US2333726A - Process of preparing ether acids - Google Patents

Description

Patented Nov. 9, 1943 PROCESS OF PREPARING ETHER ACIDS Heinz von Leibitz-Piwnicki, Halle-on-the-Saale,

and Friedrich Meidert, Frankfort-on-the- Main, Germany; vested in the Alien Property Custodian No Drawing, Application May 3, i939, Serial No.

271,520. In Germany June 4, 1938 I I Claims. (Cl. 260-535) The present invention relates to a process of preparing mixtures of compounds containing the anions of aliphatic mono-basic ether acids and of mono-basic aliphatic carboxylic acids.

The manufacture of ether acids has already been described in the literature. The known procration of driers containing mixed'metal carriers,

. there are preferably used for the said neutralizaess starts from alcohols containing mor than 1 four carbon atoms, which in most cases are used in excess. An alkali metal iscaused to act upon such alcohols, the solutions of the corresponding alcoholates being obtained with evolution of heat. The alcoholates are then condensed with halogenated carboxylic acids, such as monochloro-acetic acid, monochlor'o-propionic acid or monochlorobutyric acid,,o r with the alkali salts of such acids, the alkali salts of the corresponding ether acids being thus formed; by acidification with a mineral vacid, the free ether acids may be obtained.

This process has a considerable inconvenience: Working with alkali metals is connected with important dangers; not only as regards storing and handling of the metal, but also with respect to the supervision of the violent exothermic reaction wherein large amounts of hydrogen are evolved which may give rise to the production of violent explosions.

Attempts have, therefore, been-made to substitute alkali hydroxide for the alkali metal used in this process; they have, however, all been unsuccessful until now, as has also been pointed out in the patents relating to this subject.

Now, we have found that in the preparation of ether acids the alkali metal may be replaced byalkali hydroxide, bysubjecting' a'mixture of alkali hydroxide and higher aliphatic alcohols to slow distillation, if desired with the aid of a fractionating column, a mixture of water and alcohol thereby passing over; there remains a solution of alcoholates containing only a small amount of unaltered alkali hydroxide. If the process is pursued'for some time, these last remainders of alkali hydroxide may also be transformed into alcoholates; this is, however, in most cases not necessary in practice, since in the subsequent condensation with water-soluble compounds containing the anions of aliphatic mono-halogenated carboxylic acids, such as mono-chloro-acetic acid, or even with the alkali salts of such acids, the said compounds react so quickly with the alcoholate that any decomposition caused by the presence of small amounts of free alkali is excluded. When the condensation is complete, these residual amounts of alkali may be neutralized by means of organic or inorganic acids. In case the acids or alkali salts thus obtained are used for the prepa- 55 tion naphthenic acids or mixtures of carboxylic acids obtained by oxidation of the so-called isobutyl oil or the like. The yields, calculated upon the amount of halogenated carboxylic acids or the alkali salts thereof, 'are nearly quantitative.

It has been ascertained, and this is surprising, that in the above-defined process the formation of the alcoholates which first takes place is accompanied by a secondary reaction, this reaction being very favorable in so far as it gives rise to the formation of a mixture of acids or alkali salts thereof which, when caused to react with polyvalent metals, yield very useful driers: Part of the alkali hydroxide reacts with the-alcohols so as to form the alkali salts of the corresponding carboxylic acids. The scope of this reaction may be varied by suitably choosing the alkali concentration, the temperature and duration of-the reaction, and the degree of pressure. A'proportion of, for instance, 60 parts of ether acid to 40 parts of carboxylic acid, or also of 50 parts of ether acid .to 50 parts of carboxylic acid may easily be obtained.

As starting material for the preparation of mixtures of ether acids and carboxylic acids or of the corresponding alkali salts, there is preferably used the mixture of alcohols which is known as the so-called isobutyl oil; it is formed in the synthetic preparation of methanol by catalytic hydrogenation of carbon monoxide and in the fractional distillation passes over at a temperature betweenabout and 220.

The formation of the alcoholate with alkali hydroxide, which precedes condensation with, for instance, monochloro-acetic acid or alkali monochloro-acetate, may in the case of simple or mixed alcohols of course also be brought about, very quickly and easily, by boiling an alkali hydroxide with water-soluble or water-insoluble alcohols, bringing the water-containing vapors, outside the reaction liquid, into contact with a dehydrating agent and reconducting the anhydrous condensate into the reaction mixture.

The aqueous solutions of the alkali salts of the ether acid and the carboxylic acid obtained after the condensation are preferably diluted with condensation Water, subjected to boiling and then caused to deposit. The supernatant alcohol is separated and the alcohol, which is still dissolved in the solution of the alkali salt, is distilled with superheated steam. The solution free from alcohol of the mixed alkali salts is then either split up by means of a dilute mineral acid, the free acids obtained belng then purified by known methods and worked up so as to form driers, or the solution or the alkali salt is directly used for the preparation of driers, if desired after neutralization by means of naphthenic acid, isobutylic acid or the like.

