US3397038A - Manufacture of a reactive trisodium phosphide - Google Patents

Description

United States Patent O 3,397,038 MANUFACTURE OF A REACTIVE TRISODIUM PHOSPHIDE Alfred O. Minklei, Kenmore, N.Y., and Hans Z. Lecher,

Plainfield, N.J., assignors to Hooker Chemical Corporation, Niagara Falls, N.Y., a corporation of New York No Drawing. Filed Nov. 30, 1964, Ser. No. 414,889 9 Claims. (Cl. 23-204) ABSTRACT OF THE DISCLOSURE A process for producing alkali metal phosphides by reacting a finely divided alkali metal with phosphorus at low temperatures in the presence of a polycyclic aromatic hydrocarbon and an activating ether solvent.

This invention relates to the preparation of alkali metal phosphides and the utilization of such alkali metal phosphides in the preparation of phosphorus compounds.

It has heretofore been proposed to prepare alkali metal phosphides by the reaction of phosphorus with the corresponding alkali metal at temperatures in the range of 750 degrees centigrade to 1,000 degrees centigrade.

An object of this invention is to prepare a reactive alkali metal phosphide by a low temperature process. Other objects of the invention will be apparent from the following description.

Ithas now been discovered that alkali metal phosphides can be made by the low temperature reaction of phosphorus with a finely divided alkali metal activated by a polycyclic aromatic hydrocarbon and an ether solvent. The reaction product may thereafter be hydrolyzed by suitable hydrolyzing agents or it may be reacted with organic reactive halides to obtain the corresponding phosp'hines and corresponding phosphonium compounds.

Unexpectedly, the process of this invention yields highly reactive alkali metal phosphides. Additionally, it provides a novel method for their preparation. The reaction of phosphorus and an alkali metal does not proceed at low temperatures, while at elevated temperatures it produces alkali metal phosphides which are unreactive towards organic halides and hydrolyze to yield phosphine contaminated by diphosphine. The alkali metal phosphides of this invention react readily with organic halides and hydrolyze to produce substantially pure phosphine.

In carrying out the process of this invention the alkali metal is first dispersed in an inert liquid hydrocarbon dispersion medium boiling above the melting point of the alkali metal. Examples of suitable media are toluene, xylene, mineral oil and the like. Dispersion of the alkali metal may be accomplished by any suitable means. Generally, a device capable of imparting high shear, e.g., a rotating impeller, a dispersator and the like, operating at a temperature which is maintained above the melting point of sodium, 97.5 degrees centigrade, but below the boiling point of the inert medium, may be effectively employed. A convenient temperature to effect the dispersion may be in the range of 100 degrees centigrade to about 115 degrees centrigrade, but temperatures from 100 to 300 degrees Centigrade are useful. The dispersed alkali metal particles may have a diameter in the range of from 0.2 micron to 60 microns. It is preferred to prepare particles in the range of 0.5 micron to 40 microns and.

the most preferred are particles in the range of 0.5 micron to 20 microns in diameter. Upon completion of the dispersion, which may take from 0.5 to 20 minutes of mixing, the dispersion medium is drained off. It is within the scope of this invention to employ the activating solvent, described below, instead of the liquid hydrocarbon dispersion medium.

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A solvent mixture comprising an activating solvent selected from the preferred group consisting of alkyloxy ethers and cyclic ethers, and a minor proportion of an aromatic hydrocarbon selected from the group consisting of condensed polycyclic hydrocarbons and noncondensed polycylic aromatic hydrocarbons is then added to the alkali metal dispersion. It is apparent that under certain conditions, i.e., where the activating solvent described above is employed as a dispersion medium, only a minor proportion of the aromatic polycyclic hydrocarbon catalyst may be added to the dispersed alkali metal. White or yellow phosphorus may then be added to the reaction mixture according to one of the following techniques: under inert conditions, e.g., under a nitrogen atmosphere; dissolved in a suitable solvent such as toluene, xylene, mineral oil, and the like; molten and added in a phosphorus carrier or vehicle such as tetrahydrofuran or toluene; or employing any other suitable method. Red phosphorus cannot be used. Upon completion of the reaction, the alkali metal phosphide may be separated from the mixture by filtration, or other solid-liquid separation technique, or it may be reacted directly with an appropriate reactant to produce the desired phosphorus compound. It is to be understood that the process can be carried out batchwise, intermittently or continuously. Further, it is to be understood that the invention is not limited to any particular type of reactor for there are several convenient apparatuses for effecting the process of this invention.

