EP0000140A1 - Process for the preparation of aqueous solutions or finely divided aqueous dispersions from polyenyltriarylphosphonium salts - Google Patents

Abstract

Process for the preparation of aqueous solutions of polyenyltriarylphosphonium salts from solutions of the corresponding polyenyltriarylphosphonium salts in organic solvents by driving off the solvent with water vapor, with some of the water vapor being allowed to condense. Some of the triarylphosphonium salts mentioned are directly suitable as pesticides, others serve as intermediates for organic syntheses, in particular in the carotenoid field.

Description

in der R für einen aliphatischen, cycloaliphatisch-aliphatischen oder aromatisch-aliphatischen Polyenylrest mit 5 bis 20 C-Atomen steht, X das Anionäquivalent einer starken Säure bezeichnet und Ar einen Arylrest, insbesondere den Phenylrest bedeutet.The present invention relates to a process for the preparation of aqueous solutions or aqueous finely divided dispersions of polyenyltriarylphosphonium salts of the general formula I.

in which R represents an aliphatic, cycloaliphatic-aliphatic or aromatic-aliphatic polyenyl radical having 5 to 20 carbon atoms, X denotes the anion equivalent of a strong acid and Ar denotes an aryl radical, in particular the phenyl radical.

Some of the compounds I (for example I with R. = ß-Jonylidenäthyl) are directly suitable as pesticides, for example for controlling water snails, others serve as intermediates for organic syntheses, in particular in the carotenoid field (see, inter alia, DT-PS 1 203 264 and 1 046 046). Both for immediate use and for use in further syntheses, such as for the preparation of synmetric carotenoids according to the DT-OS 2 505 869, aqueous solutions or aqueous, finely divided dispersions of the compounds I are frequently recommended.

Als Lösungsmittel für diese Umsetzung sind niedere aliphatische Alkohole, niedere Carbonsäuren, wie HCOOH oder CH₃COOH, Aceton, oder die üblichen wasserunlöslichen Lösungsmittel wie Benzol, Toluol, Tetrahydrofuran, Acetonitril, Methylenchlorid, Chloroform, Diäthyläther, Dioxan und Ester, wie Methyl- und Diäthylacetat bekannt, d.h. es fallen bei den üblichen Herstellungsmethoden Lösungen von I in den genannten Lösungsmitteln an. Eine direkte Umsetzung von Triphenylphosphin mit einer Säure und einem Polyenalkohol in Wasser zwecks Herstellung einer wäßrigen Lösung von Polyenyltriphenylphosphoniumsalzen (I) erscheint aussichtslos, da einerseits weder das Triphenylphosphin noch der Polyenalkohol in Wasser löslich sind, andererseits mit einer großen Hydrolyseempfindlichkeit von I bei höheren Temperaturen zu rechnen ist und man annehmen kann, daß das Vorhandensein größerer Mengen eines der bei der gewünschten Reaktion sich'bildenden Produkte, das Reaktionsgleichgewicht ungünstig beeinflußt.According to Houben-Weyl, "Methods of Organic Chemistry", Volume XII / 1, pages 90 ff. Phosphonium salts from triphenylphosphine, an acid and an alcohol according to the reaction equation

Lower aliphatic alcohols, lower carboxylic acids, such as HCOOH or CH ₃ COOH, acetone, or the customary water-insoluble solvents, such as benzene, toluene, tetrahydrofuran, acetonitrile, methylene chloride, chloroform, diethyl ether, dioxane and esters, such as methyl and Diethyl acetate is known, ie solutions of I in the solvents mentioned are obtained in the customary production methods. A direct reaction of triphenylphosphine with an acid and a polyene alcohol in water to produce an aqueous solution of polyenyltriphenylphosphonium salts (I) seems hopeless, since on the one hand neither the triphenylphosphine nor the polyene alcohol are soluble in water, on the other hand with a high sensitivity to hydrolysis of I at higher temperatures is to be expected and it can be assumed that the presence of large amounts of one of the products formed in the desired reaction adversely affects the reaction equilibrium.