The following examples serve to illustrate the invention, but they are not intended to limit it thereto:

1. 7.2 kg. of sodium hydroxide and 130 kg. of isoheptanol are heated to boiling in such a manner that a mixture of water and alcohol passes over, this being preferably favorized by the ap plication of a fractionating column. The reaction is continued, until water does not distil any longer. 17.5 kg. of sodium of chloro-acetate are then introduced at 135 C. into the solution of the alcoholate thus obtained. The reaction is exothermic. 'I'hewhole is kept at 155 C. for half an hour, then allowed to cool, 150 l. of water are added and the alcohol standing above the liquid is separated. The alcohol still dissolved in the aqueous soap is expelled by steam distillation. The excess of alkali is neutralized by means of nitric acid,,and the soap solution may be used for the manufacture of driers.

2. As indicated in Example -1, a solution of alcoholates is prepared from 7.2 kg. of sodium hydroxide and 130 kg. of a mixture of alcohols known under the name of isobutyl oil and boiling at 150 C.-175 C., the alcoholates being then condensed with 17.5 kg. of sodium chloro-ac'etate. 130 l. of water are added to the reaction mixture, the alcohol which has separated is removed and the portion of the alcohol dissolved in the soap is expelled by steam distillation. The excess of alkali is neutralized by means of an acid liable to act as a metal carrier, for instance a mixture of carboxylic acids obtained by oxidation of the so-called isobutyl oil and having the acid number 320 (mg. of potassium hydroxide) or with naphthenic acid having the acid number 270; the soap thus obtained may directly be used for the preparation of driers.

3. 400 kg. of a mixture of alcohols known as isobutyl oil and boiling at 140 C.-l90 C. are heated in a boiler provided with a fractionating column until all of the water which may prehaps be present in the alcohol has passed over. 22.8 kg. of sodium hydroxide, in the form of scales, are then slowly introduced, while stirring, into the hot anhydrous alcohol. The temperature of the still being gradually raised to about 165 C., the water which has been produced during the formation of the alcoholate for the main part passes over at a temperature comprised between 90 C. and 110 C. For distilling the residual amount of water together with some alcohol, the temperature is finally raised to about 150 C. A clear yellowish liquid is thus obtained. It is allowed to cool to about 135 C., 23 kg. of solid sodium chloro-acetate being then added in two portions or more, with an interval of about-a quarter of an hour. n addition of the first half, the increase of temperature amounts to about 5 C. to about 6 C.; on addition of the second half it amounts to about 2 C.

to about 3 C. The reaction product is kept at 150 C. for about one hour and then allowed to cool. After addition of about 500 kg. of condensation water, the whole is subjected to boiling for a short time, then caused to deposit and the lower aqueous soap solution, which still contains considerable amounts of dissolved alcohol, is withdrawn. The alcohol is distilled from the soap solution by means of superheated steam.

The soap solution is then acidified with dilute sulfuric acid of about 10 per cent. strength, and the mixture of ether acid and carboxylic acid thus set free is twice washed with water and distilled under reduced pressure. Under a pressure of 7 mm., the acid distils at C.- C. in the form of a feebly yellowish oil. I'he yield amounts to 55 kg, the mixture obtained consisting of 34 kg. of ether acid having the acid number 308 and 21 kg. of carboxylic acid (acid number 347). Calculated upon the amount of sodium chloroacetate, the yield of ether acid, therefore, amount to 98% of the theoretical.

4'. 22.8 kg. of sodium hydroxide, in the form of scales, and 400 kg. of anhydrous iso-octanol are kept at boiling, temperature in a boiler provided with a fractionating column, until no water can any longer be detected in the alcohol which distils. A mixture of sodium alcoholate and sodium iso-octanoate is thus obtained; 19 kg. of monochloroacetic acid, dissolved in 50 kg. of octanol, are introduced into this mixture at about 40 C. in three portions, while stirring, in intervals of a quarter of an hour. In the course of the. exothermic reaction, the temperature rises to about 130. C. When the introduction of the acid is terminated, the reaction is completed by heating the mixture, while stirring for two hours, at 130 C.- C. The whole is then allowed to cool, about 500 kg. of condensation water are added, the mixture is allowed to deposit and the lower aqueous soap solution is separated.

The alcohol dissolved therein is removed by Instead of mono-chloroacetic acid and the salts thereof, there may also be used for the condensation other monohalogenated acids, for

instance mono-chloropropionic acid, monobromo-propionic acid, mono-chloro-butyric acid and the like or the salts of such acids.

We claim:

1. A method of producing mixtures of com pounds containing the anions of monobasic aliphatic ether acids and of monobasic aliphatic carboxylic acids which consists in treating monohydric aliphatic alcohols containing more than four carbon atoms first with alkali metal hydroxides at temperatures sufllciently elevated to drive off the water as formed in the reaction and then with water-soluble compounds containing the anions of aliphatic monohalogenated carboxylic acids.

