JPS6232759B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for removing triorganophosphines from an organic liquid containing an alkyl-substituted phosphine and a triarylphosphine by treating the liquid with phosphoric acid. More particularly, the present invention relates to a method for selectively removing alkyl-substituted phosphine from said liquid. A process for forming aldehydes involves reacting olefins with carbon monoxide and hydrogen under rhodium-trialkylphosphine complex catalysts in the presence of an excess of free triarylphosphine ligands to produce aldehydes enriched in normal isomers. , are well known in the industry, as can be seen, for example, from US Pat. No. 3,527,809 and Belgian Patent No. 853,377. Also, under the conditions of hydroformylation, some aldehyde products condense to form by-products such as It is also known that high boiling aldehyde condensation products such as aldehyde dimers and trimers can be formed which can act as solvents. Additionally, the presence of alkyldiarylphosphines (e.g., propyldiphenylphosphine or ethyldiphenylphosphine) in the rhodium-catalyzed hydroformylation of propylene inhibits the productivity of the catalyst, and the hydroformylation of α-olefins. When a triarylphosphine ligand is used in (same as the aryl of triarylphosphine) is also permitted. On the other hand, Belgian Patent No. 863267 teaches that the presence of such alkyldiarylphosphines can be compensated for by adjusting the hydroformylation conditions of the process, but does not produce aldehydes enriched in normal isomers. In continuous hydroformylation processes, the continuous generation of alkyl-substituted phosphine over a period of time will ultimately lead to an undesirable reduction in the reaction rate and rhodium complex catalyst based on the affinity of this alkyl-substituted phosphine for the rhodium catalyst. More recently, May 21, 1979 and
U.S. Patent Application Nos. 40913 and 108279, filed Dec. 28, 1979, disclose compositions containing rhodium complex hydroformylation catalysts or concentrates of such compositions, such as maleic acid or maleic anhydride. - Removal of triorganophosphines from said compositions or concentrates by treatment with unsaturated compounds or their acid anhydrides is disclosed. This method is particularly useful for selectively removing alkyl-substituted phosphine from the composition to restore the activity of rhodium complex catalysts. However, even after increasing the activity of the rhodium complex catalyst by removing the alkyl-substituted phosphine from the hydroformylation reaction medium, the rhodium complex catalyst eventually becomes obsolete (i.e., eventually becomes catalytically inactive). Activation procedures such as those described above cannot be repeated indefinitely, since the catalyst has been reduced to the point where it is no longer economically desirable to carry out the hydroformylation process), and the catalyst must be replaced. Furthermore, improper handling and/or contaminants etc. during the early stages of the hydroformylation process can lead to premature formation of undesirable hydroformylation media, which must also be replaced. Since the price of rhodium is extremely high, when the above phenomenon occurs, it is important to recover useful rhodium from the complex catalyst. Such recovery methods obviously involve loss and/or decomposition of organic compounds in the hydroformylation composition, which raises the question of how to deal with the large excess of triarylphosphines that must be removed from the catalyst solution. cause problems. For example, July 16, 1979 respectively.
and U.S. Patent Application No. 2, filed February 28, 1980.