The alkali metals employed in the practice of this invention are potassium, sodium, lithium, rubidium and cesium. The preferred alkali metal is sodium.

As to the condensed polycyclic aromatic hydrocarbons, there can be used the condensed polycyclic aromatic hydrocarbons having 10 to about 32 carbon atoms, the most preferred of these have 10 to 15 carbon atoms. Typical examples of these include naphthalene, anthracene, phenanthrene and the like. Of these, it has been found that naphthalene is particularly suitable. In addition, non-condensed polycyclic aromatic hydrocarbons having from 12 to about 32 carbon atoms may also be employed effectively in the process of this invention. The most preferred of these have 12 to 19 carbon atoms. Typical examples of these are: biphenyl, terphenyl, dinaphthyl, and the like.

Generally, the ethers used as activating solvents may be cyclic ethers having from 4 to about 12 carbon atoms, the most preferred of these have 4 to 8 carbon atoms. Typical examples of these are: tetrahydrofuran and dioxane. Of these, it has been found that tetrahydrofuran is particu larly useful. Additionally, the ethers may be the alkyloxy ethers having from 2 to about 20 carbon atoms. The most preferred of these have 2 to 12 carbon atoms and contain at least one methoxy group. Examples of these are dimethyl ether of diethylene glycol, dimethyl ether of triethylene glycol, dimethyl ether of tetraethylene glycol and the like. It is also within the scope of this invention to employ alkylated glycols and polyhydric alcohols.

Sufficient activating solvent is employed to provide a convenient reaction mixture. Amounts in the range of 50:1 to about 200:1 based upon phosphorus have been satisfactorily employed. However, greater or lesser amounts of the activating solvent may be added, as desired.

The aromatic polycyclic hydrocarbon catalyst is utilized in molar ratios based on sodium employed. A molar ratio of aromatic hydrocarbon to sodium which may be utilized is in the range of 120.1 to about 1:80, the more preferred being 1:05 to 1:40 and the most preferred being 1:1 to 1:15 on the basis mentioned.

Advantageously, the reaction of sodium, dispersed in the solvent mixture, and phosphorus may be effected at temperatures ranging from about 10 degrees centigrade to 150 degrees centigrade, a preferred range being 20 degrees centigrade to 100 degrees centigrade, and the 4 Examples 1-15 The reactants, conditions and results of these examples are set forth in Table I. The procedures followed are most preferred is a range of 30 degrees centigrade to 5 hereinafter-described. In a reactor Vessel, an alkali metal 75 degrees centigrade. Further, the process of this indlspefsed uslng a q p Q and dlspelslon vention may be carried out at superatmospheric pressures, med111111- when The dlspefslofl Ihedwm Was not 9 that atmospheric pressures and subatmospheric pressures. could also be used as an activating solvent, the dlspersed Phosphorus is added to the reaction mixture in the alkali metal was drained off. Subsequently, if required, process of the invention in an amount substantially stoi- 10 the activating solvent was added to the dispersion, and, chiometrically equivalent to the sodium employed. 111 turn, the r atic polycyclic hydrocarbon was added The product of the heretofore described process may the resultlng mlXtuTe- Thereafter, Phosphorus Was be hydrolyzed to produce phosphine. It is to be underintroduced to the mixture and reacted therewtih.

