DE1518590C - Process for the separation of small amounts of tertiary phosphines from olefinic compounds - Google Patents

Description

The invention relates to a process for separating off small amounts of tertiary phosphines of the general type Formula I.

(i)

araliphatic or aromatic hydrocarbon radicals with 1 to 8 carbon atoms, preferably the phenyl group, mean, of olefinic compounds of the general formula

Rt \ / Rö

C = C

in which R ₁ , R ₂ and R _{3 are} aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radicals having 1 to 8 carbon atoms, preferably the phenyl group, of olefinic compounds of the general formula II

R ₄ V / ^ ⁶

C = C (II)

K ₅ K ₇

in which R ₄ , R ₅ , R ₆ and R ₇ denote hydrogen or saturated or unsaturated aliphatic, cycloaliphatic, araliphatic or aromatic radicals, the total number of carbon atoms in the compound of the general formula II being at least 8 and where R ₄ and R ₅ and R ₆ and R _{7 can} each be linked to form a 5- to 8-membered ring.

While larger amounts of the phosphines of the general formula I from the olefinic compounds can remove by distillation, extraction or crystallization, it is extremely difficult to without too much technical effort on these 30; Way smaller amounts of the phosphines from the to separate olefinic compounds.

The problem with olefinic compounds is similar, if not quite as difficult of the general formula II of tertiary phosphine oxides of the general formula III

R ₅ '

in which R ₄ , R ₅ , R ₆ and R _{7 are} hydrogen or saturated or unsaturated aliphatic, cycloaliphatic, araliphatic or aromatic radicals, the total number of carbon atoms should be at least 8 and where R ₄ and R ₅ and R ₆ and R _{7 can} each be connected to form a 5- to 8-membered ring, is characterized in that water-insoluble organic solutions of the mixtures of the tertiary phosphines of the above general formula and the olefinic compound are treated with aqueous solutions of peroxides and the tertiary phosphine oxides formed in this process general formula

P = O

P = O

(III)

40

to free.

It is z. B. from the German Auslegeschrift 1 068 710 known that the solution of an olefinic A compound of the vitamin A series, which is contaminated with a phosphine oxide, in a water-insoluble one lipophilic, non-polar or slightly polar organic solvent with a water-soluble one lipophobic polar solvent can extract, however, the total phosphorus in the then separated olefinic compound not to as low as 0.01%> reduce. Even when this method is applied to other olefinic compounds of the general formula II one cannot achieve such low phosphorus levels in the olefinic compound.

It has now been found that it is nevertheless possible to use olefinic compounds of the general formula II with such low phosphorus levels to be won. The inventive method for separation small amounts of tertiary phosphines of the general formula

65

in which R ₁ , R ₂ and R _{3 are} aliphatic, cycloaliphatic,

in which R ₁ , R ₂ and R ₃ are as defined above, either in a conventional manner or by extraction of the solution of the phosphine oxide in a non-polar or slightly polar, water-insoluble, lipophilic solvent with a water-soluble, lipophobic, polar solvent.

The cleaning method according to the invention is primarily suitable for removing that in the art especially in the Wittig synthesis serving as a reactant triphenylphosphine of the here obtainable olefinic compounds, but also to remove the other tertiary phosphines with the residues as defined, e.g. B. of tritolylphosphines, triethylphosphine, triisopropylphosphine, Tricyclohexylphosphine and of phosphines with different residues, such as Diphenyltolylphosphinen or diphenylxylylphosphines.

These tertiary phosphines of the general formula I can, for. B. be separated from the following olefinic compounds: linalool, dehydrolinalool, α-ion, vitamin Ai acetate or palmitate, vitamin Αχ-acid ethyl ester, vitamin Ai-aldehyde, vitamin A ₂ acetate, vitamin A ₂ - ethyl acid ester, axerophthene, / 3-apo-12'-carotinal, / J-apo-li'-carotinol acetate, / S-apo-12'-carotinic acid ethyl ester, /? - apo-8'-carotinal, ß-apo- 8'-carotinol acetate, ß-apo-S'-carotinic acid ethyl ester, α-carotene, ^ -carotene, lycopene, farnesylacetone and isophythol.

In general, the olefinic compounds can either be pure hydrocarbons or one or two ester or ether groups or nitrile, carbonyl or hydroxyl groups in the molecule contain.

According to previous observations, the success of the method according to the invention is not here depends on the chemical constitution.