No. 58123 and No. 120101 (all disclosures of which are incorporated herein by reference), the spent hydroformylation medium containing a rhodium complex catalyst is concentrated by distillation to perform hydroformylation with a rhodium complex. A method is disclosed for producing a rhodium complex concentrate that can be used as a source of reactivated rhodium for use in a process. Such processes produce organic liquid distillates containing alkyl-substituted phosphines and large excesses of triarylphosphines. Therefore, a process that can selectively remove alkyl-substituted phosphine and triarylphosphine-containing organic liquids would be clearly beneficial to the current state of the art. This is because such a method provides an excellent means for restoring the activity of spent rhodium complex catalysts or for recovering and obtaining large quantities of used triarylphosphines for reuse in hydroformylation processes. It is. It has now been discovered that by treating an organic liquid containing an alkyl-substituted phosphine and a triarylphosphine with phosphoric acid, the alkyl-substituted phosphine can be selectively removed from the organic liquid. Accordingly, it is an object of the present invention to provide a method for selectively removing alkyl-substituted phosphine from an organic liquid containing an alkyl-substituted phosphine and a triarylphosphine by treating the same with phosphoric acid. . Other objects and advantages of the invention will be readily apparent from the following description and claims. Therefore, from a general point of view, the present invention relates to the general formula (wherein R is an alkyl group, R' is an alkyl or aryl group, and R'' is an aryl group) In selectively removing an alkyl-substituted phosphine from an organic liquid, (1) triarylphosphine in and the above general formula ()
an organic liquid containing an alkyl-substituted phosphine and
(2) allowing the aqueous mixture of step _{( 1} ) to stand to form two distinct liquid phases; and (3) alkyl-substituted phosphine. separating an aqueous-acidic phase containing the solubilized protonated reaction product with phosphoric acid from the non-aqueous organic phase resulting from said steps (1) and (2), and said phosphorus used; It may be described as a process for the selective removal of alkyl-substituted phosphines in which the ratio of the volume of the aqueous acid solution to the volume of the organic liquid used is at least about 0.1 to 1. The organic liquid from which alkyl-substituted phosphine can be removed according to the present invention includes alkyl-substituted phosphine and triarylphosphine of the above general formula (),
And it can be any water-immiscible organic liquid free of contaminants that adversely affect the essential purpose of the invention. Preferably, the organic liquid comprises both of the above-mentioned phosphines by distilling a hydroformylation reaction medium or a derivative thereof containing both of the above-mentioned phosphines, such as those disclosed in the above-mentioned prior art; and by producing a distillate, the remainder of which is essentially a high-boiling aldehyde condensation by-product of the solvent and/or hydroformylation reaction medium. Therefore, the specific distillation operation for producing such organic liquid distillate is:
Obviously, this is not an important feature of the invention. This is because this operation serves only as a means to provide the organic liquid used as starting material for the present invention. However, in general,
Preferred organic liquids for use in the present invention have the general formula () obtained by the distillation and concentration operations outlined in U.S. Pat.
The distillate contains an alkyl-substituted phosphine and a triarylphosphine. The triarylphosphines present in the organic liquid used in the present invention can of course be any triarylphosphines suitable for use in hydroformylation reactions such as the triarylphosphines and reactions taught in the prior art mentioned above. It may be. Examples of triarylphosphines include triphenylphosphine, trinaphthylphosphine, tritolylphosphine, tri(p-biphenyl)phosphine, tri(p-methoxyphenyl)phosphine, p-(N·N-dimethyl Examples include amino)phenyldiphenylphosphine. Triphenylphosphine is a preferred triarylphosphine ligand. The alkyl-substituted phosphine present in the organic liquid used in the present invention can be any phosphine that is more basic than the triarylphosphine in the composition. For example, propyldiphenylphosphine (pKa = about 4.5-5.5) is more basic than triphenylphosphine (pKa = 2.73).