TABLE I Example No 1 2 3 4 5 6 7 8 9 10 ll 12 13 14 15 Variables:

Reaction time, hours 4.3 1.0 1. 2.25 0.5 1.0 4.22 0.25 2.5 0.0 2.5 2.0 3.5 0.33 Reaction tern erature,

degrees centigr de -72 -71 5570 55 50-70 43-72 41-70 40-70 07-72 20-32 135 130 101 101 101 White phosphorus addition time, hours 0.5 0.5 0.66 1.0 0.12 0.92 0.3 Sodium particles,microns 0.5-2 05-20 0. 5-20 0. 5-20 0.5-20 0.5-20 0. 5-20 0.5-20 0.5-20 0. 5-20 0.5-20 0. 5-20 0.5-20 0. 5-20 0.5-20 Sodium/Naphthalene,

moles 5. 5 11 11 56 56 28 12 6. 8 11 5. 6 5, 6 5 6 Phosphorus Materials in (Parts by Weight):

Sodium, parts 5.02 5. 02 5.02 5. 02 5. 02 5. 02 5. 02 5. 02 5. 02 5. 02 5. 02 5.02 5. 2 5,02 Phosphorus, parts 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2 2 2.2 Naphthalene, parts 5 0 Tetrahydroturan, parts Anthracene, parts Biphenyl, parts Dioxanepal'ts 129.1 77.5 77 5 Diethyl ether of diethylene glycol, parts 300 300 Yield NaaP (percent), based on phosphorus 47 76 90 88 86 83 82 90 00 72 54 75 91 s5 83 Dissolved in 108.25 parts of toluene.

b Molten phosphorus under 13.3 parts of tetrahydroiuran or 12.9 parts of li cihed over a two-minute period. stood that various hydrolyzing agents may be utilized. Examples of hydrolyzing agents include: water, alcohols, which may be employed in aqueous solutions, aqueous inorganic hydrolyzing agents and aqueous organic hydrolyzing agents. The rate at which the hydrolyzing agent is added to the reaction product of this invention may vary considerably. However, by way of example, it may be desirable to add the hydrolyzing agent in an aqueous solution dropwise or in a steady stream.

In addition, the product of the above-described process may be reacted with organic reactive halides selected from the group consisting of alkyl and substituted alkyl halides having 1 to 20 carbon atoms, the preferred having 1 to 10 carbon atoms; alkenyl and substituted alkenyl halides having 1 to 20 carbon atoms, the preferred having 1 to 10 carbon atoms; and aralkyl and substituted aralkyl halides having 6 to 18 carbon atoms, the preferred having 6 to 12 carbon atoms. Examples of these compounds are methyl chloride, butyl chloride, ethyl chloride, chloroacetonitrile, allyl chloride, benzyl chloride, methyl bromide, benzyl iodide, propyl iodide, ethyl bromide, allyl bromide, and the like.

The reaction of the organic halide and the alkali metal phosphide may be effected at temperatures in the range of 0 degree centigrade to about 100 degrees centigrade, but temperatures from 0 degree centigrade to 200- degrees centigrade are useful.

It is within the scope of this invention to effect the organic halide reaction as a step in the preparation of the alkali metal phosphide, whereby the need for the separation of alkali metal phosphide is eliminated. The recovery of the organic phosphorus compound, produced by the reaction, may be accomplished by any suitable phase separation method, such as fractionation and the like. i

The following examples are given to illustrate the present invention and are not intended to limit the scope of the invention in any way. All temperatures are in degrees centigrade, and weights are in parts, parts are by weight, unless otherwise specified.

d Dissolved in 116.9 parts of toluene. Molten phosphorus under an atmosphere of nitrogen. t From completion of phosphorus addition.

In Examples 1, 2, 3 and 4, phosphorus was dissolved in toluene and added to the reaction mixture comprising sodium and solvent; in Examples 5, 6, 7 and 8, molten phosphorus under tetrahydrofuran or toluene was added to the reaction mixture; in Examples 9 and 10, phosphrous was dissolved in toluene and added to the reaction mixture; and Examples 11, 12, 13, 14 and 15, molten phosphorus, under an atmosphere of nitrogen, was added to the reaction mixture.