According to the known method, the best yields of I are obtained when using lower alcohols, such as ethanol, isopropanol, isobutanol, n-propanol, n-butanol and especially methanol as the solvent. For example, solutions of I in the lower alcohols mentioned, in particular, are preferred as starting solutions for the preparation of aqueous I solutions special methanolic I solutions are used. The conversion of solutions of I in one of the other solvents mentioned above into aqueous I solutions is also of interest. The preparation of aqueous I solutions which are as solvent-free as possible from the corresponding solutions in organic solvents by completely removing the solvent by distillation and taking up I in water is inevitable due to the inevitable local overheating and the great thermal sensitivity of the compounds I (slc p. 105) Loss of yield connected and therefore hardly technically feasible. If the solutions of I in organic solvents are first mixed with water and then the solvent is distilled off, the solutions generally begin to foam so violently that regular distillation is no longer possible. The use of solvents in which I is less readily soluble, then allowing I to crystallize out of the solvent and taking up I in water does not appear to be very attractive, owing to the high expenditure of time and apparatus and the losses in yield which are unavoidable in crystallization processes. On the other hand, the reaction cannot be carried out without a solvent, since otherwise (especially when using sulfuric acid as a proton donor) decomposition of the alcohol or oxidation of the phosphine to the corresponding phosphine oxide occur.

It was therefore the object of the invention to prepare aqueous solutions or finely divided, aqueous dispersions of I in the simplest and most economical manner.

in der R für einen aliphatischen, cycloaliphatisch-aliphatischen oder aromatisch-aliphatischen Polyenylrest mit 5 bis 20 C-Atomen steht, X das Anionäquivalent einer starken Säure bezeichnet und Ar einen Arylrest, insbesondere den Phenylrest bedeutet, in einem organischen Lösungsmittel in 10- bis 70-gewichtsprozentige, weitgehend lösungsmittelfreie, wäßrige Lösungen bzw. feinteilige Dispersionen, gefunden, das dadurch gekennzeichnet ist, daß man das Lösungsmittel sowie sonstige von der Synthese von I herstammenden, wasserdampfflüchtigen Verbindungen aus der auf 30 bis 120°C gehaltenen Lösung mit Wasserdampf abtreibt, wobei man einen Teil des Wasserdampfes zur Erzeugung der wäßrigen Lösungen kondensieren läßt. Beim Abkühlen unter Rühren bilden sich aus diesen homogenen, viskosen I-Lösungen feinteilige Dispersionen.Surprisingly, it has now become a very advantageous process for converting about 10 to 70 percent by weight solutions of polyenyltriarylphosphonium salts of the general formula I

in which R represents an aliphatic, cycloaliphatic-aliphatic or aromatic-aliphatic polyenyl radical having 5 to 20 carbon atoms, X denotes the anion equivalent of a strong acid and Ar denotes an aryl radical, in particular the phenyl radical, in an organic solvent in 10- to 70 -Weight percent, largely solvent-free, aqueous solutions or finely divided dispersions, which is characterized in that the solvent and other compounds derived from the synthesis of I, volatile in steam from the solution kept at 30 to 120 ° C with steam, whereby some of the water vapor is allowed to condense to produce the aqueous solutions. When cooling with stirring, these homogeneous, viscous I solutions form finely divided dispersions.

It was also surprisingly found that this process can be carried out particularly well continuously by passing the organic solution from I continuously from above into a column, preferably into a packed column, and bringing it into contact with the steam in countercurrent; this allows a part of the water vapor to condense and continuously draws off the aqueous solution of I formed from the lower part of the column. The dosage of the I solution and of the water vapor can easily be set up in such a way that the desired aqueous I solution can be drawn off directly as a bottom product in the form of a homogeneous, viscous solution.