Examples of such alkyl-substituted phosphines include those defined by general formula () above. Additionally, as noted above, such alkyl-substituted phosphines are typically derived from certain hydroformylated olefins and certain triarylphosphines used in the hydroformylation process. For example, in the hydroformylation of propylene according to the preferred procedure described in Belgian Patent No. 853377, propyldiphenylphosphine as well as some detectable butyldiphenylphosphine are formed in situ. Dialkylarylphosphines, which are present as a result of in situ generation or separate addition to the hydroformylation process, are more basic than triarylphosphines, but can also be removed by the process of the invention. Thus, the alkyl group of the alkyl-substituted phosphine may be any alkyl group containing from 2 to 20 carbon atoms, preferably from 2 to 10 carbon atoms. These alkyl groups may be straight-chain or branched and may contain groups or substituents such as hydroxyl groups and alkoxy groups that do not essentially interfere with the process of the process of the invention. Examples of such alkyl groups include ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl,
Decyl, dodecyl, octadecyl, 2-ethylhexyl, eicosyl, 3-phenylpropyl, 3
-Hydroxypropyl, 4-hydroxyhexyl, 4-hydroxyoctyl, 2-ethoxyethyl, 2-methoxyethyl, 3-ethoxypropyl, and the like. Furthermore, since it is generally preferred to hydroformylate α-olefins containing 2 to 5 carbon atoms, the more preferred alkyl groups of the alkyl-substituted phosphine are ethyl, propyl, butyl and pentyl. Similarly, the aryl group of this alkyl-substituted phosphine may correspond to the aryl group of the triarylphosphine ligand used in the hydroformylation process, as described above. A preferred aryl group is a phenyl group derived from triphenylphosphine. The most preferred alkyl-substituted phosphines are ethyldiphenylphosphine, propyldiphenylphosphine and butyldiphenylphosphine, with propyldiphenylphosphine being particularly preferred. However, it is noted that there is no intention to define this invention by a precise discussion or explanation of how this alkyl-substituted phosphine is formed in situ. For the purposes of the present invention, it is merely pointed out that the in situ production of alkyl-substituted phosphines is possible and that such alkyl-substituted phosphines can be selectively removed when present in the organic liquid used. This is because it is sufficient. The purpose of the present invention is to selectively remove all or part of the alkyl-substituted phosphine in the organic liquid. Quantity is not important. moreover,
Since the preferred organic liquids of the present invention correspond to liquid distillates derived by concentrating the hydroformylation medium or its derivatives as described above, the amounts of triarylphosphines and alkyl-substituted phosphines are preferably: The distillate corresponds to the amount of alkyl-substituted phosphine present in the spent hydroformylation medium from which it was produced. Therefore, the amount of alkyl-substituted phosphine present in the organic liquid that can be used in the present invention is generally based on the total weight of the organic liquid.
The amount of triarylphosphine present in the organic liquid may range from about 1 to about 25% by weight, based on the total weight of the organic liquid.
It may be % by weight. Furthermore, the organic liquid of the present invention has at least 0.5
% by weight of alkyl-substituted phosphine, while
Preferably, the amount of triarylphosphine present is at least twice the amount of alkyl-substituted phosphine. It should also be understood, of course, that since this hydroformylation reaction is usually carried out in the presence of a solvent for the catalyst, it may also encompass the presence of such a solvent in similar amounts to the organic liquids used in the present invention. It is. Such solvents are well known in the art;
and high boiling liquid aldehyde condensation products as described in US Pat. No. 3,527,809 and more preferably as detailed in US Pat. No. 4,148,830.
Such condensation products can be preformed or formed in situ during the hydroformylation, and can also include complex mixtures of high-boiling liquid products of the hydroformylation processes described above. Accordingly, the amount of solvent and/or high boiling aldehyde condensation product present in the starting organic liquid feedstock of the present invention ranges from about 70 to about 98.9 parts by weight, based on the total weight of the liquid composition. It can take a range. Of course, it is to be understood that the organic liquids of the present invention may include the presence of minor amounts of other components such as phosphine oxide and the like. As mentioned above, preferred organic liquids of interest in the present invention are obtained by distilling the spent hydroformylation reaction medium or derivatives thereof containing both of the above-mentioned phosphines, such as alkyl-substituted phosphine, triarylphosphine and solvent and/or Such liquids are derived by producing a distillate consisting of high boiling aldehyde condensation by-products of the hydroformylation medium. Additionally, preferred distillation operations that can be used to produce such organic liquid distillates are detailed in the aforementioned US Patent Application Nos. 58,123 and 120,101. Such a distillation operation is preferably carried out in two stages. That is, the first stage is about 20~
Temperature of 250℃, preferably 20-190℃, about 1000℃ to approx.