Examples 9 and 10, show the results obtained using hydrocarbons such as anthracene and biphenyl, in place of naphthalene. The mole ratios of alkali metal to hydrocafbon were effectively varied and produced efiicient resu ts.

Various ethers were used such as tetrahydrofuran, dioxane and dimethyl ether of diethylene glycol.

It is significant to note that temperatures in the range of 25 degrees centigrade and degrees centigrade were successfully employed.

Examples 11, 12, 13, 14 and 15, dispensed with the use of hydrocarbyl dispersion medium for sodium and avoided the subsequent draining of said medium. Dioxane and dimethyl ether of ethylene glycol were substituted and produced satisfactory results. When another alkali metal such as potassium, lithium, rubidium or cesium is used in place of sodium, similar results are obtained.

EXAMPLE 16 A reactor vessel was charged with 5.02 parts of sodium previously dispersed in 217 parts of toluene and drained of the excess solvent, so as to produce sodium particles in the range of 0.5 micron to 20 microns, and 355 parts of tetrahydrofuran containing 2.50 parts of naphthalene (1.0 molar proportion). The mixture was heated to 55 degrees centigrade, at which point 2.2 parts of phosphorus dissolved in 108 parts of toluene were added to the stirred suspension over a period of 0.66 hour. The mixture was stirred at 74 degrees centigrade for an additional 1.25 hours. Thereafter, the resulting trisodium phosphide was hydroylzed with water at 70 degrees centigrade, and

the evolved phosphine was measured by absorption in sodium hypobromite.

EXAMPLE 17 A typical reaction involving trisodium phosphide, prepared by the process of this invention, and an aralkyl halide is illustrated. A reaction vessel was charged with 7.1 parts of trisodium phosphide (1.0 molar proportion), prepared in tetrahydrofuran. The mixture was heated to 71 degrees centigrade and 27.8 parts of benzyl chloride (3.0 molar proportions) were added to the stirred suspension over a period of 0.5 hour. The mixture was then agitated for an additional 3.33 hours at 73 degrees centigrade. After the reaction was complete, the excess trisodium phosphide was filtred from the mixture and hydrolyzed with water. The water and organic layers were separated and the organic layer was distilled off. The residue in the reactor was subjected to successive recrystallizations, whereupon a solid with a melting point of 222.5 to 224 degrees centigrade was recovered. Literature value for melting point of tetrabenzyl phosphonium chloride is 225 degrees centigrade.

EXAMPLE 18 A typical reaction involving trisodium phosphide and an alkyl halide is disclosed by this example. .A reaction vessel 'was charged with parts of sodium particles having a diameter in the range of 0.5 micron to 20 microns dispersed in toluene. The solvent toluene was drained off and 199.2 parts of tetrahydrofuran containing 10.0 parts of naphthalene was added. To this mixture were added 8.8 parts of phosphorus dissolved in toluene and refluxed for a few hours. Upon completion of the reflux, 62 parts of ethyl chloride were added to the mixture which was maintained at zero degrees centigrade. After standing overnight, the mixture had a layer of solids on the bottom with clear liquid on top. No phosphine was evolved when water was added to dissolve the salt formed. The organic layer was separated and distilled. The analysis of the residue was 17.2 percent of phosphrous, indicating the formation of tetraethylphosphonium chloride. When the phosphonium compound is subjected to dry distillation, at temperatures above 200 degrees and in vacuo, the corresponding phosphine is produced.

EXAMPLE 19 A reaction vessel was charged with 7.1 parts of trisodium phosphide (1.0 molar proportion) suspended in 355 parts of tetrahydrofuran and 108 lparts of toluene. To the mixture, maintained at 70 degrees centigrade, were added 26.5 parts of butyl chloride (3.0 molar proportions). Completion of the reaction was evidenced by the absence of phosphine when water was added.