The hot bottom product is advantageously continuously transferred to a stirred tank. Cooling and stirring generally gives this hot, aqueous I solution a dispersion which contains finely divided, crystalline phosphonium salt, dispersed in water or in aqueous phosphonium salt solution.

It is known that the melting points or the decomposition points of the triarylphosphonium salts, in particular the triphenylphosphonium hydrogen sulfates, are above 100 ° C. (ß-Jonylidentriphenylphosphonium hydrogen sulfate melts, for example, at 183-85 ° C. with decomposition, axerophthyltriphenylphosphonium hydrogenation and the decomposition at 188–190 ° C. sulfate at 188-190 ° C. sulfate at 188-190 ° C. sulfate at 188–19 ° C. sulfate at 188-190 ° C. sulfate at 188–190 ° C. sulfate at 188–19 ° C. sulfate at 188–19 ° C. sulfate at 188–19 ° C. sulfate at 188–19 ° C. sulfate at 188–19 ° C.) and that at 188–19 ° C. sulfate at 188–19 ° C. and the decomposition points of the triarylphosphonium salts are known to be above 100.degree The solubility of the triarylphosphonium salts in water is low, especially at room temperature. It was therefore to be expected that with a continuous procedure in a column with decreasing concentration of the organic _. see solvent in the stripping section of the column partially crystallize out the phosphonium salts and clog the column. Surprisingly, such difficulties do not occur in the process according to the invention.

The process according to the invention can be carried out batchwise or continuously. Surprisingly, no disruptive foam formation can be observed either in a batch or in a continuous process variant.

To carry out the discontinuous variant, the solution of I in the organic solvent is kept in a reaction vessel at a temperature just below the boiling point of the solvent, water vapor is introduced into it and the solvent evaporating therefrom, other compounds derived from the synthesis of I, and volatile compounds and one Distill off part of the water vapor from the reaction vessel.

The following can generally be said about the operating conditions for the continuous variant according to the invention: The temperature of the input solution should be below the boiling point of the solvent; the bottom temperature should be about 100 ° C; the feed is to be regulated in such a way that the solvent largely evaporates on the packing by dissolving through the column. A small column height is sufficient for a small feed, and the column capacity must be correspondingly larger for larger throughputs. In detail, the suitable operating conditions can easily be determined on the basis of a few preliminary tests, so that detailed explanations are not necessary. This also applies to working at lower or higher pressure than normal pressure.

deren Methylhomologen oder den Axerophtylrest (III)

und dessen Methylhomologen. Allgemein kommen als Polyenylreste solche mit 5 bis 20 C-Atomen und mindestens 2 konjugierten Doppelbindungen in Betracht, wobei eine der konjugierten Doppelbindungen auch eine Kohlenstoff-Sauerstoffbindung sein kann, wie z.B. in dem Rest 0=C-C=C-C-. Diese Reste können auch weitere -C=C-Gruppierungen enthalten und u.a. Hydroxyl-, Methoxy- oder Acetoxygruppen als Substituenten tragen. Der cycloaliphatische Rest kann auch durch einen aromatischen Rest, wie Phenyl oder alkyliertes, insbesondere methyliertes Phenyl, ersetzt werden.The good success of the process according to the invention is practically not dependent on the nature of the polyene residues in the phosphonium salts I according to previous observations. Since Wittig's ylide synthesis is primarily used to prepare compounds of the carotenoid series, above all of vitamin A and its derivatives, and of .beta.-carotene itself, such polyenyl radicals are of the greatest importance as to what building blocks are for these carotenoids. Particularly mentioned are those phosphonium salts in which R represents the α - or ß-Jonyliden- äthylrest (IIa or IIb),

their methyl homologues or the axerophthal residue (III)

and its methyl homologue. In general, suitable polyenyl radicals are those having 5 to 20 carbon atoms and at least 2 conjugated double bonds, it being possible for one of the conjugated double bonds to also be a carbon-oxygen bond, for example in the radical 0 = CC = CC-. These radicals can also contain further —C = C groupings and, among other things, bear hydroxyl, methoxy or acetoxy groups as substituents. The cycloaliphatic radical can also be replaced by an aromatic radical, such as phenyl or alkylated, especially methylated phenyl.