The second stage distillation is carried out at a pressure of 0.1 mmHg, preferably about 150 to 0.5 mmHg, and the second stage distillation is carried out at a temperature of about 25 to 350°C, preferably about 150 to about 350°C, about 100 to 1×
The retentate or residual product of the first stage is further concentrated to the desired rhodium concentration by operating at a pressure of 10 ^-6 mmHg, preferably about 20 to 0.1 mmHg. The first distillation stage is used to distill off the most volatile components present in the spent hydroformyl medium, such as aldehyde products. These lower boiling volatile components are used in the second distillation stage and the desired lower pressures required to most effectively remove the lower volatile (i.e. higher boiling) components This is because it prevents you from obtaining. It is of course clear that the most volatile components thus removed (e.g. aldehyde products) may be conventionally recovered from this distillate stream or disposed of if desired. It is. The second distillation stage removes the liquid residue or bottoms of the first stage, which contains the partially inactivated rhodium complex catalyst and less volatile components of the spent hydroformylation reaction medium, such as solvent and phosphine ligands. and further subjecting this residual liquid to distillation under the above-mentioned reduced pressure to remove remaining high-boiling volatile substances. The most preferred organic liquid that can be used in the present invention is the distillate of the second distillation stage. Of course, this second distillation step may be carried out more than once if desired, so that the organic liquids usable in the present invention may of course include complex distillates of such continuous distillations. Furthermore, the distillation of each separation stage can be carried out using suitable distillation equipment and can be carried out continuously and/or batchwise. Generally, both distillation steps are carried out in a thin film evaporator, such as a wiped film or falling film evaporator;
Preferably, the second distillation stage is carried out under high vacuum. Such evaporators are well known in the art and therefore need not be discussed in detail here. As mentioned above, a 40-60 weight percent aqueous phosphoric acid solution can be used to selectively remove alkyl-substituted phosphine from the organic liquid starting material of the present invention. The method of the present invention involves first mixing an organic liquid starting material as described above with an aqueous phosphoric acid solution, then allowing the mixture to stand to form two distinct phases, and forming both an alkyl-substituted phosphine and a triarylphosphine. The aqueous-acidic (lower) phase containing the solubilized product of is separated from the organic liquid, ie non-aqueous upper phase, containing unreacted triarylphosphine and the remainder of the organic liquid starting material. The method of the present invention can be described as a method in which an organic liquid phosphine compound is reacted with phosphoric acid in the presence of water to produce an aqueous protonated phosphine. Additionally, although the invention is not limited to the above description with respect to the precise reaction order involved, it should be noted that alkyl-substituted phosphines and triarylphosphines are more basic and therefore more phosphoric than triarylphosphines. It was found that it was reactive to This difference in basicity is the basis for the selective removal of alkyl-substituted phosphines. Furthermore, for the purposes of the present invention,
It is sufficient to provide a method for selectively removing alkyl-substituted phosphines and is not constrained by discussion of the characteristic structure of the solubilized protonated reaction product. The reaction of the process of the invention is exothermic and therefore can be carried out at any suitable temperature. Furthermore, the method can be carried out under reduced pressure, normal pressure, or elevated pressure, as desired. Generally, the temperature is about 0
to about 150°C. Naturally, pressurization is required at temperatures of 100°C and higher. Preferably, the process is carried out at temperatures below 100°C under about normal pressure, more preferably between about 25°C and about 80°C.
