DE1211139B - Process for the extraction of halohydrins - Google Patents

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FEDERAL REPUBLIC OF GERMANY GERMAN W) TW> PATENT OFFICE

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Int. CL:

C07c

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German class: 12 ο - 5/04

1211139
P29051IVb / 12o
March 24, 1962
February 24, 1966

The invention relates to a process for the extraction of halohydrins from aqueous solutions with aliphatic carboxylic acids having 4 to 20 carbon atoms.

Halohydrins are produced by chlorinating olefins and haloolefins in an aqueous medium produced and are expediently as dilute aqueous solutions, e.g. B. 2- to 10 weight percent Solutions. In general, better yields can be achieved if the solutions of the halohydrins are even more diluted. For example, one can hypochlorinate allyl chloride Obtain glycerol dichlorohydrin in technically satisfactory yields if you use it as an aqueous 2 to 4% dichlorohydrin solution (based on the weight of the solution). The best yields this halohydrins are obtained if the content is below 2 to 3 percent by weight of the aqueous Solution lasts.

The recovery of dichlorohydrin from such dilute solutions presents technical difficulties. You can z. B. fractionate the mixture, but this is too expensive. Solvents that are effective to be able to use to obtain the dichlorohydrin from the aqueous medium, turns out to be difficult for a number of reasons. In particular, some solvents react with the chlorohydrin and form impurities in the aqueous or organic phase. Others are after the implementation difficult to separate from the chlorohydrin during extraction. Still others are not stable enough and many have poor partition coefficients. Many solvents have been found to work with either have an undesirably high solubility in water or require large amounts in order to be effective To achieve extraction of the halohydrin from the water.

There has now been a process for the extraction of halohydrins which contain at least 3 carbon atoms contained, found from aqueous solutions with organic solvents, which thereby is characterized in that water-insoluble carboxylic acids having 4 to 20 carbon atoms or their Anhydrides used as solvents.

Above all, the glycerol dichlorohydrin isomers can in this way (1,3- and 2,3-glycerol dichlorohydrin) extracted from dilute aqueous solutions that contain small amounts of HCl (up to 2.5 percent by weight, based on the solution). This Extraction process can be carried out batchwise or continuously.

Examples of carbon processes which can be used according to the invention for the extraction of halohydrins

Applicant:

Pittsburgh Plate Glass Company,

Pittsburgh, Pa. (V. St. A.)

Representative:

Dr. W, Beil, A. Hoeppener and Dr. H. J. Wolff,

Lawyers,

Frankfurt / M.-Höchst, Adelonstr. 58

Named as inventor:

Malcolm Korach, Corpus Christi, Tex .;

James Leverette Guthrie, Laurel, Md. (V. St. A.)

Claimed priority:

V. St. v. America March 28, 1961 (98 771) -

acids are heptanoic acid, caprylic acid, pelargonic acid, capric acid, decanoic acid, chlorobutyric acid, dichloro butter acid, lauric acid, stearic acid, oxystearic acid, oleic acid, perfluorooctanoic acid, linoleic acid, Linolenic acid, eleostearic acid, licanic acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid or ricinoleic acid. Fatty acid mixtures from hydrolyzed glycerides can also be used, z. B. the hydrolyzed vegetable and sea fish oils, e.g. B. castor oil, coconut oil, corn oil, Cottonseed oil, linseed oil, oiticica oil, perilla oil, poppy seed oil, rapeseed oil, saffron oil, soybean oil, Sunflower oil, tallow oil, tung oil, cod liver oil or herring oil.

These aliphatic C ^ C ^ monocarboxylic acids have molecular weights above 116. The term "acids" also includes the anhydrides of the acids listed, mixtures of the anhydrides and monocarboxylic acids, substituted aliphatic monocarboxylic acids, substituted aliphatic monocarboxylic acids, such as alcoholic aliphatic hydroxymonocarboxylic acids -halogen-substituted aliphatic monocarboxylic acids (e.g. a, j8-dibromobutyric acid or perfluorooctanoic acid), alkyl-substituted aliphatic acids (e.g. a-ethyl-oc-methyl-butyric acid or 2-ethylhexanoic acid) etc. and their corresponding anhydrides. The acids mentioned are essentially insoluble in water; according to the ^{invention, their solubility in water at 20 °} C. should not exceed 2 percent by weight, based on water.