The type of anion in the polyenyltriarylphosphonium salt is also irrelevant to the success of the process according to the invention. In general, the phosphonium salts of strong acids such as H ₂ S0 ₄ , HCl, HBr, HCOOH and H ₃ P0 ₄ are used, so that X in I for HSO ₄ ^⊖ , Cl ^- , Br ^- , HCOO⊖ or H ₂ PO ₄ ^⊖ , preferably stands for HSO ₄ ^⊖ .

In principle, the process according to the invention is suitable for converting I solutions into all organic solvents which, when water vapor is blown in, have a loading proportion of the water vapor with organic solvent of 10% and more and which have a boiling point of about 50 to 150 ° C. The process is of particular importance for those solvents in which the polyenyltriarylphosphonium salts can be prepared in particularly good yields and in which the phosphonium salts are readily soluble. Lower alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol and isobutanol, may be mentioned; lower carboxylic acids such as HCOOH and acetic acid as well as acetone and methylene chloride. The method according to the invention is used with particular advantage for checking methanolic solutions of polyenyltriarylphosphonium salts.

The solutions of I in organic solvents are prepared by customary methods from triarylphosphine, in particular triphenylphosphine, a strong acid such as HC1, HBr, HCOOH, H ₃ PO ₄ or in particular sulfuric acid and a compound RX, where X is preferably a free hydroxyl group or is a hydroxyl group esterified with a lower carboxylic acid such as acetic acid. Other methods of producing triarylphosphonium salts can of course also be used.

Small amounts of triphenylphosphine or the starting compound R-X, and of by-products which form in this quaternization reaction, are partially volatile with water vapor, so that the process according to the invention has the advantage of producing pure aqueous I solutions or pure finely divided aqueous dispersions. Since the preparation of solutions of I in organic solvents is not the subject of the invention, further details on this are unnecessary.

The amount and temperature of the required water vapor depend on the circumstances of the individual case. For example, if it is pure methanolic I solutions, about 1 - 3 kg of water vapor at 100 ° C are required to remove 1 kg of methanol. This value decreases with increasing temperature and becomes larger with falling temperature and under reduced pressure, so that concentrated aqueous I solutions are obtained when using higher steam temperatures. If the methanolic I solutions still contain impurities (usually about 1 to 10 mole percent of I), additional steam is required to drive them out. On the basis of this information, the person skilled in the art can determine the optimal process conditions, including the setting of the reflux ratio, by means of a few preliminary tests. By By suitable design of the column, for example, 80-90 percent methanol can be distilled off over the top of the column.

When checking solutions of polyenyltriarylphosphonium hydrogen sulfate in a solvent in which the phosphonium salt is poorly soluble, such as in isopropanol or acetone, it is advisable, if the solution of I is to be fed continuously into the reaction vessel, of the solution before the steam treatment add a little water to bring crystallized phosphonium salt into solution. In general, it can be said that the presence of certain amounts (up to about 50 percent by weight) of water in the organic I solution before and during the steaming treatment is not disadvantageous, in some cases even advantageous.

If the continuous mode of operation is used, packed columns with a suitable number of theoretical plates are expediently used as columns in order to remove the solvent quantitatively. Special features in terms of equipment or materials are to be taken into account only to the extent that the acidic aqueous phosphonium salt solutions have a corrosive effect on the material of the reaction vessels.

In all cases it is possible to remove the solvent completely, but it is generally sufficient to work towards a residual solvent content of 1 to 2 percent by weight. The resulting solvent-water mixtures can be laid in their components by distillation in the usual way and the solvent can be used again.