2. A method of producing mixtures of compounds containing the anions of monobasic aliphatic ether acids and of monobasic aliphatic carboxylic acids which consists in treating monohydric aliphatic alcohols containing more than four carbon atoms first with alkali metal hydroxides at temperatures sufliciently elevated to drive oil the water as formed in the reaction and then with water-soluble aliphatic monohalogenated carboxylic acids.

3. A method of producing mixtures of compounds containing the'anions oi. monobasic aliphatic ether acids and or monobasic aliphatic carboxylic acids which consists in treating mono hydric aliphatic alcohols obtained as lay-prodnets in the synthesis of methanol and having a boiling point between 140 C. and 220 C., first with alkali metal hydroxides at temperatures sumciently elevated to drive of! the water as formed in the reaction and then with water-soluble compounds containing the anions of monohalogenated aliphatic carboxylic acids.

4. A method of producing mixtures of com}- pounds containing the anions oi monobasic aliphatic ether acids and of monobasic aliphatic carboxylic acids which consists in treating monohydric aliphatic alcohols containing more than four carbon atoms first with alkali metal hydroxides at temperatures sumciently elevated to drive ofl the water as formed in the reaction and then with water-soluble compounds containing the anions of aliphatic monohalogenated carboxylic acids with 2-4 carbon atoms.

5. A method of producing mixtures of compounds containing the anions oi monobasic aliphatic ether acids and of monobasic aliphatic carboxylic acids which consists in treating monohydric aliphatic alcohols obtained as byproducts in the synthesis of methanol and having a boiling point between 140 C. and 220 C., first with alkali metal hydroxides at temperatures sufficiently elevated to drive off the water as formed in the reaction and then with watersoluble compounds containing the anions of allphatic monohalogenated carboxylic acids with 2-4 carbon atoms.

6. A method of producing mixtures of compounds containing the anions of monobasic aliphatic ether acids and of monobasic aliphatic carboxylic acids which consists in treating monohydric aliphatic alcohols obtained as by-prodnets in the synthesis of methanol and having a boiling point between 140 C. and 220 0., first with alkali metal hydroxides at temperatures sufliciently elevated to drive ofl. the water as formed in the reaction and then with water-soluble compounds containing the anions of aliphatic monohalosenated carboxylic acids with 2-4 carbon atoms.

7. A method of producing mixture of alkali metal salts of a monobasic aliphatic ether acid and a monobasic aliphatic carboxylic acid which consists in heating to boiling isoheptanol with an alkali metal hydroxide, until water no longer distils, introducing sodium monochloroacetate, at 135 0., into the alcoholate solution thus obtained, keeping the mixture, for halt-an-hour, at

a temperature oi! 155 0., adding water to the reaction mixture, then separating the supernatant alcohol, from the aqueous soap solution expelling any alcohol still contained in this solution and neutralizing the alkali metal hydroxide.

8. A method of producing mixtures of alkali metal salts of monobasic aliphatic ether acids and monobasic aliphatic carboxylic acids which consists in heating to boiling a mixture of alcohols obtained as a byproduct in the synthesis of methanol and boiling at 150 C.-175 C. with an alkali metal hydroxide until water no longer distils, adding sodium mono-chloracetate at C. to the solution of alcoholates thus obtained, allowing the whole to cool, separating the alcohol and neutralizing the excess of alkali metal hydroxide by means of an acid liable to act as a metal carrier. l

9. A method of producing mixtures of monobasic aliphatic ether acids and monobasic aliphatic carboxylic acids which consists in heating to boiling a mixture of isobutyl alcohols until water no longer distils, gradually introducing an alkali metal hydroxide in the form of scales, while stirring, raising the temperature to about (3., allowing the liquid to cool to about 135 (3., adding solid sodium monochloro-acetate in several portions, while slightly raising the temperature, heating the reaction mixture, for one hour, at 150 (2., allowing it to cool, adding water, separating the alcohol, acidifying the mixture by means of dilute sulfuric acid, washing with water the mixture of ether acid and carboxylic acid thusset free and distilling it under reduced pressure.

10. A method of producing mixtures of alkali metal salts of a monobasic aliphatic ether acid and a monobasic aliphatic carboxylic acid which consists in heating to boiling anhydrous iso-octanol with an alkali metal hydroxide, until water'no longer distils, adding monochloro-acetic acid, dissolved in octanol, in three portions at about 40 C. while stirring, heating the mixture for several hours at 130 C.-150 (3., allowing it to cool, adding water, separating the alcohol and neutralizing the excess of alkali metal hydroxide by means of a mixture of carboxylic acids obtained by oxidation of the alcohol mixture formed as a by-product in the synthesis of methanol.

HEINZ V. LEIBI'IZ-PIWNICKI. FRIEDRICH MEIDERT.