It is ℃. It is important that the reactants involved are thoroughly mixed, and such mixing may be accomplished by conventional means, such as stirring. The general reaction is very rapid and is usually complete within one hour, more preferably within 30 minutes, based on the reactants, temperature and mixing efficiency. Since the process of the present invention is designed to selectively remove alkyl-substituted phosphines from organic liquid starting materials and is not a process for removing triarylphosphines, about 40 to about 60% by weight phosphorus An aqueous acid solution should be used. The amount of this aqueous solution used in the method of the invention is not strictly critical;
The amount may be sufficient as long as it is sufficient to solubilize the amount of the protonation reaction product between phosphines and phosphoric acid produced by the method of the present invention. However, the amount of water used should not be so great as to provide less than about 40% by weight aqueous phosphoric acid solution. This is because at such concentrations only very small amounts of alkyl-substituted phosphine can be extracted. Also, the amount of water should not be so small as to provide an aqueous phosphoric acid solution of about 60% by weight or more. This is because at such concentrations the co-extraction of triarylphosphines can be extremely high. Of course, some amount of triarylphosphine may, and undoubtedly will, be removed from the organic liquid starting material in the same manner as above (i.e., as a solubilized protonated reaction product with phosphoric acid). It is also clear that However, the process of the invention is designed to remove as much alkyl-substituted phosphine as possible from the starting organic liquid, while at the same time ensuring that very little triarylphosphine is removed from this liquid. Although at least about 0.1 volume equivalent of an aqueous phosphoric acid solution based on the weight of the organic liquid starting material to be treated can be used, it is generally preferred to use an equal volume of an aqueous phosphoric acid solution. Furthermore, to prevent excessive loss of triarylphosphine by oxidation to triarylphosphine oxide, the process of the present invention is preferably carried out in an inert atmosphere, such as nitrogen. Once the phosphine-phosphoric acid reaction of the process of the invention is complete, the mixture is allowed to settle into two distinct liquid phases. The lower phase is an aqueous-acidic phase containing the solubilized protonated reaction product of triorganophosphine and phosphoric acid;
It can be separated from the organic (i.e. non-aqueous upper) liquid phase, which contains unreacted organic liquid, by any suitable method, such as stripping the bottom layer or decanting the surface layer. This method is original in the following respects. That is,
If desired, the phosphoric acid is removed in the aqueous-acidic phase by neutralizing the aqueous-acidic phase with a suitable base, e.g. potassium hydroxide, and extracting the free phosphine into a suitable organic solvent, e.g. ethyl ether. The point is that the alkyl-substituted phosphine and triarylphosphine extracted by the method can be recovered. Alternatively, the alkyl-substituted phosphine can be removed from the aqueous-acidic phase by diluting it with enough water to such an extent that the phosphoric acid is no longer strong enough to protonate the alkyl-substituted phosphine and the phosphine separates. It can be recovered.
The free alkyl-substituted phosphine can then be extracted into any suitable organic solvent or collected by filtration as described above. More particularly, the method of the invention is particularly useful in the field of hydroformylation. This is because the process produces a distillate also containing large amounts of triarylphosphines, the remainder of which is essentially derived from the hydroformylation solvent and/or the high-boiling aldehyde condensation products of the hydroformylation medium as described above. This is because the alkyl-substituted phosphine is selectively removed from the distillate. The process of the invention is thus an original method for obtaining large quantities of triarylphosphines suitable for reuse in hydroformylation processes. However, for commercial operations the following method is recommended. That is, the (non-aqueous) organic liquid containing unreacted triarylphosphine obtained by the method of the present invention is thoroughly washed with a suitable alkaline aqueous solution such as sodium bicarbonate to remove any phosphoric acid that may be present. Then, before reusing the triarylphosphine in the hydroformylation process, it should be washed twice with water to completely remove the basic compound used in the first wash. The following examples are illustrative of the invention and are not intended to limit it. All parts, percentages and ratios in this specification and claims are by weight unless otherwise noted. Example 1 Treating a mixture of 1.8 area % propyl diphenylphosphine and 9.6 area % triphenylphosphine solution in Texanol, a mixture of butyraldehyde trimers, with different acids of similar strength. did. In each case, the solution mixture was stirred with an equal volume of an aqueous solution of the used acid at room temperature under nitrogen for about 30 minutes. The treated mixture was then allowed to stand to form two distinct liquid layers and the layers were separated. The (non-aqueous) organic layer was analyzed for phosphine. The results are shown in Table 1.

[Table] Example 2 Propyl diphenylphosphine (1.8 area%) and triphenylphosphine (9.2% by area) dissolved in Texanol, a mixture of butyraldehyde trimers.
The solution mixture (area %) was stirred with an equal volume of 60% phosphoric acid aqueous solution at room temperature under nitrogen for 30 minutes and allowed to stand to form two distinct liquid layers. The layers were separated and the (non-aqueous) organic layer was analyzed for phosphine. The same method as above was then repeated except that the solution mixture was stirred in air. The results obtained are shown in Table 1.