The process for the pure preparation of compounds is of particularly great technical importance, which must be free of physiologically harmful impurities according to their determination, z. B. of fragrances, vitamin A and its derivatives

and carotenoid series food colors. Here, the phosphorus content can be easily determined decrease to 0.01 and below.

Suitable water-insoluble organic solvents for the mixtures of phosphine and olefinic Compound, which usually also contain phosphine oxide, are preferred in terms of extractive Separation of the phosphine oxide, especially aliphatic hydrocarbons with 5 to 25 carbon atoms, such as petroleum ether, light gasoline, ligroin, octane, isooctane, gasoline, paraffin oils, and also cycloaliphatic oils Hydrocarbons such as cyclohexane and cyclooctane; aromatic hydrocarbons such as benzene and toluene; halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and carbon tetrachloride. Homogeneous mixtures of these solvents are also suitable.

Appropriately, 0.1 to 30% solutions of the to be cleaned are made with these solvents Substance.

Suitable peroxides are inorganic or organic compounds with a (- O - O - ^ group, like - hydrogen peroxide, sodium peroxide, '"> Caro's acid, persulphuric acid, peracetic acid and benzoic acid and the salts, preferably alkali salts of these acids.

Neutral to weakly acidic aqueous 0.1 to 10% solutions of the water-soluble solutions are preferably used Peroxides.

In the preferred pH range from 2 to 7, especially 4 to 5, a certain pH can be used adjust with the help of buffer substances such as acetate or phosphate buffer systems.

In all cases at least as much peroxide should be used as the amount of phosphine to be oxidized is equivalent to. Stoichiometric excesses of the peroxide, on the other hand, do no harm and are intended to accelerate the process the reaction usually up to about 2 to 3 times the molar amount of the olefinic Connection even desired.

Since the success of the process according to the invention is ^{largely independent of temperature in the range from 0 to 30 °} C., it is preferred for practical reasons to carry it out at room temperature. In order to accelerate or also to moderate the conversion, however, sometimes higher or lower temperatures are recommended. This depends, among other things, on the amount of phosphine to be oxidized and also on the thermal sensitivity of the olefin. The optimal reaction conditions can easily be determined by simple preliminary tests.

A particular embodiment of the process according to the invention consists in the use of insoluble Redox resins with peroxide groups.

Such resins are obtained e.g. B. by chlorination of the sulfo or carboxyl groups of acidic ion exchange resins and then reacting these resins with sodium peroxide. If the solution of the olefinic compound is the resin, the Usually swollen with water, only insufficiently wetted, it is advisable to remove the resin before using it to be freed from water in a known manner and with a suitable organic solvent to re-flow. However, it is often sufficient to add a water-soluble solvent, e.g. B. of methanol or isopropanol, to the solution of the olefinic compound, in order to increase the wettability improve.

The peroxides can be allowed to act batchwise or preferably continuously on the organic solutions containing the substance mixture of phosphine and olefinic compound, if desired under an inert gas atmosphere, by any of the methods known per se and in any apparatus suitable for this purpose. On an industrial scale, the continuous procedure is preferred, e.g. B. the action of an aqueous peroxide solution on the organic solution of the mixture of phosphine and olefinic Ver _; bond in a countercurrent process or the oxidation 'of the phosphine to phosphine oxide into the peroxidic resin columns.

As a rule, prepurified mixtures of phosphine and olefinic compounds are used off, d. H. those which contain predominant amounts of the latter. The rest is then split up the phosphine, the phosphine oxide that is usually also already present and possibly for other impurities, which either do not interfere or are otherwise removed.

The phosphine oxides obtained in the present process can be prepared by conventional methods or, especially if this is difficult, can be separated by removing the Solution of the phosphine oxide-containing olefinic compound of the general formula III in a water-insoluble, lipophilic, non-polar or slightly polar organic solvent with a water-soluble one lipophobic, polar solvent extra -, - hiert.

Suitable water-insoluble organic solvents have already been mentioned above, while as a water-soluble solvent e.g. B. methanol, ethanol, isopropanol, acetone, acetonitrile, dimethylformamide and dimethyl sulfoxide, as well as mixtures of these solvents and especially mixtures with up to 80 percent by volume of water can be used.