The aqueous I solutions or finely divided dispersions of I in water obtained as process products can be used for further reactions, e.g. used for the production of symmetrical carotenoids, such as the ß-carotene or for the production of vitamin A or by the usual methods, e.g. can be used as pesticides.

example 1 a) Preparation of a methanolic solution of β-Jonyliden-ethyltriphenylphosphonium hydrogen sulfate

To a mixture of 700 ml of methanol and 258 g of triphenylphosphine, 99 g of sulfuric acid and 220 g of vinyl-ß-ionol (93% purity) were added dropwise in succession while stirring and cooling to 25 ° -30 ° C. After 12 hours the mixture was extracted 3 times with 250 ml of heptane each time. 1150 g of an approximately 43% methanolic solution of β-jonylidene-ethyl-triphenylphosphonium hydrogen sulfate are obtained.

b) transfer of the methanolic into an aqueous solution of β-Jonyliden-ethyl-triphenylphosphonium hydrogen sulfate

The methanolic phosphonium salt solution obtained in accordance with FIG. 1a was added in 90 minutes from above to a packed column made of glass 50 cm long and 3 cm in diameter. The column was filled with glass Raschig rings and insulated. At the lower end of the column, 3 900 g of water vapor were blown in over the course of 90 minutes. The aqueous phosphonium salt solution or suspension was drained from the bottom of the column via a siphon and collected in a stirred flask. About 1,400 g of an easily stirrable, aqueous suspension were obtained which contained 497 g of β-jonylidene-ethyl-triphenylphosphonium hydrogen sulfate. This corresponds to a loss of 95% of theory.

Example 2 a) Preparation of a methanolic solution of axerophthyl triphenylphosphonium hydrogen sulfate

49 g of sulfuric acid and 154 g of vitamin A acetate were added in succession to a mixture of 400 ml of methanol and 131 g of triphenylphosphine in 30 minutes while stirring and cooling to 10 ° C. The reaction mixture was then stirred at 25 ° C. for a further 12 hours. 665 g of an approximately 38% strength methanolic solution of axerophthyl triphenylphosphonium hydrogen sulfate were obtained.

b) transfer of the methanolic into an aqueous phosphonium salt solution

The methanolic solution obtained according to 2a was added in 60 minutes from above to the packed column described in Example 1. At the lower end of the column, 2,200 g of water vapor were blown in over the 60 minutes. About 1,000 g of bottom effluent were obtained.

c) further processing of the aqueous phosphonium salt solution

The aqueous solution of axerophthyltriphenylphosphonium hydrogen sulfate obtained was converted to β-carotene according to Example 6 of DOS 25 05 869. After isomerization of the product obtained in heptane, alltrans-ß-carotene was obtained in 70% yield, based on the vitamin A acetate used.

Example 3

a) 700 ml of glacial acetic acid were mixed with stirring with 262 g of triphenylphosphine and 90 g of sulfuric acid. The reaction mixture was then added within 2 hours 220 g of vinyl-ß-ionol (purity 93%) were added dropwise with stirring and cooling. Care was taken to ensure that the temperature did not exceed 35 ° C. Finally, the reaction mixture was left to react for a further 12 hours with stirring.

b) The solution of β-Jonylidene-ethyl-triphenylphosphonium hydrogen sulfate in acetic acid obtained according to 3a was transferred to a flask provided with a distillation bridge and receiver and blown into this in about 2 hours at 30-40 mbar, 1.67 kg of water vapor, the temperature rose to 40 - 45 ° C. This gave 1.9 kg of distillate, which essentially contains acetic acid and water, and 1.1 kg of sump, which contains 501 g of β-Jonylidenäthyltriphenylphosphoniumhydrogensulfat as an aqueous solution or suspension. This corresponds to a yield of 96%, based on the vinyl-ß-ionol used.

