NL8900279A - PROCESS FOR THE PREPARATION OF N-PHOSPHONO-METHYL-IMINO-DIACETIC ACID AND ACID CHLORIDE. - Google Patents

Description

NL 35722-Kp / vD '

Process for the preparation of N-phosphono-methyl-imino-diacetic acid and acid chloride.

The invention relates to the simultaneous preparation of N-phosphono-methyl-imino-diacetic acid and lower carboxylic acid chlorides using a new method.

N-phosphono-methyl-imino-diazic acid is an important intermediate in the preparation of glyphosate herbicide with a wide spectrum of activity. In addition, carboxylic acid chlorides are also important and are often used as reagents in organic chemical syntheses. The simultaneous economic preparation of the two products has hitherto not been described in the literature.

The preparation method of N-phosphono-methyl-imino-di-acetic acid is described in British Pat. formaldehyde. According to the reaction, hydrochloric acid is first added to the aqueous solution of imino-diacetic acid sodium salt, and part of the water is distilled off.

Then phosphorus trichloride is added at a temperature of 110-112 ° C. The reaction mixture obtained contains imino diacid acid hydrochloride salt, sodium chloride, water and phosphoric acid. Then an aqueous formaldehyde solution is added to the reaction mixture at a temperature of approx.

108-110 ° C, after which the reaction takes place at that temperature for at least 1 hour. At the end of the reaction, sodium hydroxide is added to the reaction mixture, the reaction mixture is filtered and the filter cake is washed many times with water and finally dried. The yield is about 87.9%. The drawback of this method is that under the influence of water the hydrochloric acid, which is formed from phosphorus trichloride next to the phosphoric acid, cannot be used and that its destruction is associated with high costs and seriously pollutes the environment.

The parallel formed sodium chloride cannot be used either, it contaminates the final product and can only be removed from 6900273 / - 2 - the final product after several washings.

British Pat. No. 2,021,589 first reacts phosphorus trichloride and water at a temperature below 40 ° C for the preparation of N-phosphono-methyl-5-imino-diacetic acid, after which imino-diacetic acid is added to the solution with boiling, then the aqueous formaldehyde and 2/3 of the water are distilled off. After the addition of ethanol, N-phosphono-methyl-imino-diacetic acid precipitates from the solution, after which the precipitated crystals are washed with ethanol and water. The disadvantage of the process is, inter alia, that the majority of the 3 moles of hydrochloric acid formed per mole used for the decomposition of phosphorus trichloride are not used in the process because one third of the hydrochloric acid formed is sufficient for the phosphonomethylation process. The decomposition of the hydrochloric acid adversely affects the economy of the process and causes environmental pollution.

The other known methods are based on similar principles, their common aspect being that the chlorine atoms of phosphorus trichloride are used to form hydrochloric acid or are converted to sodium chloride, removing both the economy and the quality of the product adversely affects.

The object of the present invention is to make full use of the chlorine atoms of the phosphorus trichloride used by preparing N-phosphono-methyl-imino-diacetic acid. Another object is to eliminate the pollution of the environment and the destruction of the harmful by-products, such as hydrochloric acid and sodium chloride, as well as to prevent their formation.

The process according to the invention for the simultaneous preparation of N-phosphono-methyl-imino-diacetic acid and lower carboxylic acid chloride using imino-diacetic acid and phosphorus trichloride is characterized in that phosphorus trichloride is converted with a C 1-4 carboxylic acid into a molar ratio of about 1: 3, after which the formed phosphoric acid and carboxylic acid chloride are isolated and the carboxylic acid chloride is separated. After dilution with water, the phosphoric acid phase, which also contains carboxylic acid and carboxylic acid chloride, is reacted with imino diacetic acid and the aqueous formaldehyde solution at a temperature between 60-120 ° C in the presence of an mineral acid, preferably in the presence of hydrochloric acid, after which the mixture is evaporated to leave a crystalline product. The molar ratio of imino diacetic acid to phosphoric acid and formaldehyde is about 1: 1-1.1: 1.2.

Phosphorus trichloride and carboxylic acid, preferably acetic acid, are reacted at 0-20 ° C. The carboxylic acid and carboxylic acid chloride, in addition, the hydrochloric acid content of the phosphoric acid phase, formed by conversion of phosphorus trichloride and carboxylic acid, can be reduced by distillation. To promote the precipitation of N-phosphono-methyl-imino-diacetic acid obtained at the end of the synthesis, the reaction mixture is evaporated to about 2/3 of its volume.

In order to obtain the advantages of the invention, it is not an important requirement the removal of the individual components from the reaction mixture, which is obtained after conversion of phosphorus trichloride and carboxylic acid, while, moreover, the precipitation of the unreacted components or the starting materials is of no importance. .

The phosphoric acid and the carboxylic acid chloride as well as carboxylic acid can be isolated from the phases by simple sedimentation or by distillation or by the extraction of the phosphoric acid phase.

Carboxylic acid can be converted to the given molar ratio at a temperature between -10 and + 100eC, preferably at 0-20 * C according to the following equation: 30 PC13 + 3 R-COOH-? H3P03 + RCOC1

In addition to cooling and stirring, it is preferable to add phosphorus trichloride to the carboxylic acid, however the process can be carried out by adding the materials in reverse order. After the reaction, the acid chloride and phosphoric acid formed are present in two phases, separated from each other. The upper acid chloride phase is isolated for further use. The lower phosphoric acid phase generally contains 80-98% phosphoric acid, 2-0% carboxylic acid and 89 00279

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- 4 - 1-5% carboxylic acid chloride. The bottom phase obtained from the reaction mixture can be directly reacted with the aqueous formaldehyde solution at the given temperature. In fact, the process is carried out by adding the aqueous solution of formaldehyde to the mixture of phosphoric acid, imino diacetic acid and aqueous hydrochloric acid at the temperature of the boiling point of the mixture. After evaporation, the crystalline end product precipitates and can be separated by filtration.