Suitable solvent pairs include (mixing ratio in parts by volume):

Hexane, heptane, octane, nonane

and / or decane

Isooctane

Light petrol

Cyclohexane

Paraffin oil

Methylcyclohexane

Cyclooctane

Ligroin

toluene

Methanol-water in the proportions 95: 5 to
30:70, preferably 80:20 to 40:60
Ethanol-water (60:40)
Methanol-water (85:15)
Acetone — water (80:20 to 40:60)
Dimethylformamide — water (80:20 to 20:80)

Methanol-water (50:50)

A 0.1 to 30% solution of the phosphine oxide-containing olefinic compound is expediently extracted with 0.1 to 20 times the amount of the extractant. In general, it is advisable to carry out the extraction at room temperature, but temperatures sometimes prove in sensitive olefinic compounds up to -2O ⁰ C as appropriate. To achieve a faster equilibration, it is also possible at higher temperatures, up to about +60 ⁰ C to work.

For the extraction itself you can use all methods and apparatuses available in the art operate, i.e. it can be operated discontinuously by shaking it out, semi-continuously by means of the Carry out Craig distribution or, preferably, fully continuously in a countercurrent process, if desired in each case under an inert gas atmosphere.

The degree of purity of the olefinic compound can be determined both with regard to the tertiary phosphines as well as the resulting tertiary phosphine oxides can be determined chromatographically or spectroscopically. The good success of the method according to the invention can be described as surprising, since not to it was to be expected that the double bonds of the olefinic compounds, some of which were very sensitive, would through the peroxides are not attacked to any noticeable extent.

example 1

A solution of 800 g of octane and 100 g of crude vitamin A acid ethyl ester, the 1.5% phosphorus, as contained mainly triphenylphosphine, was charged with 1 1 of a 10 ° / _o aqueous Kaliumhydrogencaroatlösung (KHSO _5), the pH of the -Value 4, V was shaken at 20 ° C. for _{2 hours.}

The organic phase was then mixed 5 times at 20 ° C. with 1 liter each of a methanol-water mixture the volume ratio of methanol: water 9: 1 shaken out and then freed from the solvent.

The phosphorus content of the purified vitamin A acid ethyl ester phase fell below 0.001%.

Example 2

A solution of 800 g of cyclohexane and 100 g of crude vitamin A acetate, which is still about 1% of phosphorus, primarily as triphenylphosphine, containing V was added ₂ hour at 20 ⁰ C with 1 1 of aqueous 3% hydrogen peroxide solution having a with acetic acid pH was adjusted to 4.5, stirred vigorously.

The organic phase was then treated 5 times at 20 ° C. with a mixture of 600 ml of ethanol and 400 ml of water extracted. The vitamin A acetate phase remaining after the cyclohexane has been separated off contained less than 0.001% phosphorus.

extracted. The phosphorus content of the vitamin A palmitate phase As a result, it fell below 0.001%.

Example 4
5

A solution of 180 g of octane and 30 g of raw vitamin A acetate, which still contains 1.3% phosphorus, predominantly as triphenylphosphine

1 hour at 20 ⁰ C with 600 g of a peroxidic ίο Redoxharzes stirred vigorously, after which the separated octane solution and the resin was washed 3 times more with 100 g of octane.

The combined Octanlösungen were twice with 500 ml of a mixture of 450 ml methanol and 50 ml of water extracted, after which the phosphorus content of the vitamin A acetate phase was at 2O ⁰ C 5 less than 0.001%.

The redox resin was produced as follows: 1000 g of an acidic ion exchanger containing carboxyl groups were freed from adhering water by washing with ethanol and then with benzene and in benzene suspension chlorinated with 1000 g of thionyl chloride. The chlorinated resin was then in the course reacted for about 20 hours at 0 ° C with a solution of 400 g of sodium peroxide and 3080 g of water, separated from the water, suspended at 0 ° C in 4 1 10% sulfuric acid and "after the exchange ■ the Sodium cations were washed with water by protons until the water running off was neutral.

After that, the water was first displaced by ethanol and this by octane for the most part.

B e i s ρ i e 1 5

A solution of 800 g cyclohexane and 100 g camphene, which contains 1% phosphorus, mainly as triphenylphosphine, contains, with 1 1 of a 3% hydrogen peroxide solution, which has a pH value of 4.5,

Stirred at 25 ° C. for 2 hours. The organic phase is separated from the precipitated triphenylphosphine oxide freed by filtration, three times with 1 1 each of a methanol-water mixture of the volume ratio 3: 2 extracted and evaporated. The camphene recovered in this way contains less than 0.01% phosphorus.