609 509/362

3 4

Extraction is carried out using the usual distillation temperatures. Extraction methods are used because of the risk of decomposition. So you can suspend the solution, so the technical rule was to use the dilute aqueous halohydrin solution extractants that set lower than dichloro and shake the solution to boil an intimate hydrine, so that a safe distillation contact between the halohydrin solution with the 5 was possible. Here, however, the difficulty arose in achieving the added solvent. After some that dichlorohydrin could not be obtained in the desired purity, two immiscible ones could be obtained. After the phases of the invention, one of which is predominantly from the process according to the present invention, it is possible to achieve the highest purity containing halohydrin, essentially with water, of the extraction material. Furthermore, immiscible solvents are to be borrowed and the other io note that, for economic reasons, it consists extremely mainly of water. It is important for the two phases that the extractants can be lost as much as possible and can be separated in the usual way. If the solution is loose and in a reusable and pure form is a C ₁₈ fatty acid, the aqueous can be recovered. The economical solutions of the fatty acid are added. The absence of the production of dichlorohydrins withstanding the halogenohydrin-containing fatty acid layer, there is no loss of extraction agents, as is then separated from the lower water use of volatile or low-boiling layers with the use of conventional means. You can also use the extraction solvents. In contrast, they can effectively operate in countercurrent. Here, the extraction agent used according to the invention is easily z. B. the solution with the higher specific weight lossless and without decomposition in the distillation at the top of a tower, z. B. a 20 can be recovered. The products have good Scheibel towers according to this in »Industrial and distribution coefficient. Another advantage is in Engineering Chemistry ", Vol. 42, p. 1048, June 1950, their high boiling point, which is ^{initiated at over 200 0} C and the process described and the other is thus above the boiling point of dichlorohydrin, solution from the lower end of the Tower introduced. which makes the work, as explained, much easier.
For example, an aqueous glycerol-dichloro-25 Unless otherwise stated, the working hydrin solution added at the top of the tower is 25 ⁶ C.
and the fatty acid in the lower part of the tower
pumped in. The one containing the glycerol dichlorohydrin

Fatty acid is obtained from the top of the tower- Example 1

drawn and the aqueous raffinate from the bottom

drawn * This process can be carried out in the usual way 211 an aqueous glycerol dichlorohydrin solution,

be carried out continuously, which contained 810 g of glycerol dichlorohydrin, was in

In general, the choice of the seven servings according to the invention depends on each 3 1 subdivided. Every 3-1 portion

appropriate C ₄ -C ₂₀ fatty acids or their anhydrides were added to 750 g of sodium chloride. Each portion

Some degree from the boiling point of the extra-35 was made by mixing with 257 cm ^{3 of} oleic acid in one

here from halohydrins. Acids extracted with a separatory funnel and shaking for 1 minute,

points above 100 ^° C., ie higher boiling points than when left to stand, two phases separated, one

z. B. that of the isomers of glycerol dichlorohydrin upper oleic acid dichlorohydrin phase and a lower one

(1,3-dichloro-2-propanol and ^, S-dichloro-l-propanpl), aqueous phase. The different layers were

have separated as particularly suitable for the extraction 4 ° and the seven oleic acid dichlorohydrin

of these isomers proved. The separation of the glycerol layers united. These united excerpts were

dichlorhydrins from the fatty acid is therefore easily added after about 300 g of oleic acid, which was previously used for the

usual distillation processes possible. Appropriately dichlorohydrine extraction had been used and

the boiling point of the extraction solvent contained an undetermined amount of dichlorohydrin,

at least 20 ^D C higher or lower than that of 45 The combined extract would be under a pressure of

extracted halohydrin. Since in the extracted 1 mm of mercury in a 30.5 cm long Vigreux

Solution usually distilled impurities such as Trichlor column, taking into account the vessel temperature

propane are present, they are allowed to rise from the at 14O ⁰ C. The maximum head temperature

Glycerol dichlorohydrin effective by fractionating the column was 5O ⁰ C.