Example 4

a) 700 ml of methanol were mixed with 258 g of triphenylphosphine and 100 g of crystalline phosphoric acid (dissolved in as little water as possible). 220 g of vinyl-β-ionol (degree of purity 93%, corresponding to 0.93 mol) were added dropwise to this mixture in the course of 2 hours with stirring. The mixture was then heated to boiling under reflux for an hour. After cooling, the mixture was extracted 3 times with 250 ml of heptane each time. 1 150 g of an approximately 34% methanolic solution of ß-Jonyliden-ethyl - triphenyl-phosphonium phosphate were obtained.

b) The methanolic solution obtained in accordance with FIG. 4a was treated with steam in the column described there as in Example 1. 1,400 g of a 26% suspension of β-jorlylidene-ethyl-triphenylphosphonium were obtained. phosphate in water. This corresponds to a yield of 70%, based on the vinyl-ß-ionol used.

Example 5

a) 854 g of formic acid were mixed with stirring with 262 g of triphenylphosphine. 220 g of vinyl-β-ionol (degree of purity 33%) were added dropwise to this mixture in the course of 2 hours. It was ensured that the temperature of the reaction mixture did not exceed 35 ° C. The reaction mixture was then left to react for a further 12 hours with stirring. 1,340 g of an approximately 27 percent by weight solution of β-Jonylidenäthyl-triphenylphosphonium formate were obtained.

b) In the solution obtained according to 5a was analogous to Example. 3b in the apparatus described therein, 1.7 kg of water vapor were blown in at 40 mbar in 6 hours. About 1.5 kg of distillate, which contains formic acid and water, and 1.5 kg of sump, which contains 0.65 mol of β-Jonylidenäthyl-triphenylphosphonium formate dissolved or suspended in water, were obtained. This corresponds to a yield of about 70% of theory, based on the vinyl-β-ionol used.

c) If the formic acid solution obtained in accordance with 5a is treated continuously with water vapor analogously to Example 1b, almost the same yields of aqueous β-Jonylidenäthyl-triphenylphosphonium formate are obtained as in 5b.

Example 6

a) 550 g of ethanol were mixed with 258.5 g of triphenylphosphine and 99.5 g of concentrated sulfuric acid and then to this mixture first within 15 minutes 220 g of vinyl-ß-Jonol (purity 95%) were added dropwise in 60 minutes. The reaction mixture was then left to react for 20 hours at room temperature. 1 128 g of an approximately 40% by weight ethanolic solution of β-jonylidene-ethyl-triphenylphosphonium hydrogen sulfate were obtained.

b) The solution obtained according to 6a was treated with steam in the same manner as in Example 1 in the column described there. 1,400 g of an aqueous suspension were obtained, which contained 454 g of β-Jonylidenäthyl-triphenylphosphoniumhydrogensulfat. This corresponds to a yield of 85%, based on the vinyl-ß-Jonol used.

Example 7

a) 700 ml of isopropanol were mixed with 258.8 g of triphenylphosphine and 99.5 g of concentrated sulfuric acid were added dropwise to this mixture in 15 minutes and then 220 g of vinyl-β-ionol (purity 93%) in 60 minutes. The β-Jonylidenäthyl-triphenylphosphonium hydrogen sulfate formed partially crystallized out and was brought into solution by adding 200 ml of water.

The solution obtained in accordance with FIG. 7a was treated with steam in the same manner as in Example 1 in the column described there. 1,450 g of an aqueous suspension (or emulsion) were obtained, which contained 470 g of β-jonylidene-ethyl-triphenylphosphonium hydrogen sulfate. This corresponds to a yield of 90%, based on the vinyl β-ionol used.