The advantages of the process can be summarized as follows: - when reacting phosphorus trichloride and carboxylic acid in the correct molar ratio, phosphoric acid suitable for the preparation of N-phosphonomethyl-imino-diacetic acid and a separate carboxylic acid chloride to be used formed; - the chlorine atoms of phosphorus trichloride can be fully utilized, while the decomposition of the detrimental hydrochloric acid excess is not necessary.

20 - Part of the environmental investments can be saved, while a neutralized by-product (NaCl) does not cause pollution of the environment.

The main reaction mixture does not contain sodium chloride, so that the impurity of the final product caused by sodium chloride inclusions can be eliminated.

- The process can be carried out in the usual chemical equipment.

The method according to the invention is further elucidated on the basis of the following non-limitative Examples:

EXAMPLE I

180 g (3 moles) of acetic acid were weighed into a coolable and heatable four-necked flask equipped with a stirrer, thermometer and reflux condenser. From a filling funnel 35, 137.3 g (1.0 mole) of phosphorus trichloride was added at a temperature below 40 ° C. The reaction mixture was then heated to 40-50 ° C and stirred at that temperature for 30 min.

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The resulting mixture was then stored, with the separated phases meanwhile being processed. The top phase containing acetyl chloride has been isolated and is available for technical purposes. The lower phase 5 of 96 g and containing phosphoric acid and additionally 6 wt% hydrochloric acid, 2 wt% acetyl chloride and 10 wt% acetic acid was mixed with 30 ml water and then transferred to a filling funnel.

Into the former flask, 119.7 g (0.9 mol) of TO imino-diacetic acid, 130 ml of water and 48 g of a 37 wt% hydrochloric acid were introduced, followed by the addition of the bottom phase obtained in the previous step and containing phosphoric acid on the hopper with stirring. The mixture thus obtained was heated to boiling point, after which 97 g (1.1 mol) of a 34% aqueous formaldehyde was added. The reaction mixture was heated to reflux for an additional hour, after which 2/3 of its volume was distilled off. Then, the mixture was cooled to 10 ° C, the resulting crystals were filtered off, washed with cold water and dried, yielding 173 g of N-phosphono-methyl-imino-diacetic acid with a boiling point of 208-209 ° C.

The yield was 84.6% based on imino diacetic acid.

EXAMPLE II

The procedure of Example I was followed with the proviso that the phosphorus trichloride, the amount of hydrochloric acid, acetic acid and acetyl chloride present in the lower phase, which was obtained by conversion of phosphorus trichloride and acetic acid, was distilled off. The amount of the 37% hydrochloric acid added was found to increase to 74.7 g as a result of the reaction. The phosphoric acid phase thus obtained, containing 2% hydrochloric acid, 1% acetyl chloride and 4% acetic acid, was further reacted according to Example I.

This gave 173.1 g of N-phosphono-methyl-imino-diacetic acid-35 with a boiling point of 209 ° C. This is 84.7% of the theoretical yield.

EXAMPLE III

The procedure described in Example I was followed 83 00279.

-. It is understood that the acetic acid and the acetyl chloride content of the phosphoric acid phase obtained during the reaction of phosphorus trichloride and acetic acid were reduced by respectively. repeated addition of phosphorus trichloride and the subsequent precipitation. The phosphoric acid phase thus obtained, containing 7% acetic acid, 1.5% acetyl chloride and 4% hydrochloric acid, was added to the mixture of 152.5 g (0.9 mol) imino-diacetic acid hydrochloride with 150 ml water. The resulting mixture was heated to boiling, then 97 g (1.1 mol) of a 34% aqueous formaldehyde was added over 1 hour. Then the mixture was refluxed for an additional 2 hours, after which the mixture was evaporated to 2/3 of its volume and N-phosphono-methyl-imino-diacetic acid was crystallized.

176 g of the product were obtained with a boiling point of 209-210 ° C, which corresponded to 86.2% of the theoretical yield.

8900279.

Claims (3)

Process for the simultaneous preparation of N-phosphono-methyl-imino-diacetic acid and lower acid chloride using imino-diacetic acid and phosphorus trichloride, characterized in that phosphorus trichloride is reacted with a C 4 carboxylic acid in a molar ratio of approx. 1: 3 at a temperature between 0-20 ° C, whereby the formed phosphoric acid phase is separated from the carboxylic acid chloride and the carboxylic acid chloride is isolated, after which, after dilution with water, the phosphoric acid phase, which also contains carboxylic acid and carboxylic acid chloride, is reacted with imino diacetic acid and the aqueous solution of formaldehyde, while the molar ratio of imino acetic acid to phosphoric acid and formaldehyde is about 1: 1-1.1: 1-1.2, in the presence of an added strong mineral acid, preferably hydrochloric acid at a temperature between 60-120 ° C, after which the mixture is evaporated until crystals are formed. 2. Process according to claim 1, characterized in that acetic acid is used as the carboxylic acid. 3. Process according to claim 1, characterized in that the amount of carboxylic acid and carboxylic acid chloride, respectively. hydrochloric acid, present in the phosphoric acid phase, which is obtained during the conversion of phosphorus trichloride and carboxylic acid, is reduced by distillation or by treatment with phosphorus trichloride before the reaction with formaldehyde. 89 00 279.