Table Example 3 A series of solutions containing various concentrations of propyldiphenylphosphine in concentrated phosphoric acid (approximately 85% by weight) were titrated with water at room temperature to the end point of turbidity. The weight percentages of the three components were calculated. The results are shown in Table 1.

Table: This three-layer diagram of the data shows that for the range of propyldiphenylphosphine studied, turbidity begins at phosphoric acid concentrations of 36-47%. Example 4 Example 3 was repeated using triphenylphosphine instead of propyldiphenylphosphine and the weight percentages of the three components were calculated. The results obtained are shown in Table 1. All final concentrations are the average of three measurements.

[Table] This data shows that for the concentration range studied, the precipitation of triphenylphosphine was
This indicates that this occurred in ~69% of cases. Example 5 A solution mixture containing 2.2 area % propyl diphenylphosphine and 9.6 area % triphenyl phosphine dissolved in Texanol, a mixture of butyraldehyde trimers, was heated under nitrogen with an equal volume of 60% aqueous phosphoric acid. The mixture was stirred at 25°C for about 30 minutes.
The mixture was allowed to stand to form two distinct layers.
The layers were separated and the (non-aqueous) organic layer was analyzed and found to contain 0.08 area % propyldiphenylphosphine and 8.2 area % triphenylphosphine. The aqueous-acidic layer was diluted with water and the phosphine contained in this layer was extracted with methylene chloride. The methylene chloride extract was analyzed by gas chromatography and was found to contain more than 99% of the propyl diphenylphosphine extracted from the original solution mixture. Example 6 Arthur F. Smith operated a hydroformylation reaction medium consisting of a rhodium complex catalyst, propyldiphenylphosphine, triphenylphosphine, and high-boiling aldehyde condensation byproducts at 230-240°C and 0.3-0.5 mm Hg. A distillate containing propyldiphenylphosphine and triphenylphosphine was obtained by passing it through a wiped thin film evaporator at a rate of about 3 g/min. The remainder of the distillate consisted essentially of high boiling aldehyde condensation by-products. A 50 ml sample of this distillate containing 6.7 g of triphenylphosphine and 0.46 g of propyl diphenylphosphine was stirred with 50 ml of 42% aqueous phosphoric acid at 30° C. for 35 minutes and allowed to stand to form two distinct liquid layers. did. The layers were separated and the (non-aqueous) organic layer was analyzed for phosphine and found to contain about 0.14 g of propyldiphenylphosphine and about 6.7 g of triphenylphosphine. The aqueous-acidic layer was neutralized with potassium hydroxide and the phosphine contained within the layer was extracted with ethyl ether. This ether extract was found to contain propyldiphenylphosphine and triphenylphosphine in a ratio of 8:1. Example 7 A hydroformylation reaction medium consisting of a rhodium complex catalyst, propyl diphenylphosphine, triphenylphosphine and a high boiling aldehyde condensation by-product was passed through an Arthur F. Smith wiped evaporator to produce triphenylphosphine. A distillate containing about 319 g and about 21.7 g of propyldiphenylphosphine and no rhodium was obtained. The remainder of the distillate consisted essentially of high boiling aldehyde condensation by-products. A portion of this distillate was thoroughly mixed with a 40% aqueous phosphoric acid solution at room temperature, and the mixture was allowed to separate into two distinct liquid layers. Separate these layers, and add the (non-aqueous) organic layer to 10
% aqueous sodium bicarbonate solution and then water. After removing the water, the washed organic liquid was diluted with Texanol, a mixture of butyraldehyde trimers, to give an organic solution containing about 4.8% by weight of triphenylphosphine. A rhodium complex compound was then added to this solution resulting in a rhodium concentration of approximately 300 ppm. A 15 ml portion of this solution was charged to a stirred pressure cooker and heated to 100°C under nitrogen. The nitrogen was vented and the reaction kettle was charged with propylene, carbon monoxide, and hydrogen in a 1:1:1 molar ratio to a pressure of about 80 psig to hydroformylate the propylene to form butyraldehyde. The propylene hydroformylation reaction rate was 0.996 g·mol/·hr. Using this raw distillate under the same conditions but without pretreatment with phosphoric acid, sodium bicarbonate, and water to produce the hydroformylation medium as above, the hydroformylation rate was approximately
It was 0.585 g·mol/·hr. Washing this distillate with base alone had little effect on the hydroformylation reaction rate. Furthermore, a new rhodium-catalyzed hydroformylation solution prepared using a new triphenylphosphine showed a propylene hydroformylation rate of 1.06 g.