Separated distillation. The recovered oleic acid was 50 The recovered oleic acid was in seven The solvent can then be divided into portions for further extraction, and each has been divided with each of the be turned. The glycerol dichlorohydrin can be mixed with the aqueous layers separated above. Preparation of glycerine by known hydrolysis. Each mixture was separated for one minute be used. funnel shaken and then left to stand until

It is known that two layers were created for the extraction of chlorohydrins. The oleic acid

to use diethyl ether from aqueous solutions. Layers were combined and placed on top of the described

This solvent is distilled because of its low boiling point.

point and its only low solubility in water The same extraction destination process

(75 g / l) technically not for the present purpose was repeated twice and each time the useful. Oleic acid recovered in the extraction of aqueous solutions 60 with that of the previous from Dichlorohydrins now, however, have the problem of extracting obtained aqueous layers

therein, on the one hand, the dichlorohydrin mixed in the highest.

To maintain purity and, on the other hand, for the four times this extraction

The solvents used in the extraction process used as much as possible. The distillation process yielded 808 g of distillate

listlessly and without decomposition, i.e. pure, accumulated back, which contained a small aqueous layer, to win. Since dichlorohydrins are relatively high after removing the aqueous layer and Have boiling points, and there is a general view of incomplete drying over 100 g of anhydrous insists that the dichlorohydrins are not the high calcium sulfate, 760 g of distillate resulted in the following analysis:

product Weight percent Weight percent based on the
anhydrous base,
average calculation l ^ -Glycerol dichlorohydrin
2,3-glycerol dichlorohydrin
1,2,3-trichloropropane
Unknown . > 31.0 (31.0)
56.5 (58.5)
3.0 (3.4)
0.3 (0.2)
9.3 (7.0) 33.7
62.6
3.4
0.3 water

The percentages by weight given in brackets in this table were based on a Reanalysis of the dried distillate found it to turn pale green on standing for several days and had been decolorized by heating with 1 percent by weight activated charcoal for a few minutes.

Example 2

Four 400 cm ³ portions of an aqueous solution containing 3.7% glycerol dichlorohydrin and 1% HCl, based on the weight of the solution, were placed in separating funnels with 0, 20, 40 and 100 g of common salt, respectively. The solutions were shaken until all of the salt was dissolved, then 50 cm ³ samples were taken for analysis. Each funnel were added 100 cm ³ of distilled tallow oil and the funnel shaken for 1 minute. After standing overnight, two layers had formed, a water layer and a tallow oil dichlorohydrin layer. The layers were peeled off individually and put 100 cm ³ of each layer into a 100 cm ³ cylinder

so graduation poured and weighed to the Determine the density of each layer. The eight samples obtained were then analyzed using Volhard chloride analysis analyzed for ionic chloride and after hydrolysis with alcoholic alkali, z. B. sodium ethanolate, tested for total hydrolyzable chloride.

The distribution coefficients were calculated for each salt concentration using the following equation:

Percentage by weight of organic Cl in sebum oil (density of the sebum oil layer)

Partition coefficient =

Percentage by weight of organic Cl in the aqueous layer (density of the aqueous layer)

in which the weight percentage of the organic Cl is the difference between the total hydrolyzable Represents chloride and the ionic chloride percentages.

The following distribution coefficients were obtained:

Added Distribution Amount of salt coefficients 1 Above 1.3 2 20 g 1.4 3 40 g 2.0 4th 100 g 3.7

Viscosity, SSU, 99 ° C 54

Viscosity, Gardner-Holdt,

25 ° C D

Specific gravity 25/25 ^a C 0.9465

Weight, kg / 1 at 25 ⁰ C 0.94

Boiling point, ⁰ C 204

Flash point, ⁰ C 224

The distribution coefficients are listed in the following table:

Example 3

The above experiment was repeated, but instead of the sebum oil, the same amount of sebum oil fatty acids used.

An analysis of the sebum oil used is then given:

Color, Gardner 8

Acid number 190

Saponification number 193

Iodine number 164

Resin acids,% 32.0

Unsaponifiables,% 1.4

Fatty acid, total% 66.6

Fatty acids:

Linseed oleic acid, conjugated,% 9

Linseed oleic acid, not conjugated,% · ■ 37

Oleic Acid,% 51

Saturated acids,% 3

Moisture none

Ash,% 0.01

Added Distribution Amount of salt coefficients 1 Above 1.4 2 20 g 1.9 3 40 g 2.2 4th 100 g 3.8

An analysis of the sebum oil fatty acids used showed:

Color, Gardner 9

Titer, ⁰ C 3

Acid number 189

Saponification number 192

Iodine number 138

Resin acids,% 3.5

Unsaponifiables 4.0

Total fatty acid,% 92.5

Fatty acids:

Linoleic acid,% 46.0

Oleic acid,% 51.0

Saturated acid,% 3.0

100.0

Moisture none

: Ash,% .... 0.005

Viscosity, SSU, 38 ° C 93

Viscosity, Gardner-Holdt,

25 ° C A

Specific gravity, 25/25 ⁰ C 0.9005

Weight, kg / ^{1.25 0} C 0.8942

Boiling point, ⁰ C 193

Flash point, ⁰ C 213

Example 4

. The procedure of Example 2 was repeated, but instead of the sebum oil and salt amounts of 50 and 250 g per liter, the same amounts of oleic acid were used.

■ There were
keep:

rehearse Added
Amount of salt Distribution
coefficients 1
2 ■
3 Og / 1
50 g / l
250 g / l 1.3
2.0
4.8

Example 5

The procedure of Example 2 was repeated with salt amounts of 0, 50, 150 and 250 g / l. A 1% strength solution of 1,3-glycerol dichlorohydrin which contained 1% HCl, based on the weight of the solution, was used as the aqueous solution. She had been prepared by mixing 100 cm ³ of concentrated HCl and 40 g of an aqueous 93 ° / _o by weight!, S-Glycerindichlorhydrinlösung, based on the weight of the solution prepared in 31 water. This experiment served to demonstrate the effect of diluting or changing the dichlorohydrin isomer ratio. The same tallow oil fatty acids as in Example 3 were used as extractants.

This is followed by a list of the received Distribution coefficient:

rehearse Salt concentration Distribution
coefficients 1
2
3
4th Og / 1
50 g / l
150 g / l
250 g / l 1.1
1.3
2.0 '
4.4

carried out by 300 cm ^{3 of} the aqueous solution and 50 cm ^{3 of} linoleic acid. It was found that the distribution coefficient was 1.5 at a 0 g NaCl concentration and 1.7 at a 30 g / l NaCl concentration:

When the following acids were used in place of linoleic acid in the above procedure get the following distribution coefficients:

solvent

Pelargonic acid

Cyclohexanecarboxylic acid
Capric acid

Without addition of NaCl

3.3
5.3
5.5

30 g / l

added

NaCl

3.8
6.8
6.5

the following distribution coefficients

. These results show that the ability of the Tallow oil acids, the 1,3-dichlorohydrin isomer £ 1%) Extracting from a 1% HCl solution is little different from its ability to extract a 3% To extract isomer mixture from a similar solution, which mainly contained the 2,3-isomer 2. All percentages are percentages by weight, based on the entire product.

Example 6

The procedure of Example 5 was repeated, but in this case an ^{aqueous glycerol dichlorohydrin solution prepared by mixing 114 g of the same dichlorohydrin with 70 cm 3 of} HCl in 3 l of water and linoleic acid in place of the tallow oil fatty acids. The extractions were made using

Example?

The procedure of Example 6 was repeated with salt concentrations of 0 and 30 g per liter and the same aqueous solution as in Example 5 was used. Instead of 50 cm ^{3 of} solvents, the extraction was carried out ^{with 100 cm 3 of solvent.} That used. The solvent was ricinoleic acid. The distribution coefficient obtained at salt concentration 0 was 3.1 and at 30 g / l 4.0.

Example 8

A stream of an aqueous solution of 3% glycerol dichlorohydrin, 1% HCl, 0.3% trichloropropane (refer to based on the weight of the solution) and additional sodium chloride to achieve a salt concentration of 25 g / l, was continuously introduced into the upper part of a glass extraction column filled with fillers. The column had a height of 6 m, a diameter of 5 cm and contained perforated plates. The fillers were porcelain saddles. In the lower part of the column, oleic acid was continuously fed to achieve countercurrent contact introduced with the aqueous solution. The streams were introduced so that the volume ratio of the aqueous solution to oleic acid was 1.5. That withdrawn from the lower part of the column aqueous raffinate contained 1% HCl and average less than 0.06% glycerol dichlorohydrin based on the weight of the solution. A HCl content left not prove yourself.

The raffinate was withdrawn and the oleic acid-dichlorohydrin stream introduced into a steam distillation plant. At this point more than 98% were

so (based on the weight of the solution) glycerol dichlorohydrin extracted into oleic acid.

