DE854524C - Process for the production of chloraryloxy fatty acids - Google Patents

Description

Process for the preparation of chloraryloxy fatty acids The invention relates to a process for the production of chloraryloxy fatty acids or their salts.

It is known that chloraryloxyacetic acids can be obtained by heating a mixture from an alkali salt of the corresponding phenol with sodium chloroacetate and Water can be represented. So can the sodium methylchlorophenoxyacetate from the corresponding chlorocresol, sodium chloroacetic acid, water and caustic soda be represented by heating under return flight. The sodium chlorophenoxyacetate can e.g. B. by reacting the corresponding chlorophenol with monochloroacetic acid obtained in the presence of caustic potash and water. However, the reaction proceeds not completely, and a substantial proportion of the chlorocresol or chlorophenol will not be implemented. It has now been found that when preparing chloraryloxy fatty acids or their salts by reacting the corresponding nuclear chlorinated phenol with a substantial excess of an α-halo fatty acid in the presence of excess Alkali, d. H. Alkali hydroxide, alkali carbonate or alkaline earth hydroxide, an improved Yield can be achieved if the acid shares with the excess alkali is added in parts during the reaction.

According to the present invention are therefore for the production of Chloraryloxy fatty acids or their salts, phenols with a substantial amount of nuclear chlorinated phenols Excess of α-halogen fatty acid reacted in the presence of excess alkali and the acid together with excess alkali during the reaction in parts added. It is in this case it is advantageous to first use stoichiometric amounts of the chlorinated phenol and the halogenated fatty acid in the presence of a small excess of alkali to implement and then a further amount of the halogenated fatty acid in the amount of at least a quarter of the amount previously used together with a small excess of alkali to add. The reaction is expediently carried out by heating the reactants under Induced reflux.

The term nuclear chlorinated phenols means chlorinated phenols or naphthols with only one or more hydroxyl groups and with or without alkyl substituents, like methyl, ethyl, propyl7 or isopropyl radicals to be understood.

In one embodiment of the invention, a chlorocresol, e.g. B. a monochlorocresol, with an equimolar amount of an α-chloro fatty acid, e.g. B. monochloroacetic acid, and excess caustic soda solution mixed together. A caustic soda solution is useful with IS up to 25% caustic soda in an amount that corresponds to an io to 200 / own excess, used. The mixture is then for some time, e.g. B. i to 2 hours, under reflux heated. Then more monochloroacetic acid, in an appropriate amount about 2o to 30% of the amount originally used, plus additional caustic soda in added a small excess over the additional amount of acid. It can also be a equivalent amount of sodium chloroacetate, along with a small amount Caustic soda can be added. The mixture is then again for some time, e.g. B. i to 2 hours, heated under reflux. The reaction product can then be isolated will. The method of isolation depends on factors such as the solubility of the product in the reaction mixture. In many cases the sodium salt produced is very soluble, and it is then advantageous, by acidifying the reaction mixture with a mineral acid, if necessary after previous cooling and exhaustion with a solvent, like ether, toluene or carbon tetrachloride to isolate the free acid. These has mostly only a low solubility in the reaction mixture, so that when Adding the mineral acid, a large proportion is separated out, which is filtered through, Extract with a solvent or at temperatures where the acid is liquid can be obtained by decanting or siphoning. The reaction product can be acidified with a mineral acid even when hot. The chloraryloxy fatty acid then separates out on cooling. The crude acid can be recrystallized, z. B. made of carbon tetrachloride or toluene, cleaned.

These methods. can e.g. B. be used when chloraryloxy fatty acids can be prepared from chlorine-o-cresols. On the other hand, in some cases, e.g. B. in the case of the 2,4-dichlorophenoxy fatty acids, the i-chloro-2-naph: thoxy fatty acids and of the 2, 4, 6-trichlorophenoxy fatty acids, the sodium salt is only slightly soluble and separates from the reaction mixture on refluxing, so that the crude Salt can then be recovered by filtration. Instead of implementing the chlorinated phenol with monochloroacetic acid can react with other α-halogen fatty acids kick, e.g. B. with α-chloropropionic acid, α-bromopropionic acid and similar derivatives butyric acid and isobutyric acid. In the same way, instead of caustic soda another alkali hydroxide or alkali carbonate or an alkaline earth hydroxide is used turn around.

The following examples in which the parts are given as parts by weight explain the invention. Example i Zoo parts of 4-chloro-2-methylphenol obtained by chlorinating Kresäl, were with 132 parts of monochloroacetic acid and one Solution of 125 parts of caustic soda mixed in 500 parts of water. The mixture became 1 '/ 2 hours heated under reflux and therein with 33 parts of chloroacetic acid and then mixed with a solution of 24 parts of caustic soda in 50 parts of water. The mixture was then refluxed for an additional 1/2 hour. Bet on this 100 parts of water were added and the reaction mixture was allowed to cool. Now the cold one became Liquid with stirring 20% aqueous hydrochloric acid added until the whole thing against Congo Red was pissed off. 286 parts of acid were used for this.

The precipitated sticky, solid mass was filtered off with water washed and dried at 100 °. There were 300 parts of dry, crude 2-methyl-4-chlorophenoxyacetic acid obtained the 215 parts of the pure acid and 29.5 parts of unchanged 4-chloro-2-methylphenol contained.

The pure acid could from the crude product by esterification under Using methyl alcohol and sulfuric acid can be obtained, whereupon the ester washed with aqueous alkali to remove the chloromethylphenol and with mineral acid was hydrolyzed.

When carrying out the same experiment with equivalent amounts of Reactants who were refluxed for three hours were only 258 Parts of the dry, crude acid obtained from 176 parts of pure acid and 6o Parts of 4-chloro-2-methylphenol passed. Example 12 zoo parts 4-chloro-2-methylphenol were with 132 parts of monochloroacetic acid and a solution of 125 parts of caustic soda mixed in 500 parts of water. The mixture was refluxed for 1 1/2 hours and then with 33 parts of chloroacetic acid and subsequently with a solution of 24 Parts of caustic soda are added to parts of water. The mixture then became an additional 1/2 Heated under reflux for hours. The hot liquid was then added with stirring concentrated hydrochloric acid added until the whole thing was sour against Congo red. Therefor zoo parts were used acid. A layer formed almost immediately of liquid 2-methyl-1-chloro-enoxyacetic acid, whereupon the overlying aqueous layer siphoned off and left to stand until cold became. In this way a further amount of crude acid was deposited and removed. The crude acid layer from which the aqueous layer had been siphoned off, was washed at 50 ° with 100 parts of water and dried. A total of 254 Parts of the dry, crude acid obtained from 228 parts of pure acid and 21 Parts of 4-chloro-2-methylphenol passed.

When the same experiment was carried out with equivalent amounts of the reactants by heating under reflux for 3 hours and working up the reaction product in the same way, only 2.fo parts of the dry, crude acid were obtained, which was obtained from 188 parts of pure acid and .f5 parts of unchanged 4-chloro. 2-methylphenol passed. Example 3 150 parts of i-chloro-2-naphthol were refluxed with 79.5 parts of monochloroacetic acid and 70.5 parts of caustic soda, which were dissolved in 280 parts of water. After a few minutes the reaction mixture became semi-solid. A further 300 parts of water were then added and refluxing continued for 2 hours. After heating for 2 hours, a solution of 20 parts of monochloroacetic acid and II parts of sodium hydroxide in 45 parts of water was added and heating continued for an additional hour. The reaction mixture was then filtered, and the remaining solid oil was washed with 300 parts of cold water and then dried at 100 °. 176 parts of sodium i-chloro-2-naphthoxyacetate were obtained in this way, corresponding to a yield of 810/0.

In the same attempt, in which no subsequent addition was made of monochloroacetic acid and sodium hydroxide, the yield was of the sodium salt isolated in the same way only 73.5%.

The free i-chloro-2-naphthlioxyacetic acid was obtained from the sodium salt by grinding with concentrated aqueous hydrochloric acid and recrystallization Obtain toluene. It consisted of diamond-shaped platelets with a melting point from 169 °.

Claims (3)

PATENT CLAIMS: i. Process for the preparation of Chlorarvloxvfettsäuren or their salts by reacting nuclear chlorinated phenols with a substantial excess of α-halogen fatty acid in the presence of excess alkali, characterized in that the acid is added together with the excess alkali during the reaction in parts. 2. The method according to claim i, characterized in that that first stoichiometric amounts of the chlorinated phenol and the halogenated fatty acid be reacted in the presence of a small excess of alkali and then another The proportion of the halogenated fatty acid in the amount of at least a quarter of that previously used Amount is added together with a small excess of alkali. 3. Process according to Claims i and 2, characterized in that the chlorinated phenol used is 4-chloro-2-methylphenol and the α-halogen fatty acid used is monochloroacetic acid. Cited references: Journal of the American Chemical Society 1931, Vo1.53, pp. 304-305 ; Journal for practical chemistry 114, p.297; Liebig's Annalen der Chemie 342, pp. 115 to 118.