mol/・time was obtained. Example 8 Contains about 2.0% by weight of propyldiphenylphosphine and about 22.4% by weight of triphenylphosphine,
A distillate sample containing no rhodium and the remainder consisting essentially of high-boiling aldehyde condensation by-products,
Mixed with equal volumes of either phosphoric acid or sulfuric acid aqueous solutions of different strengths for about 25-30 minutes at room temperature. This sample was obtained by wiping off the hydroformylation medium of the rhodium complex catalyst and distilling it in a thin film evaporator. The treated mixture was then allowed to stand into two distinct liquid layers, and the layers were separated. The (non-aqueous) organic layer was analyzed for phosphine, and the results are shown in Table 1.

[Table] Example 9 A certain amount (100 ml) of rhodium complex catalyst hydroformylation medium that had been batch-distilled to remove aldehydes was analyzed, and approximately 488 ppm of rhodium,
It was found to contain about 0.85% by weight propyldiphenylphosphine and about 14.6% by weight triphenylphosphine. 100ml of the above fixed amount sample
The mixture was stirred at 25°C with aqueous phosphoric acid solutions of 20, 40, 60 and 80% by weight. The samples taken after different contact times were made into two different liquid phases and then the phases were separated. The organic (non-aqueous) layer was analyzed for phosphine and rhodium, while the aqueous-acidic layer was analyzed only for rhodium. The results are shown in the table below.

【table】

TABLE Many modifications of this invention will be apparent to those skilled in the art and are clearly within the scope of this invention.

Claims (1)

[Claims] 1. General formula (wherein R is an alkyl group, R' is an alkyl or aryl group, and R'' is an aryl group), an alkyl-substituted phosphine of the above general formula and a triarylphosphine are combined. (1) mixing said organic liquid with an aqueous solution of about 40-60% by weight phosphoric acid; (2) allowing the mixture to stand to form two distinct liquid phases; and (3) ) separating an aqueous-acidic phase containing the protonated reaction product of said phosphine and said phosphoric acid resulting from steps (1) and (2), and determining the volume of said phosphoric acid aqueous solution used versus the volume of said phosphoric acid solution used. 2. The method of claim 1, wherein the ratio of volumes of the organic liquid is at least about 0.1 to 1. 2. The method of claim 1, wherein the triarylphosphine is triphenylphosphine. 3. Alkyl-substituted phosphine. The method according to claim 2, wherein the phosphine is selected from the group consisting of ethyldiphenylphosphine, propyldiphenylphosphine, and butyldiphenylphosphine. 4. The method according to claim 2, wherein the alkyl-substituted phosphine is propyldiphenylphosphine. 5. The method according to claim 4, in which phosphoric acid is used in the form of an approximately 60% by weight phosphoric acid aqueous solution. 6) The method in claim 4, in which phosphoric acid is used in the form of approximately 40% by weight phosphoric acid aqueous solution. 7. The organic liquid is a distillate of a rhodium complex catalyst comprising a hydroformylation medium or a derivative of said distillate comprising an alkyl-substituted phosphine and a triarylphosphine of the general formula; 8. The method of claim 1, wherein the remainder of the distillate consists essentially of high-boiling aldehyde condensation by-products.8. 9. The method according to claim 7, wherein enylphosphine is used. 9. The method according to claim 8, wherein the phosphoric acid aqueous solution and the organic liquid are used in approximately equal volumes.