Example 6

A solution of 800 g of cyclohexane and 100 g of cinnamaldehyde, which contains 1% phosphorus, mainly as triphenylphosphine, contains, is with 1 1 of a 3% hydrogen peroxide solution pH 4.5 for 2 hours stirred at 60 ° C. After cooling, the organic phase is washed 5 times with 1 liter each of a methanol-water mixture the volume ratio 1: 1 extracted and evaporated. The remaining cinnamaldehyde contains less than 0.01% phosphorus.

Example 3

A solution of 1800 g of light petrol (boiling range 80 to 100 ⁰ C) and 200 g of crude vitamin A palmitate, which still contained 0.8% phosphorus, mainly as triphenylphosphine, was at 20 ° C in an extraction apparatus that was about five theoretical Separation stages had been washed continuously in countercurrent with 21 2% strength aqueous Caro's acid.

Then the light gasoline phase was in the same apparatus with a mixture of 1800 ml Methanol and 200 ml of water at 20 ° C continuously

Example 7

A solution of 800 g of heptane and 100 g of oleic acid, 1% phosphorus, primarily as containing triphenylphosphine, is stirred with 1 1 of a 3% hydrogen peroxide solution whose pH is adjusted to 4.0 for 2 hours at 6O ⁰ C . The cooled organic phase is extracted 5 times with 1 l each time of a methanol-water mixture with a volume ratio of 3: 2 and freed from solvent. The oleic acid purified in this way contains less than 0.01% phosphorus.

Example 8

A solution of 800 g of cyclohexane and 100 g of oleic acid nitrile, which contains 1% phosphorus, predominantly as triphenylphosphine, is described as in Example 6 treated. The purified oleic acid nitrile contains less than 0.01% phosphorus.

Example 9

A solution of 800 g of heptane and 100 g of eugenol, which contains 1% phosphorus, mainly as triphenylphosphine, is treated as described in Example 6. The phosphorus content of the eugenol falls below this

^{0 '01} ° ^{/ o} Example 10

A 3-hydroxy-3,7-dimethyl-7-methoxyocten- (l) purified by fractional distillation contains 0.9% phosphorus, mainly as tributylphosphine. 80 g of the distillate are dissolved in 600 g of heptane and stirred with 800 ml of a 3% hydrogen peroxide solution at 60 ° C. for 2 hours. After cooling down the organic phase is separated off, concentrated and distilled. The distilled 3-hydroxy-3,7-dimethyl-7-methoxyocten- (l) then contains less than 0.01% phosphorus.

11th

10

25th

example

A solution of 70 g of methylene chloride and 1 g of vitamin Α acid containing 1.5% phosphorus, predominantly as triphenylphosphine, is mixed with 10 ml of 3% hydrogen peroxide, pH 4.5, for 2 hours at 35 ° C stirred under nitrogen. The organic phase is separated off and concentrated, and the vitamin which has crystallized out Α-acid filtered off. The acid recrystallized from methanol contains less than 0.01% phosphorus.

Claims (3)

Patent claims: 1. Process for the separation of small amounts of tertiary phosphines of the general formula 40 in which R ₁ , R ₂ and R _{3 are} aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radicals having 1 to 8 carbon atoms, preferably the phenyl group, of olefinic compounds of the general formula Rt C = C in which R ₄ , R ₅ , R ₆ and R _{7 are} hydrogen or saturated or unsaturated aliphatic, cycloaliphatic, araliphatic or aromatic radicals, the total number of carbon atoms should be at least 8 and where R ₄ . and R ₅ as well as R ₆ and R _{7 can} each be connected to form a 5- to 8-membered ring, characterized in that water-insoluble organic solutions of the mixtures of the tertiary phosphines of the above general formula and the olefinic compound are treated with aqueous solutions of peroxides and the resulting tertiary phosphine oxides of the general formula P = O in which R ₁ , R ₂ and R ₃ are as defined above, either in a conventional manner or by extraction of the solution of the phosphine oxide in a non-polar or slightly polar, water-insoluble, lipophilic organic solvent with a water-soluble, lipophobic, polar solvent. 2. The method according to claim 1, characterized in that the peroxide is neutral or weakly acidic solutions of water-soluble peroxides or a redox resin used, which peroxide Groups carries. 3. Process according to Claims 1 and 2, characterized in that it is carried out continuously executes. 009 521/236