Example 8

a) 700 ml of isobutanol were mixed with 258.5 g of triphenylphosphine and 99.5 g of concentrated sulfuric acid and then 220 g of vinyl-β-ionol (purity 93%) were added dropwise to this mixture as in Example 6. The reaction mixture is then mixed with 200 ml of water and heated to 50 ° C. for 2 hours.

b) The solution obtained in accordance with FIG. 8a was treated with steam in the same manner as in Example 1 in the column described there. 1,500 g of an aqueous suspension (or emulsion) containing 480 g of β-jonylidene-ethyl-triphenylphosphonium hydrogen sulfate are obtained. This corresponds to a yield of 92%, based on the vinyl-ß-ionol used.

Example 9

a) 700 ml of acetone were mixed with 258.5 g of triphenylphosphine and 99.5 g of concentrated sulfuric acid and then 220 g of vinyl-ß-ionol were added dropwise to this mixture as in Example 6. The reaction mixture was then mixed with 100 ml of water, heated to 30 ° C. for 2 hours and left to react for a further 20 hours.

b) The solution obtained in accordance with FIG. 9a was treated with steam in the same manner as in Example 1 in the column described there. 1,450 g of an aqueous suspension (or emulsion) containing 470 g of β-Jonylidenäthyl-triphenylphosphonium hydrogen sulfate are obtained. This corresponds to a yield of 90%, based on the vinyl-β-ionol used.

Example 10

a) 700 ml of methanol were mixed with 50 ml of pyridine, 50 ml of concentrated aqueous HC1 and 6 ml of a 10 percent by weight solution of butylated hydroxyanisole in benzene, the mixture was stirred for 5 minutes and then according to DT-OS 25 37 072 with 139 g of triphenylphosphine and 120 g of vinyl-β-ionol (degree of purity 93%) are added. The reaction mixture was then extracted 4 times with 250 ml of heptane.

b) The methanolic solution obtained in accordance with 10a was treated with steam in the same manner as in Example 1 in the apparatus described there. 1,450 g of an aqueous suspension which contains 386 g of β-jonylidene-ethyl-triphenylphosphonium chloride are obtained. This corresponds to a yield of 83%, based on the vinyl-ß-ionol used.

Example 11

800 ml of methylene chloride were mixed with 262 g of triphenylphosphine. 99.5 g of concentrated sulfuric acid and then 220 g of vinyl-β-ionol were added dropwise to this solution at 10-15 ° C. while stirring and cooling. The mixture is left to react for 12 hours at room temperature. As in Example 1, this solution was continuously added to the column described there in 90 minutes.

At the same time, about 2 kg of water vapor were blown in. 800 ml of methylene chloride and about 1.3 kg of water were obtained as the distillate.

The methylene chloride can be used again after the water has been separated off and distilled.

The bottom was drained into a stirred flask and cooled to room temperature with continued stirring. 1,200 g of an easily stirrable aqueous crystal mash were obtained, which contained 497 g of β-ionylidene triphenylphosphonium hydrogen sulfate.

This corresponds to a yield of 93% of theory.

Claims (3)

1. Method for checking 10- to 70 percent by weight solutions of polyenyltriarylphosphonium salts of the general formula I

in which R represents an aliphatic, cycloaliphatic-aliphatic or aromatic-aliphatic polyenyl radical having 5 to 20 carbon atoms, X denotes the anion equivalent of a strong acid and Ar denotes an aryl radical. means, in an organic solvent in largely solvent-free aqueous solutions or finely divided dispersions, characterized in that the solvent and other compounds derived from the synthesis of I, which are volatile in steam, are driven off from the solution kept at 30 to 120 ° C with water vapor, with one Part of the water vapor can be condensed to produce the aqueous solutions or the finely divided dispersions. 2. The method according to claim 1, characterized in that the organic solution of I is continuously passed from above into a 'column, continuously brought into contact with the water vapor in countercurrent, thereby allowing part of the water vapor to condense and the aqueous solution of I formed withdraws continuously from the lower part of the column. 3. The method according to the 'claims 1 and 2, characterized in that one starts from methanolic I solutions.