfone, glass reinforced-maleimide/bismaleimide, glass reinforced-polyetheretherketone, glass reinforced-polyetherimide, glass reinforced-polyimide, glass reinforced-polyester, or glass reinforced-acrylonitrile butadiene styrene.
12. The method of claim 11 , wherein the packing column is stainless steel and wherein the preselected temperature is at least 80° C.
13. The method of claim 11 , wherein the stainless steel packing column is pressurized to about 8 bar.
14. The method of claim 1 , wherein the packing column has an internal diameter of about 9 mm and a length of about 65 mm.
15. The method of claim 14 , wherein the alkali metal alkoxy compound or alkali metal alkyl thiolate is flowed through the packing column at a rate of about 0.5 mL min −1 .
16. The method of claim 1 , wherein the temperature of the packing column or a reaction solution does not exceed the critical temperature of the organic solvent.
17. The method of claim 1 , further comprising separating the black phosphorus from the polyphosphide anions.