The stream was heated to 160 ° C and introduced near the top of a 30 plate column. The glass one The column had a height of 1.80 m and a diameter of 2.55 cm. Steam at 160 ° C was with a Rate of 5 moles per mole of glycerol dichlorohydrin introduced into the lower part of the Column introduced to bring about countercurrent contact with the oleic acid stream. The ones below Oleic acid leaving part of the column contained an average of 0.06 percent by weight dichlorohydrin. These Oleic acid was circulated to the extraction column, so that only very little glycerol dichlorohydrin got lost.

A two-phase distillate was drawn off from the upper part of the distillation column and poured into collected in a boiler. It consisted only of water, glycerol dichlorohydrin, and a few parts per million

9 10

Oleic acid. The lower phase of the two-phase distillate water is introduced into the circuit and a solution

consisted of 85 percent by weight glycerol dichlorohydrin, continuously withdrawn, with the chlorohydrin

it made up 63 percent by weight of the distillate. The concentration was kept at about 1.83 percent by weight

upper phase consisted of 15 percent by weight glycerol. The yield of chlorohydrin was about 95.8%

dichlorohydrin and made 37 percent by weight of the 5 of the theoretical yield, based on the AUyI-

Distillate. 99 percent by weight of the glycerol chloride. °

dichlorhydrins in the oleic acid extraction stream. A portion of this aqueous solution is as in

distilled off. 90.5 percent by weight of the total GIy example 1 extracted with soybeans and the chlorine '

cerine dichlorohydrins were essentially completely in the acid phase in the lower hydrin

organic distillate phase. io extracted.

The aqueous upper distillate phase was The above examples are based on an extraction further hydrolysis of the dichlorohydrin to glycerol from glycerol dichlorohydrin (the composition of the collected. Another possibility is that the isomer mixture essentially corresponds in all cases to be fed in the circuit of the extraction column borrowed the one described in the table of Example 1), and with the flow of the aqueous solution with such 15 but the solvents mentioned can be used in the same Combine speed that the dichlorohydrin manner in the extraction of other halogen content of the feed stream to 3.3 weight hydrins from aqueous solutions, preferably percent increases and consequently the dichlorohydrin-thin aqueous solutions are used, content in the oleic acid extraction stream to 5.0 weight- The halohydrin of the present invention should percent increases. zo be able to get at least an oil percent

The 85 ° / _o strength Dichlorhydrinphase was dried aqueous HalogenhydrinlÖsung, based on the overall

and gave pure glycerol dichlorohydrin. Another important aspect of the solution is to form.

The possibility is to use the glycerol dichlorohydrin The new process can therefore be used for extraction solution e.g. with sodium carbonate with hydrolysis of ethylene chlorohydrin, ethylene bromohydrin, ethylene ends Treat hydrins to glycerin. 25 iodohydrin, primary and secondary propylene chlorine

The process described is particularly suitable for hydrin, primary and secondary propylene bromine .Improving the yield of glycerol dichlorohydrin, primary and secondary propylene iodohydrin, hydrin and similar chlorohydrins. As is known 3-chlorobutanol-2, l-chloro-2-methylpropanol-2, these chlorohydrins can be converted into 2-chloro-2-methylpropanol-1, <x- and / or jS-glycerol from Olefins such as ethylene, propylene, butylene or monochlorohydrin, 1,3-diiodo-2-propanol and 3-iododessene Chlorine derivatives such as allyl chloride with chlorine 1,2-propanediol from aqueous solutions in each Konin an aqueous medium. As a result of being concentrated, however, preferably from diluted the recovery of the chlorohydrin or its aqueous solutions with less than 10 weight-speaking Epoxyds encountered difficulties percent, z. B. 0.05 to 8 weight percent halogen these products are normally used in concentrated form. The halohydrins can trations of 3 to 6 percent by weight or more of one, two or more halogen groups per molecule manufactured. The yields are rarely above 90% containing one, two or more hydroxyl groups the theoretical yield. per molecule and up to 4 carbon atoms.