EXAMPLE 20 The procedure of Example 19 was repeated, replacing the butyl chloride with 20.1 parts of methyl chloride (4.8 molar proportions) and added over a period of 0.88 hour. Water hydrolysis of the reaction mixture indicated that 84 percent of the trisodium phosphide had reacted. When another organic halide such as methyl bromide, propyl iodide, allyl bromide and the like is used in place of butyl chloride, similar results are obtained.

While there have been described various embodiments of the invention, the compositions and methods described are not intended to limit the scope of this invention, it being realized that changes therein and substitution of equivalents are possible. It is further intended that each element recited in any of the following claims is to be understood as referring to all equivalent elements for accomplishing substantially the same results in substantially the same or equivalent manner, the claims covering the invention broadly in whatever from its principle may be utilized.

What is claimed is:

1. A process for preparing an alkali metal phosphide comprising reacting phosphorus with a finely divided alkali metal dispersed in a solvent containing an aromatic polycyclic hydrocarbon.

2. A process for preparing an alkali metal phosphide comprising reacting phosphorus with a finely divided alkali metal dispersed in a solvent mixture comprising an activating ether solvent and an aromatic polycyclic hydrocarbon, and separating the alkali metal phosphide from the reaction mixture.

3. A process in accordance with claim 2 wherein the dispersed finely divided alkali metal comprises particles having a diameter in the range of 0.2 micron to 60 microns.

4. A process for preparing an alkali metal phosphide comprising dispersing a finely divided alkali metal in a liquid hydrocarbon dispersion medium boiling above the melting point of the alkali metal, removing the excess dispersion medium therefrom, adding a solvent mixture comprising an activating ether solvent and a minor proportion of an aromatic polycyclic hydrocarbon to the remaining dispersion, and introducing phosphorus to said reaction mixture in an amount substantially stoichiometrically equivalent to the sodium employed, while maintaining the reaction temperature in the range of 10 degrees centigrade to 150 degrees centigrade.

5. A process for preparing an alkali metal phosphite comprising reacting phosphorus with a mixture which comprises alkali metal particles in the range of 0.2 micron to about 60 microns and a solvent mixture comprising an activating ether solvent selected from the group consisting of alkyloxy ethers and cyclic ethers, and a minor proportion of an aromatic hydrocarbon selected from the group consisting of condensed polycyclic hydrocarbons and noncondensed polycyclic aromatic hydrocarbons, maintaining the reaction temperature in the range of 10 degrees centigrade to 150 degrees centigrade, and separating the alkali metal phosphide formed.

6. A process in accordance with claim 5 wherein the dispersed alkali metal is in the form of particles having a diameter in the range of 0.5 micron to 20 microns.

7. A process for preparing an alkali metal phosphite comprising reacting phosphorus with a mixture which comprises alkali metal particles in the range of 0.5 micron to 20 microns and a solvent mixture comprising a cyclic ether and a minor proportion of a condensed polycyclic hydrocarbon having 10 to 15 carbon atoms, maintaining the reaction temperature in the range of 10 degrees centigrade to 15 0 degrees centigrade, and thereafter separating the alkali metal phosphide formed.

8. A process in accordance with claim 7 wherein the naphthalene is used in a molar proportion of 1:1 to 1:15 based on sodium employed.

9. A process for preparing trisodium phosphide comprising reacting phosphorus with a mixture which comprises sodium particles in the range of 0.5 micron and 20 microns and a solvent mixture comprising tetrahydrofuran and a minor proportion of naphthalene, maintaining the reaction temperature in the range of 30 degrees centigrade to degrees centigrade and thereafter separating the trisodium phosphide formed.

References Cited UNITED STATES PATENTS 7/1965 Best 26093.7

OTHER REFERENCES OSCAR R. VERTIZ, Primary Examiner.

H. S. MILLER, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,397,038 August 13, 1968 Alfred O. Minklei et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

"phosphrous" each Column 4, line 40 and column 5, lines 39 and 40,

lines 26 and 42,

occurrence, should read phosphorus Column 6, "phosphite", each occurrence, should read phosphide Signed and sealed this 31st day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer