CS217660B1 - Process for removing chlorocresols from ammonium or amine salts of 2-methyl-4-chlorophenoxyacetic acid - Google Patents

Abstract

The invention addresses the reduction of chlorocresols in ammonium or amine salts of 2-methyl-4-chlorophenoxyacetic acid. Chlorocresols are removed from ammonium or amine salts of 2-methyl-4-chlorophenoxyacetic acid by steam. Chlorocresols contained in the distillate are converted by the action of alkali hydroxide into alkaline chlorocresols, which, by condensation with alkali metal chloroacetate, form chlorine-substituted phenoxyacetic acids. (The invention can be used in the reduction of phenol derivatives from herbicides of 2-methyl-4-chlorophenoxyacetic acid.

Description

The invention relates to a process for the removal of chlorocresols from the ammonium or amine salts of 2-methyl-4-chlorophenoxyacetic acid (MCPA).

The ammonium and amine salts are prepared according to the following reactions:

OH • t NaOH - *

/ 1 /

2C1CH ₂ OOOH + Na ₂ CO ₃

2ClCH ₂ CO ₂ Na + CO ₂ + HgO / 2 / • OCH ₂ COONa

ONa

CH ³ + CICHgCOONa,

OH ³ + NaCl (3)

(4) (5) (6) wherein R 1 is hydrogen or alkyl of 1 to 10 carbon atoms and R 2 is alkyl of 1 to 10 carbon atoms, or aryl of 6 to 10 carbon atoms.

The introduction of chlorine into an aqueous solution of sodium, potassium, or sodium potassium salts of 2-methylphenoxyacetic acid (MPA) at a temperature of 0-120 ° C and a pH value of 3-4 protects the MS. pat. 91160. Continuous chlorination is given by MS. pat. 99892. The MPA alkali salt solution and the alkali metal cresolate solution are condensed in a reactor cascade to form an alkaline salt having a pH of 6-7 which is continuously broken off on the column by direct steam and chlorinated to form MCPA which is continuously neutralized to alkaline sol 'as reported by MS. pat. 107807, the chlorination of MPA in paraffin indicates Swedish. pat. No. 154441, the chlorination in aqueous sodium bicarbonate solution is protected by U.S. Pat. 855504. A second method of producing MCPA is to first chlorinate ortho-cresol with chlorine, sulfuryl chloride, or alkaline hypochlorite. Chlorination with sulfuryl chloride in chlorinated hydrocarbons, preferably trichlorethylene, is indicated by crayfish. pat. 260910, chlorination in the presence of organic nitrogen compounds protects the crayfish. pat. 262265. The preparation of 4-chlorotortresol in the presence of anhydrous aluminum, ferric, stannic, zinc chloride from ortho-cresol is shown in U.S. Pat. V. Brit. 926,014th

Melt after chlorination according to MS. pat. 99892 contains about 2.5-5% by weight of chlorinated cresols, 80-88% by weight of phenoxy acids containing 5-15% by weight of MPA, 55-70% by weight of MCPA, 5-10% by weight of 2-methyl-4,6-dichlorophenoxyacetic acid acid, 7-15% by weight of 2-methyl-6-chlorophenoxyacetic acid and some undefined organic substances. After neutralization of the melt with an aqueous ammonia solution, the solution contains 50-60% by weight of ammonium salts of phenoxy acids, the content of ammonium salts of chlorocresols 1.5-3.5% by weight of free ammonia 0.3-1% by weight and a pH of 10-12. After neutralization of the melt with an aqueous dimethylamine solution, the solution contains 45-55% by weight dimethylamine salts of phenoxy acids, 1,3-

3.5% by weight of dimethylamine salts of chlorocresols, free dimethylamine 0.1 - 1% by weight;

The above drawbacks are overcome by the method of removing chlorocresols from the ammonium or amine salts of 2-methyl-4-chlorophenoxyacetic acid, which comprises treating the ammonium or amine salts of MCPA with water vapor. The chlorocresols contained in the distillate are converted into alkali chlorocresolates by treatment with alkali metal hydroxide, which, by condensation with alkali metal chlorate, forms chloro-substituted 2-methylphenoxyacetic acids. The MCPA content of the chloro-substituted MCPA derivatives is 30 to 80% by weight.

By reducing the chlorocresols content of the ammonium and amine salts of phenoxyacetic acids, the quality of these products is improved. Phenoxyacetic acids having herbicidal activity can be prepared from chlorocresols which do not have a herbicidal action.

Example 1

A 500 ml three-necked flask equipped with a thermometer, a frit for steam injection and a condenser was charged with 250 g of a 52.3% ammonium salt of phenoxyacetic acid, of which 63.7% was the ammonium salt of 2-methyl-4-chlorophenoxyacetic acid. The chlorocresols content was 3.22%, the free ammonia concentration was 0.42%. Ammonium salts of chlorocresols were distilled off with steam for 1 hour. After steam distillation, the concentration of ammonium salts of phenoxyacetic acids was 51.8% and the chlorocresols content was 1.94%, the free ammonia content was 0%. Ammonia was ejected from the distillate after alkalization of the sodium hydroxide to pH 10 by heating to 60 ° C. The resulting alkaline chlorocresolate was condensed with sodium chloroacetate to be converted to phenoxyacetic acids containing 64.3% by weight of MCPA.

Example 2

A 500 ml three-necked flask equipped with a condenser, thermometer, and water vapor frit was charged with 250 g of 43.2% dimethylamine salt of phenoxyacetic acids, of which the dimethylamine salt content of 2-methyl-4-chlorophenoxyacetic acid was 71.3%. The chlorocresols content was 2.36%, the free dimethylamine content 0.62%. After the chlorocresols were distilled off for 1.5 hours, the concentration of the dimethylamine salt of phenoxyacetic acids was

41.8%, chlorocresols content 0.62%. In the distillate, the pH was adjusted to 10 by addition of sodium hydroxide. Dimethylamine was expelled by heating to 70 ° C. Alkaline chlorocresolate by condensation with sodium chloroacetate was converted to phenoxyacetic acids containing 57.6% MCPA.

Reducing the content of chlorocresols in the ammonium and amine salts of MCPA will improve their quality, since the content of chlorocresols is one of the quality indicators. It is best to keep the water vapor continuous on the column.

Claims (1)

3 Melt after chlorination according to MS. pat. 99892 contains about 2.5-5% by weight of chlorinated cresols, 80-88% by weight of phenoxy acids containing 5-15% by weight of MPA, 55-70% by weight of MCPA, 5-10% by weight of 2- methyl 4,6-dichlorophenoxyacetic acid, 7-15% by weight of 2-methyl-6-chlorophenoxyacetic acid and some undefined organic matter. After neutralization of the melt with an aqueous solution of ammonia, the solution contains 50-60% by weight of the ammonium salts of phenoxyacids, the content of ammonium salts of chlorocresols is 1.5-3.5% by weight of free ammonia 0.3-1% by weight and the pH of 10-12. . After neutralization of the melt with an aqueous solution of dimethylamine, the solution contains 45-55% by weight of dimethylamine salts of phenoxyacids, 1.3-3.5% by weight of dimethylamine salt chlorocresols, free dimethylamine 0.1-1% by weight. The aforementioned drawbacks are eliminated by the process of removing chlorocresol from ammonium or amine salts of 2-methyl-4-chlorophenoxyacetic acid, which results in the formation of water vapor on the ammonium or ammonium salts of MCPA. The chlorocresoles contained in the desilate are converted into alkali chlorocresollates by alkali metal hydroxide, which are chloro-substituted 2-methylphenoxyacetic acid with alkali metal chloroacetate. The MCPA content of the chloro-substituted MCPA is 30 to 80% by weight. By reducing the content of chlorocresols in the ammonium and amine salts of phenoxyacetic acids, the quality of these products is increased. Phenoxyacetic acids having a herbicidal effect can be prepared from the chlorocresols which do not have a herbicidal action. EXAMPLE 1 250 g of 52.3% solution of ammonium salts of phenoxyacetic acids were added to a 500 ml three-necked flask with a water meter, a water vapor frit and a condenser, of which 63.7% was an ammonium salt of 2-methyl-4-chlorophenoxyacetic acid. The chlorocreole content was 3.22%, the free ammonia concentration was 0.42%. Chlorocresols in the form of ammonium salts were distilled off with steam for 1 hour. At the end of the distillation, the concentration of ammonium salts of oxy-acetic acids was 51.8% and the content of chlorocreole was 1.94%, the free ammonia content of 0% of the distillate, after alkalizing the hydroxide to pH 10, heated the temperature of 60 ° C with ammonia. The resulting alkaline chlorocresol was converted to phenoxyacetic acids containing 64.3% by weight of MCPA by condensation with sodium chloroacetate. EXAMPLE 2 250 g of a 43.2% dimethyl amine salt of phenoxyacetic acids were obtained in a 500 ml three-necked flask equipped with a condenser, a thermometer, a frit for steam injection, of which the content of dimethylamine salt of 2-methyl-4-chlorophenoxyacetic acid was 71.3. %. The chlorocresol content was 2.36%, the free dimethyl amine content was 0.62%. After 1.5 hours distillation of the chlorocresols, the concentration of the dimethylamine salt of phenoxyacetic acids was 41.8%, the content of chlorocresols was 0.62%. The pH was adjusted to 10 by addition of sodium hydroxide in the distillation. Dimethylamine was heated to 70 ° C. Alkaline chlorocresolate condensation with sodium chloroacetate was converted to phenoxyacetic acids containing 57.6% MCPA. By reducing the chlorocresols content of the ammonium and amine salts of MCPA, their quality is increased because the chlorocresols content is one of the qualitative indicators. The best sets do not constantly convert on the column vodnouparou. DISCLOSURE OF THE INVENTION A method for the removal of ammonium or amine salts of 2-methyl-4-chlorophenoxyacetic acid, wherein the ammonium or amine salts of 2-methyl-4-chlorophenoxyacetic acid are acid-steamed, the chlorocresols contained in the desilicate by treatment with alkali hydroxide. The latter is converted into the alkali chlorocresollates, which are produced by the alkali chloroacetic acid to form chloro-substituted 2-methylphenoxyacetic acid with a 2-methyl-4-chloro-phenoxyacetic acid content of 30 to 80% by weight.