With the method according to the invention it is possible to carry out the present invention

Chlorhydrins in concentrations below 2 to 3 Ge 40 offers the use of solvents with a

Manufacture weight percent and gain by boiling point of at least 20 ⁰ C above or below the

only the water boiling point of the halohydrins to be extracted present in the reaction

quantity controlled and the solution obtained with considerable advantages. Using a

Carboxylic acid of the type described extracted. On solvent with such a deviating

In this way it is possible to separate the dichlorohydrin at 45 boiling point by distillation

Quantities of 95% and more, based on the theory- facilitated.

table yield, manufacture and extract, Is the solvent at normal temperaturewhat an important technical advantage over working conditions z. B. 25 ⁰ C, such. B. Stearin represents another method. acid, so the extraction can take place at a temperature

The following example applies to this procedure: 50 carried out slightly above the melting point of the acid

will. In general, the solid acids or

Example 9 Melting esters below 100 ^° C., but can also

higher melting solvents are used,

An aqueous solution of glycerol dichlorohydrin when the extraction process is carried out under pressure was prepared by circulating a water 55. In the case of stearic acid, which has a flow rate of 6.8 l / min. Has a melting point of 70 to 71 ⁰ C, a temperature through a 63.5 cm long tower with a diameter of 70 to 75 ⁰ C is expedient. There is a possibility of 71 mm, at which water from the ability of an esterification is deducted when using a higher upper part of the tower and its temperatures, but it does not pose a problem. The lower part was introduced, whereby at the same time 60 above-mentioned carboxylic acids remain essentially water-insoluble in the case of liquefied allyl chloride in the lower part of the tower esterification and remain at a rate of 2 cm ³ / min. also introduced effective extraction solvents for and so much chlorine also in the lower halohydrins. A slight esterification between part of the tower was introduced so that about 2% chlorine- see the carboxylic acids of the invention and the excess, based on the allyl chloride, present 65 halohydrins, e.g. B. glycerol dichlorohydrin, is in the real world. The temperature of the tower was generally at 5O ⁰ C advantageous for the process. To held. After the concentration of the glycerin example, an ester of glycerin-1,3- or chlorohydrin had risen to about 1.83%, 2,3-dichlorohydrin and stearic acid were better than ex-

traction solvent for glycerol dichlorohydrin as stearic acid itself.

According to a preferred embodiment of the invention, water-soluble MetaUhalogenid ^ - salts like sodium chloride of the aqueous S to be extracted Halohydrin solution added. Examples 2, 3, 4, 5, 6 and 7 show the addition of NaCl to the aqueous solution Halohydrin solution for better distribution of the halohydrin in the extract. Generally one leads An increase in the salt concentration from 0 to 25 g / l in the aqueous phase leads to an increase in the halohydrin partition coefficient by about 10% · In general, an addition of 30 to 250 g of salt increases per liter the partition coefficient to a value that allows the method to be used for extraction on a larger basis improved considerably, but completely saturated solutions can also be used. 30 to 100 g / l give very satisfactory results. In addition, the presence of small amounts of salt increases the Density of the aqueous layer resulting from the contact of the solvent with the aqueous solution, so that the phase separation in solvents with a specific gravity of less than 1 still is made easier. The water-soluble salts which can be used according to the invention include, for. B. inorganic alkali metal and alkaline earth metal salts, e.g. B. Sodium Chloride, Potassium Chloride, Sodium Sulphate, Potassium sulfate, magnesium chloride, calcium chloride or magnesium sulfate.

The extraction solvent is used for treating the aqueous halohydrin solutions in the ratio (aqueous halohydrin solution to solvent on a volume basis) of 0.01: 1 to 10: 1, preferably 0.5: 1 to 5: 1. This ratio can be changed if the concentration of the halohydrin in the aqueous solution exceeds 8% by weight by far.

Claims (3)

Patent claims: 1. Process for the extraction of halogen hydrins which contain at least 3 carbon atoms, from aqueous solutions with organic solvents, characterized in that one water-insoluble carboxylic acids with 4 to 20 carbon atoms or their anhydrides as Solvent used. 2. The method according to claim 1, characterized in that 'that glycerol dichlorohydrin is extracted. 3. The method according to claim 1 and 2, characterized in that the aqueous solution continuously in countercurrent with a continuously fed, water-insoluble carboxylic acid, brings, continuously extracted the halohydrin in the solvent, continuously the solvent removed from contact with the aqueous solution and the halohydrin recovered from the solvent. Considered publications:
German Auslegeschrift No. 1051 266.1 035 634. 609 509/362 2.66 © Bundesdruckerei Berlin